WO2021007351A1

WO2021007351A1 - Pneumatic needle control

Info

Publication number: WO2021007351A1
Application number: PCT/US2020/041255
Authority: WO
Inventors: Ethan GLASSMAN; Benjamin KRASNOW; Michael Chen; Stephen O'driscoll; Uei-Ming Jow; Todd Whitehurst
Original assignee: Verily Life Sciences Llc
Priority date: 2019-07-10
Filing date: 2020-07-08
Publication date: 2021-01-14

Abstract

Injection device needle positioning is controlled with a needle movable in response to piston movement. A chamber with first and second ends contains the piston for travel along a travel path including first and second travel path positions. An extender proximate the first chamber end includes an extension propellant activatable to produce a first pressure at the first chamber end to move the piston from the first travel path position toward the second travel path position to cause the needle to extend. A retractor positioned proximate the second end of the chamber generates retracting movement of the piston from the second travel path position toward the first travel path position to cause the needle to retract. A vent defined through a chamber wall between the first travel position and the first chamber end dissipates at least a portion of the first pressure to facilitate the retraction.

Description

PNEUMATIC NEEDLE CONTROL

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from and the benefit of U.S.

Provisional Application No. 62/872,337, entitled“Pneumatic Needle Control,” filed July 10, 2019 (Attorney Docket No. 101146-1132589-374PV1), the full disclosure of which is incorporated herein by reference for all purposes.

TECHNICAL FIELD

[0002] The present application generally relates to drug injection devices, and more specifically relates to systems and methods for wearable emergency drug injection devices.

BACKGROUND

[0003] People with certain medical conditions may require doses of medication in response to certain physiological conditions. For example, a diabetic may monitor her blood sugar and, if it gets too high, inject insulin to help lower the blood sugar levels. Conversely, she may eat some food if her blood sugar gets too low. Another example is a person with an allergy to peanuts or insect stings that experiences anaphylaxis as a result of contact with the allergen. To respond to the anaphylaxis, the person may inject herself with epinephrine, such as with an off-the- shelf epinephrine injector, e.g., an EpiPen®.

SUMMARY

[0004] Various examples are described for systems and methods for wearable emergency drug injection devices. For example, one disclosed example method of controlling injection device needle positioning includes extending a needle out of a body of an injection device by movement of a piston bearing the needle from a first travel path position at a first end of a chamber to a second travel path position toward a second end of the chamber, the movement of the piston in response to activation of an extension propellant that generates a first pressure increase between the first end of the chamber and a first side of the piston; and retracting the needle into the body of the injection device by additional movement of the piston bearing the needle from the second travel path position toward the first end of the chamber and in response to activation of a retraction propellant that generates a second pressure increase between the second end of the chamber and a second side of the piston opposite the first side of the piston.

[0005] The method may further include venting at least a portion of the first pressure increase through a vent positioned between the first end of the chamber and the first travel path position or positioned through an end wall at the first end of the chamber.

[0006] One disclosed example system for controlling injection device needle positioning includes a piston; a needle movable in response to movement of the piston; a chamber bounded by chamber walls, having a first end and a second end, and sized to receive the piston therein for travel along a travel path including a first travel path position and a second travel path position; an extender positioned proximate the first end of the chamber and comprising an extension propellant activatable to produce a first pressure at the first end of the chamber to move the piston from the first travel path position toward the second travel path position to cause the needle to extend; a retractor positioned proximate the second end of the chamber and operable to generate retracting movement of the piston from the second travel path position toward the first travel path position to cause the needle to retract; and a vent to dissipate at least a portion of the first pressure and defined through a chamber wall in a portion of the chamber defined between the first travel path position and the first end of the chamber.

[0007] One disclosed example auto-injector device includes a first chamber having a first origin end and a first terminus end; a first piston positioned within the first chamber, the first piston having a primary side and a secondary side, the first piston bearing a hollow needle on the secondary side such that the needle is movable by the first piston to extend through the first terminus end of the first chamber, and the first piston defining a laterally-facing conduit defining a fluid path to the hollow needle; a second chamber having a second origin end and a second terminus end, the second chamber containing medication, and the second chamber defining an outlet at the second terminus end; a second piston positioned within the second chamber and proximate the second origin end, the second piston moveable to force the medication out of the second chamber through the outlet of the second chamber; a third chamber having a third origin end and a third terminus end and in fluid communication through the third terminus end with the secondary side of the first piston; a first cap positioned at the first origin end of the first chamber and having a first vent and a first heat source; a first propellant positioned in the first chamber and between the first heat source and the first piston; a second cap positioned at the second origin end of the second chamber and having a second heat source; a second propellant positioned in the second chamber and between the second heat source and the second piston; a third cap positioned at the third origin end of the third chamber and having a third heat source; a third propellant positioned in the third chamber and between the third heat source and the third terminus end; a processor configured to: at a first time, trigger the first heat source for activating the first propellant to exert fluid pressure on the first piston to cause the needle to extend out the first terminus end of the first chamber and cause the laterally-facing conduit of the first piston to align with the outlet of the second chamber; at a second time after the first time, trigger the second heat source for activating the second propellant to exert fluid pressure on the second piston to cause the second piston to send the medication through a fluid passage defined by the aligned outlet, laterally-facing conduit, and needle; and at a third time after venting of pressure build-up within the first chamber between the first cap and the primary side of the first piston, trigger the third heat source for activating the third propellant to exert fluid pressure on the secondary side of the first piston to overcome pressure dissipated on the primary side of the first piston through the first vent and urge the first piston toward the first origin end of the first chamber to retract the needle.

[0008] These illustrative examples are mentioned not to limit or define the scope of this disclosure, but rather to provide examples to aid understanding thereof. Illustrative examples are discussed in the Detailed Description, which provides further description. Advantages offered by various examples may be further understood by examining this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more certain examples and, together with the description of the example, serve to explain the principles and implementations of the certain examples.

[0010] Figures 1A-1C show an example wearable emergency drug injection device according to this disclosure; [0011] Figure 2 shows an example system for wearable emergency drug injection devices according to this disclosure;

[0012] Figure 3 shows an example needle guide for wearable emergency drug injection devices according to this disclosure;

[0013] Figure 4 is a graph showing pressure conditions for a chamber for wearable emergency drug injection devices according to this disclosure;

[0014] Figures 5 shows an end view of an example injection portion for wearable emergency drug injection devices according to this disclosure;

[0015] Figures 6A-6D show an example injection portion for wearable emergency drug injection devices according to this disclosure;

[0016] Figures 7 shows an example wearable emergency drug injection device according to this disclosure;

[0017] Figure 8 shows an example method for using a wearable emergency drug injection device according to this disclosure;

[0018] Figures 9A-9B show an example wearable emergency drug injection device according to this disclosure; and

[0019] Figure 10 shows an example method for using a wearable emergency drug injection device according to this disclosure.

DETAILED DESCRIPTION

[0020] Examples are described herein in the context of systems and methods for wearable emergency drug injection devices. Those of ordinary skill in the art will realize that the following description is illustrative only and is not intended to be in any way limiting. Reference will now be made in detail to implementations of examples as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following description to refer to the same or like items.

[0021] In the interest of clarity, not all of the routine features of the examples described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer’s specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. [0022] A person with a medical condition, such as diabetes or a severe allergy to a substance, may use a wearable emergency drug injection device according to this disclosure. In this example, the person (also the“wearer”) obtains the device, which is approximately an inch wide, one and a half inches long, and half an inch tall (e.g., approximately 2.54 cm by 3.81 cm by 1.27 cm). The example device has two halves that clip together to form the completed device.

[0023] One half, the disposable half, has components to store and deliver a dose of an injectable medication. Specifically, the disposable half has three chambers. The first chamber and the second chamber each has its own piston that initially is at a starting end of the respective chamber. The first chamber’s piston is attached to a hollow needle, which will be extended out of the device and into the wearer to enable injection of the substances into the wearer. The injectable medication is contained in the second chamber and can be forced to flow out of the second chamber by movement of the second chamber’s piston. Behind each of the pistons is a small charge that, when activated, generates pressure behind the piston to force the piston to the opposite end (finishing end) of the chamber, for example, so the first chamber’s piston will push the needle outward and so the second chamber’s piston will drive the medication through the extended needle. The third chamber is joined by a passage to the finishing end of the first chamber and includes a further small charge, which can be activated to generate pressure in front of the first chamber’s piston to push it backwards toward the starting end of the chamber and retract the needle back inward into the first chamber so that the needle does not remain exposed after delivery of the medication has been completed.

[0024] The second half of the device, the reusable half in this example, includes circuitry to receive a command to inject the injectable substance and to activate the three small charges in response to the command. For example, the wearer could press a button on the reusable half to trigger the circuitry to activate the charges. Alternatively, the circuitry could receive the command wirelessly from another device, such as the wearer's smartphone, continuous glucose monitor (“CGM”), insulin pump, etc.

[0025] In this example, the circuitry is configured to activate the three charges in sequence. The first charge forces the first piston towards the finishing end of the chamber, which forces the needle to extend out of the device and bend towards and into the wearer's skin. The needle also has a port into it, and the movement of the needle aligns the needle’s inlet port with an outlet of the medication-containing second chamber.

[0026] After the first charge has activated, the second charge is activated, which forces the piston in the second chamber towards the finishing end of the chamber. The second piston's movement forces the liquid medication out of the second chamber, through the inlet port in the needle, into the hollow needle, and ultimately into the patient. Thus, a dose of medication is delivered to the patient in response to, for example, a CGM detecting a low glucose level and transmitting a signal to the device.

[0027] After the second charge has activated, the third charge is activated, which forces the needle-bearing piston in the first chamber back towards the starting position within the original starting end of the chamber. Thus, the needle is retracted following completion of the medication delivery and is stored safely back within the body of the device.

[0028] In this example, the device also includes a venting arrangement that allows pressure changes that facilitate proper functioning of the needle extension and retraction. A first vent is included in an end wall at the starting end of first chamber, and a second vent is included in an end wall at the starting end of the third chamber. The vents are specially sized so that they are small enough to avoid venting too much when the charge within the same chamber is activated but large enough to allow venting that will facilitate other events triggered when a charge within a different chamber is activated.

[0029] For example, for the needle extension process, when the first charge is activated to extend the needle, the small size of the nearby first vent prevents too much of the resulting pressure from being vented and allows the bulk of the resulting pressure to be expended in driving the first chamber’s piston from the starting end to the finishing end to extend the needle. At the same time, the second vent in the third chamber is big enough to provide an outlet so that air driven in front of the first chamber’s piston can flow through the passage into and through the third chamber and exit through the second vent so that pressure does not build up in the third chamber in a way that would resist the needle-extending movement of the first chamber’s piston.

[0030] In contrast, for the needle retraction process, in between the activation of the first charge to extend the needle and activation of the third charge to retract the needle (e.g., while the medication is being dispensed in response to the intervening second charge), the first vent is large enough that it is venting and allowing pressure to dissipate behind the first chamber’s piston so there will be less resistance to pushing the first chamber’s piston backward when it comes time to retract the needle. When that time comes and the third charge is activated in the third chamber to trigger retraction of the needle, the small size of the nearby second vent in the third chamber minimizes an amount of that resulting additional pressure that is vented instead of being expended in passing through the passage to the first chamber for driving the first chamber’s piston back toward the starting position for retracting the needle.

While the first chamber’s piston is being moved back toward the starting position, the first vent in the first chamber may also allow venting behind the first chamber’s piston to reduce resistance to the needle-retracting movement of the first chamber’s piston.

[0031] This illustrative example is given to introduce the reader to the general subject matter discussed herein and the disclosure is not limited to this example. The following sections describe various additional non-limiting examples and examples of systems and methods for wearable emergency drug injection devices.

[0032] Referring now to Figure 1 A, Figure 1 A shows an example wearable emergency drug injection device 100. The example device 100 in Figure 1 A generally includes respective components of an extender 105, a dispenser 107, and a retractor

109. The extender 105 can include appropriate subcomponents to facilitate extending a needle 152 out of the device 100, the dispenser 107 can include appropriate subcomponents to facilitate dispensing medication through the needle (e.g., while extended), and the retractor 109 can include appropriate subcomponents to facilitate retracting the needle 152 back into the device 100 (e.g., after dispensing of the medication is completed). In some examples, certain subcomponents may be subcomponents of more than one of the extender 105, dispenser 107, and retractor 109 (e.g., all may use a shared set of electronic components). Particular examples of subcomponents of each of the extender 105, dispenser 107, and retractor 109 are shown in Figure 1 A and will be appreciated from the discussion herein, although other options are also possible, including various alternatives that will be described below within the context of discussion of respective subcomponents.

[0033] As can be seen in Figure 1 A, the example device 100 has two portions

110, 120 that are connected, but are separable from each other. The first portion 110 has electronic components within it, which are described in more detail below, and an antenna 118 to receive wireless signals. The first portion 110 in this example is separable from the second portion 120 to allow for re-use of the electronics, while the second portion can be discarded after it has been used.

[0034] The second portion 120 has three chambers (at least some of which can be used to store injectable material(s)), as well as a hollow needle 152 and a needle cap 150 that can be used to drive the needle 152 through the needle guide 154 and into a person’s skin. In this example, because the needle 152 is hollow, injectable material(s) can be forced out of one or more of the chambers, through the needle, and into the wearer. In this example, the needle 152 is only coupled to the needle cap 150 and does not extend beyond the needle cap 150 to directly couple with the first piston 132. However, in some examples, the needle 152 extends through or beyond the needle cap 150 and couples to the first piston 132 such that the first piston 132 directly drives the needle 152.

[0035] The example device shown in Figure 1 A is designed to be worn flush against a wearer’s body, such as on an upper arm or torso. The needle 152, as shown in Figure 1 A, is oriented to extend parallel to the wearer’s skin; however, the needle guide 154 defines a curved path that forces the needle 152 to bend towards the wearer’s skin at an angle departing from its initial orientation by approximately 30 degrees in this example. Thus, the needle 152, in this example, is formed of a flexible materials, such as a nickel -titanium alloy ( e.g ., Nitinol), to allow the needle 152 to bend at angles of up to 30 degrees (or more) without breaking or obstructing the fluid path through the interior of the needle 152. In addition, the needle 152 in this example is a 22-gauge needle. Such a needle size may provide a diameter suitable for injecting fluid into the wearer while having a diameter that causes a tolerable amount of discomfort to the wearer; however, other suitable needle diameters may be employed.

[0036] With respect to description of length, width, and height, the height of the device 100 shown in Figure 1 A refers to how far the device extends above the wearer’s skin when worn as described above. The length and width, by contrast, refer to the dimensions of the perimeter of the device 100 shown in Figure 1 A.

Nevertheless, other form factors and/or orientations of the device 100 or respective components may be suitable, including, but not limited to, options in which the needle 152 is utilized without a bending process and/or in which the device 100 is provided in an elongate body or other form factor suitable for handheld deployment relative to a recipient of the medication. [0037] As discussed above, the second portion 120 defines three chambers

122, 124, 126. Within each chamber 122, 124, 126, is depicted a respective piston 132, 134, 136, which is each initially positioned at one end (e.g., a starting end or origin end) of the respective chamber opposite an opening. (It is to be noted that positioning“at” one end of the chamber need not necessarily mean abutting that end, but may encompass any suitable position of being located more near that end than another end.) Thus, when the pistons 132, 134, 136 move along travel paths from starting positions at one end of the chamber toward ending positions at the opposite end of the chamber, contents of the corresponding chamber 122, 124, 126 are expelled through their respective opening, for example, to impart pressure and/or deliver the contents elsewhere.

[0038] The pistons 132, 134, 136 are sized to have approximately the same cross-sectional area as the corresponding chamber 122, 124, 126 to prevent the contents of the chamber 122, 124, 126 from sliding around the piston or gas pressure generated behind the piston from being dissipated by escaping around the piston 132, 134, 136. In addition, in some examples, one or more of the pistons 132, 134, 136 may have one or more ring seals attached around the perimeter of the piston 132, 134, 136 to prevent such leakage of material or gasses past the piston 132, 134, 136.

[0039] A propellant 142, 144, 146 is disposed behind each piston 132, 134,

136. When one of the propellants 142, 144, 146 is activated, it generates pressure within the portion of the chamber behind the piston 132, 134, 136 thereby forcing the piston 132, 134, 136 towards the opposite end (e.g., a finishing end or terminus end) of the chamber.

[0040] In this example, each propellant 142, 144, 146 comprises a

nitrocellulose material, and the first propellant 142 and the third propellant 146 each has a faster-burning nitrocellulose material than the second propellant 144. For example, the first propellant 142 and the third propellant 146 in this example each is a nitrocellulose in a cotton-based format, while the second propellant 144 in this example is a nitrocellulose in a paper-based format. Selection of an appropriate propellant may be made based on the contents of the chamber.

[0041] For example, the first chamber 122 may have no injectable material in it, or may have an amount of an injectable powder or liquid, and thus may provide a mechanism for forcing the needle cap 150 and needle 152 downwards, thereby injecting the needle 152 into the wearer’s skin. In such an example, a faster-burning propellant may be used as concerns about over-pressurizing the first chamber 122 may be reduced. In contrast, in this example, the second chamber 124 has an injectable fluid. Thus, a slower-burning or slower-acting propellant may be desired to allow time for the fluid to be expelled from the second chamber 124 without over pressurizing the chamber walls. In comparison, the third chamber 126 may have no injectable material in it and thus may provide a mechanism for forcing the needle cap 150 and needle 152 upwards, thereby retracting the needle 152 out of the wearer’s skin and into a safely stored state within the device that may eliminate concerns about the needle 152 remaining exposed after use. In such an example, a faster-burning propellant may again be used as concerns about over-pressurizing the chamber may be reduced. In addition, selection of propellants may be made based on a desired firing sequence, a time to deliver a full dose of material to the wearer, or a time between insertion and retraction of the needle 152.

[0042] In some examples, a quantity of propellant for a chamber may be made up of multiple discrete propellant elements, each of which may be individually activatable. Thus, to activate the propellant, each individual propellant element may be activated separately or in combination. In examples where the individual propellant element is activated separately, a firing sequence may be employed to activate the propellant elements to create a desired pressure curve over time. For example, the propellant elements may be activated at regular intervals, e.g ., one every half-second, or several may be activated initially to create a high pressure, e.g. , to drive a needle into the wearer’s skin, followed by successive activation of the remaining propellant elements to slowly and steadily inject a substance into the wearer and eventually trigger needle retraction when the injection is completed.

[0043] To enable the injectable material to move from the chamber(s) into the wearer, as discussed above, the needle 152 is hollow. In addition, a first fluid path 125 is defined between the first chamber 122 and the second chamber 124 to allow injectable material to move from the second chamber 124 through the first fluid path 125 over and/or through the needle cap 150 and into the needle 152. And while it is referred to as a“fluid” path 125, it can allow solid (e.g, powders) or gaseous materials to flow as well. In addition, the first piston 132 can also define a laterally- facing conduit or other void such that, after the first piston 132 has been driven to the opposite end of the first chamber 122, the void is exposed to the fluid path as well as the hollow portion of the needle. Thus, the combination of fluid path 125, the void within the first piston 132, and the hollow needle 152 may provide a path for an injectable material to be expelled from the chamber(s) 122, 124 and into the wearer.

[0044] In addition, in this example, a second fluid path 127 is defined between the first chamber 122 and the third chamber 126 to enable retraction of the needle 152. Namely fluid pressure from the third chamber 126 can be provided through the second fluid path 127 to act on an underside of the needle cap 150 or related structure to push it backward and pneumatically retract the needle 152. In other examples, other needle retraction mechanisms may be employed, such as one or more springs that may provide a spring force that is overcome by the initial pressure generated by the first propellant 142 but that may nevertheless be engaged with the needle cap 150 such that dissipation of the pressure (e.g., via venting) may allow the springs to ultimately overcome the pressure and retract the needle.

[0045] The example device shown in Figure 1 A also includes vents formed through chamber walls. Specifically, the first vent 162 is shown in the first chamber 122 and the second vent 166 is shown in the third chamber 126. Each vent 162, 166 is schematically shown positioned at the starting end of its chamber 122, 126, for example, adjacent the propellant 142, 146 in the chamber 122, 126. The vent 162, 166 may be defined through an end wall or cap that defines an end of the chamber 122, 126, positioned at some other position between the end wall and the starting position of the piston 132, 136, or otherwise positioned to allow venting through the vent 162, 166 during travel of the piston 132, 136. Each vent 162, 166 can be an unobstructed opening that is permanently open to allow passive venting. The respective sizes of the vents 162, 166 may allow pressure build-up and pressure release at alternative times to facilitate actions triggered by different propellants 142, 146, as described further herein.

[0046] While the second portion 120 includes the injectable material(s) and the mechanisms for inserting the needle 152 into the wearer and for storing and expelling the injectable material(s), the first portion 110 includes components to receive a command (or commands) to activate the propellant and inject the injectable material(s). In this example, the first portion 110 includes electronics for activating the propellant, including a firing circuit 112 and a battery 114 or other electrical power source or connection, as well as a wireless receiver 116, and an antenna 118. In some examples the electronics for activating the propellant may also include one or both of the wireless receiver 116 and antenna 118, though other components may be used instead, such as a button. To activate the propellants 142, 144, 146 and extend the needle 152, inject the injectable material into the wearer, and/or retract the needle 152, in this example, a command is received via the antenna 118 and the receiver 116 from a remote device, such as the wearer’s smartphone or a biosensor ( e.g ., a CGM), and is provided to the firing circuit 112. In response to receiving the command, the firing circuit 112 activates the propellants 142, 144, 146 using power supplied by the battery 114.

[0047] In this example, the propellants 142, 144, 146 are activated by an electrical discharge. To supply the electrical discharge, the firing circuit 112, prior to receiving the command in this example, charges three capacitors using the battery 114. Upon receiving the command from the receiver 116, the firing circuit 112 couples the capacitors, in sequence, to electrical leads in contact with the respective propellant 142, 144, 146 thereby allowing them to discharge and activate the corresponding propellant 142, 144, 146.

[0048] As described above, the firing circuit 112 in this example includes capacitors selectably connected to a corresponding propellant charge. By closing a corresponding switch, e.g., a transistor, the capacitor’s charge is delivered to the propellant 142, 144, 146 activating it. For example, the charge may be applied to a resistor in contact with the propellant. The charge may cause the resistor to generate heat, which ignites the propellant. In addition to or in lieu of a resistor, a different heat source (e.g., a light source), spark source (e.g., two electrodes arranged to form an air gap), or other activator may be utilized to activate the propellant.

[0049] In addition to the firing circuit 112, other electronic components may be provided within the first portion 110 as well, such as battery charging circuitry, which may include a wired connection or a wireless power antenna and rectifier, power and filtering circuitry, and a microcontroller, e.g, an ASIC defined on a field- programmable gate array (“FPGA”). Still further electronic components may be included within the first portion 110 to enable various features according to this disclosure.

[0050] While this example employs a wireless command to activate the firing circuit 112, in some examples, the device 100 may instead have a wired connection to another device, e.g, a biosensor, or may have a button or other wearer manipulatable device (“manipulandum”) to activate the firing circuit 112. [0051] Further, while the example shown in Figure 1 A has two portions 110,

120 that may be decoupled from each other, in some examples, the device 100 may be formed from a single portion that includes the components described above, or other components according to this disclosure. Thus, rather than providing a second portion 120 that is disposable and first portion 110 that is reusable, the entire device may be discarded.

[0052] Moreover, in some examples, the device 100 may include other combinations or sub-combinations of components that are formed separately, but can be coupled together to form the device 100. For example, the device 100 may have one unit that includes the second chamber 124 as a fluid cartridge that can be assembled to a separate unit that may be a needle cartridge including the first chamber 122 and third chamber 126, which may, for example, allow fluid cartridges to be discarded upon reaching an expiration date without also necessarily discarding a needle cartridge that may not be subject to the same timing constraints. Other combinations are also possible, including, but not limited to arrangements in which propellants are provided as cartridges or other form factors that may allow ready assembly when preparing for use without a risk of inadvertent activation of the device in transit between locations.

[0053] Referring now to Figure IB, Figure IB shows the device 100 after the propellants 142, 144 have been activated and the pistons 132, 134 driven to the opposite end of the chambers 122, 124. The first piston 132 has driven needle cap 150 and needle 152 so the needle 152 extends through the opposite end of the first chamber 122. The needle 152 has travelled through the needle guide 154, where it was bent towards the wearer’s skin. The second piston 134 has expelled the contents of the second chamber 124 through the fluid path 125, the void in the first piston 132, and the needle 152 into the wearer. Where movement of the first piston 132 and the needle cap 150 through the first chamber 122 may have imparted air movement through the second fluid path 127, the second vent 166 has allowed any corresponding pressure build-up to be vented, either by relieving pressure on the third piston 136 if present, or by directly venting any air moved ahead of the needle cap 150 or first piston 132 if the third piston 136 is omitted.

[0054] While in this example, the second piston 134 has been driven the full length of the second chamber 124, in some examples, a respective piston may only be driven part of the length of its chamber. For example, propellant may be sufficient to only drive the piston partway through a chamber, or one or more physical obstructions may be disposed within the chamber, or formed in the walls of the chamber to prevent the piston from travelling the full length of the chamber. Such a feature may be desirable to allow for a greater quantity of injectable material to be disposed within the second chamber 124 than is to be dispensed in a single dose. For example the second chamber 124 may store 1 ml of epinephrine, but one or more obstructions may permit the second piston 134 to expel only, for example, 0.3 ml of epinephrine. Such features may enable a more uniform manufacturing process or help ensure sufficient injectable material is injected, even in the event of a partial failure of the device, e.g ., the second propellant 144 only partially activates.

[0055] While the second piston 134 was driving the injectable material out of the second chamber 124, the first vent 162 in the first chamber 122 had been venting to dissipate the pressure generated by the first propellant 142. Such venting may prepare the device 100 for retracting the needle 152 by reducing a resistance to the needle cap 150 and/or piston 132 being moved back into the first chamber 122.

[0056] Referring now to Figure 1C, Figure 1C shows the device 100 after the third propellant 146 in the third chamber 152 has been activated and needle 152 has been retracted as a result. Specifically, the third piston 136 has been driven to the opposite end of the third chamber 126, which has generated a pressure increase in the second fluid path 127 to displace the needle cap 150 and first piston 132 backward in the first chamber 122 so the needle 152 is pulled back within the device 100. The first vent 162 had further allowed dissipation of pressure as the first piston 132 and needle cap 150 were pushed back toward the starting end of the first chamber 122.

[0057] While the example device 100 shown in Figures 1 A-1C has three chambers, any suitable number of chambers may be employed. For example, an example wearable emergency drug injection device may only have a single chamber, such as the first chamber 122 shown in Figure IB, e.g., with a retraction-inducing propellant positioned downstream of the extended position of the needle cap 150 to impart motion to push the needle cap 150 back in for retraction. Or a second portion 120 may have two or more chambers, each configured with a propellant and/or a piston and propellant to provide suitable functionality. Further, the device may include multiple needles to enable delivery of multiple doses, or doses of different types of injectable materials based on a received command. [0058] Moreover, while each chamber in the example device 100 shown in

Figures 1 A-1C has a respective piston, other arrangements with fewer or more pistons may be employed. For example, an example device may omit the third piston 136 in the third chamber and employ just the third propellant to generate pressure to move the needle cap 150 and/or the first piston 132 for achieving retraction. Or the first piston 132 and the needle cap 150 in the first chamber 122 may correspond to a single structure. Further, additional pistons may be added in series as desired, for example, to provide redundancy in case a seal about a particular piston fails.

[0059] Referring now to Figure 2, Figure 2 shows an example system for a wearable emergency drug injection device. In this example, the device 100 shown in Figures 1 A-1C receives a wireless command from remote device 200. The remote device 200, as described above, may be any suitable device with a wireless transmitter, such as a smartphone, smartwatch, blood pressure sensor, CGM, etc. Such remote devices may be handheld or wearable devices or larger devices, such one or more sensing systems as may be found in a hospital or other medical office. Suitable wireless communication mechanisms include Bluetooth®, Bluetooth® low-energy (“BLE”), WiFi, near-field communications (“NFC”), etc.

[0060] In one example, the remote device 200 is a CGM 200 that senses and stores glucose levels over time for the wearer. The glucose levels may be accessed wirelessly by various devices, such as the wearer’s smartphone, an insulin pump, or example wearable emergency drug injection devices according to this disclosure. In this example, the CGM 200 is configured with a glucose level threshold, below which the wearer is experiencing a hypoglycemic event. The CGM 200 may periodically measure the wearer’s glucose levels and compare them to the glucose level threshold. If a measured glucose level (or several consecutive measured glucose levels) falls below the glucose level threshold, the CGM 200 may determine a hypoglycemic event. In this example, the CGM 200 may issue an alert to the wearer, such as by transmitting a signal to the wearer’s insulin pump to trigger an audible alarm. The CGM 200 may also transmit a signal to the device 100 to cause it to deliver a dose of glucagon to the wearer.

[0061] In this example, the CGM 200 first transmits a signal to the wearer’s insulin pump, if the wearer has one, and continues to monitor the wearer’s glucose levels to detect whether they rise above the glucose level threshold. If the glucose levels rise above the glucose level threshold, it may indicate that the wearer has eaten some food and the hypoglycemic event has passed. However, if after a predetermined period of time, e.g ., 5 minutes, the hypoglycemic event continues or worsens, the CGM 200 may then determine intervention is needed and transmit the signal to the device 100 to cause a dose of glucagon to be injected into the wearer. Such an example may be desirable as it may allow the wearer to raise their glucose levels, even if they are unresponsive, e.g. , due to being asleep or unconscious. And while this example relates to a hypoglycemic event and a CGM, other biosensors may be employed as well or instead.

[0062] For example, blood pressure, ECG, blood oxygen, etc. biosensors may be employed in some examples to detect medical events, such as anaphylaxis, etc., which may then trigger the biosensor, or another device such as a smartphone, to transmit a signal to the device 100 to cause an injectable material, e.g. , epinephrine, naloxone, etc., to be injected into the wearer. Thus, different medical events may be addressed or mitigated automatically via the combination of the remote device 200 and the example wearable emergency drug injection device 100, which may address an emergency condition or may allow time for a full medical response to occur, if needed.

[0063] Referring now to Figure 3, Figure 3 shows a perspective view of an example needle guide 354 of a device 300. This perspectives show an example of the shape of the needle guide 354 and the bend formed in the needle 352 as it travels through the needle guide 354.

[0064] Referring now to Figure 4, Figure 4 is a graph showing pressure conditions for a chamber relative to which a needle can be extended and retracted. As noted previously, the device can include a venting arrangement that allows pressure changes that facilitate proper functioning of the needle extension and retraction.

Figure 4 illustrates how pressure conditions in the chamber may vary based on presence and size of a vent provided in the chamber.

[0065] For example, the pressure within the chamber behind the piston is shown at 410 beginning at an initial level. The initial level may be atmospheric pressure at 14.7 PSI (pounds per square inch), for example. An extension threshold 413 is shown by a horizontal dashed line and represents an amount of pressure sufficient to exert adequate force to move a piston forward to cause needle extension and insertion into a wearer’s skin, for example, for overcoming any pressurized resistance from pressure in front of the piston in the chamber or friction within the chamber or outside the chamber, e.g., friction from penetrating the wearer’s skin. A retraction threshold 415 is shown by another horizontal dashed line and represents an amount of pressure low enough to be overcome to allow the piston to move backward to cause needle retraction, for example, for overcoming pressurized resistance from pressure behind the piston in the chamber or friction within the chamber or outside the chamber, e.g., friction from movement within the wearer’s skin.

[0066] If no vent is provided, the pressure within the chamber behind the piston may follow the progression represented by the unvented line 420. In particular, after the pressure level starts at the initial pressure value at 410, the activation of an extension charge or propellant can cause a large increase 422 in pressure. This increase 422 may raise the pressure behind the piston above the extension threshold 413 such that the piston begins to move for extending the needle. Movement of the piston for extending the needle can cause an initial pressure drop 424, e.g., based on the volume behind the piston being increased due to the piston’s movement. However, following the initial pressure drop 424 and given the lack of a vent to allow further pressure reduction, the pressure level may remain at a static level 426 that may be substantially above the retraction threshold 415, such that activation of a retraction charge or propellant or other retractor in front of the piston will not generate adequate pressure to overcome the pressure already behind the piston from the earlier activation of the extension charge or propellant.

[0067] In comparison, if an appropriately sized vent is provided, the pressure within the chamber behind the piston may follow the progression represented by the vented line 430. The vent may be positioned behind the starting position of the piston or at a suitable position along the travel path of the piston to allow venting during the travel of the piston. In particular, after the pressure level starts at the initial pressure value at 410, the activation of an extension charge or propellant can cause a large increase 432 in pressure. This increase 432 may be slightly less than the increase 422 from the unvented 420 scenario (e.g., due to at least some small part of the generated pressure also being dissipated through the vent) but may still raise the pressure behind the piston above the extension threshold 413 such that the piston begins to move for extending the needle. Movement of the piston for extending the needle can cause an initial pressure drop 434, e.g., based on the volume behind the piston being increased due to the piston’s movement. Additionally, following the initial pressure drop 434, the vent can allow continued dissipation of the pressure to yield an additional pressure drop 436 that may allow the pressure behind the piston to fall below the retraction threshold 415, such that activation of a retraction charge or propellant or other retractor in front of the piston will generate adequate pressure to overcome the pressure already behind the piston from the earlier activation of the extension charge or propellant.

[0068] In contrast, if the vent is provided but is over-sized, the pressure within the chamber behind the piston may follow the progression represented by the over- vented line 440. In particular, after the pressure level starts at the initial pressure value at 410, the activation of an extension charge or propellant can cause an increase 442 in pressure. This increase 442 may be substantially less than the increase 422 from the unvented 420 scenario or the increase 432 from the vented 430 scenario (e.g., due to a significant part of the generated pressure being dissipated through the vent) and thus may fail to raise the pressure behind the piston above the extension threshold 413, with the result that the piston ultimately does not move for extending the needle. After the pressure peaks, the venting may continue to provide a pressure drop 446, which may allow the pressure behind the piston to fall below the retraction threshold 415, although such result may be moot given that the needle never extended in the first place.

[0069] Thus, appropriate sizing of the vent may facilitate proper functioning of the needle extension and retraction. The vent may be sized so that the venting permits pressure from the first pressure increase from activation of the extension propellant to dissipate before retracting the needle so that the second pressure increase from activation of the retraction propellant or other retractor is able to generate a pressure differential across the piston sufficient to move the piston back toward the first end of the chamber for retracting the needle. The vent size and/or propellants or other retractor elements may be selected so that the first pressure increase from activating the extension propellant is sufficiently high to cause the piston to move along the travel path from a first travel path position to a second travel path position notwithstanding the presence of the vent and the capacity of the vent to vent a portion of the first pressure increase during the extending. Additionally or alternatively, the vent size and/or propellants or other retractor elements may be selected so that the second pressure increase from the retraction propellant or other retractor is sufficiently high to overcome remaining pressure between the second travel path position and the first chamber end and cause the piston to move for the retracting. [0070] Although discussion above is primarily focused on venting relative to a chamber in which a piston is moving for extending or retracting a needle (e.g., such as with the first vent 162 in the first chamber 122), similar effects or progressions may be relevant with respect to venting relative to other chambers (e.g., such as with the second vent 166 in the third chamber 126). The relevance of the respective thresholds 413, 415 may switch in such instances. For example, if the third chamber 126 is unvented, the pressure therein may have similar characteristics to those illustrated by the unvented line at 420, and the third propellant 146 may be sufficient to push past a first pressure threshold 413 to overcome friction (e.g., from needle relative to the wearer’s skin and/or from the piston relative to the chamber walls) and/or overcome pressure on a back side of the piston to enable needle retraction, yet not allow adequate pressure relief to dip below a different pressure threshold 415 at another time for the first propellant 142 to overcome friction (e.g., from needle relative to the wearer’s skin and/or from the piston relative to the chamber walls) and/or overcome pressure on a front side of the piston to enable needle extension. In comparison, if the second vent 166 in the third chamber 126 is appropriately sized, the pressure in the third chamber 126 may have similar characteristics to those illustrated by the vented line at 430, e.g., where adequate pressure can be built-up to cross one threshold 413 to enable needle retraction while adequate venting is also available to allow pressure relief for dipping below a different pressure threshold 415 at another time to enable needle extension. In contrast, if the second vent 166 in the third chamber 126 is over sized, the pressure in the third chamber 126 may have similar characteristics to those illustrated by the over-vented line at 440, e.g., where insufficient pressure is generated to push past a first pressure threshold 413 so that retraction fails even though adequate venting is provided to allow dipping below a different pressure threshold 415 to allow extension.

[0071] Referring now to Figure 5, Figure 5 shows an end view of an example injection portion 500. The injection portion 500 includes caps 502, 504, 506 positioned at respective chamber ends, e.g., respectively over an ejection chamber, a dispenser chamber, and a retraction chamber. Each cap 502, 504, 506 includes a printed circuit board 511, 513, 515 bearing other elements. For example, each printed circuit board 511, 513, 515 includes respective electrical contacts 521, 523, 525, heating element mounts 531, 533, 535, and heating elements 551, 553, 555. The heating element mounts 531, 533, 535 may correspond to soldering pads or other suitable structure for supporting heating elements 551, 553, 555 (such as resistors) and/or providing connection between the heating elements 551, 553, 555 and the electrical contacts 521, 523, 525, which may provide connection to the firing circuit.

In use, the heating elements 551, 553, 555 may be used to activate propellants for driving pistons and/or otherwise introducing pressure within the respective chambers for providing their respective functions.

[0072] The caps 502, 506 that respectively bound the ejection chamber and the retraction chamber also have vents 562, 566. The vents 562, 566 may correspond to vias formed through the printed circuit boards 511, 515 and thus may be readily incorporated when manufacturing the device. The vents 562, 566 may correspond to unobstructed openings that will allow ongoing passive venting and thus may provide a more cost effective structure for venting than if additional components such as a flap or other structure for selectively sealing an orifice were instead incorporated and utilized.

[0073] The vents 562, 566 are sized to facilitate proper functioning of the needle extension and retraction. In one example, for printed circuit boards 511, 515 having an outer diameter of 0.22 inches (5.6 millimeters) placed over chambers having a volume behind the piston that expands from approximately 0.011 cubic inches (180 cubic millimeters) before extension to approximately 0.081 cubic inches (1327 cubic millimeters) after extension and for use in a sequence in which retraction is triggered 1.5 seconds after extension is triggered, initial testing indicated that retraction was prevented when vents were not provided, while unobstructed openings with sizes of 0.15 mm, 0.20 mm, 0.25 mm, and 0.30 mm allowed needle extension and retraction, while opening sizes of 0.35 and larger failed to achieve extension.

Thus, while an unobstructed opening size of between 0.15 mm and 0.30 mm across was shown to be effective at the tested parameters, a more conservative range of between 0.20 mm and 0.25 mm across may provide greater confidence in operations notwithstanding other potential variances in other parameters, while a slightly more encompassing range of between 0.1 mm and 0.35 mm across may nevertheless be suitable for arrangements in which variations are introduced for other parameters such as time intervals, component dimensions, or propellants used.

[0074] Referring now to Figures 6A-6D, these figures show different views of an example injection portion 600 at different times during activation. The injection portion 600 defines three chambers 622, 624, 626. A respective piston 632, 634 is positioned within each of the first and second chambers 622, 624, while the third chamber 626 is depicted without a corresponding piston. The respective pistons 632, 634 are movable within the respective chambers 622, 624 among travel path positions, such between a first travel path position at a starting or origin chamber end as shown in FIG. 6A and a second travel path position at finishing or terminus chamber end in FIG. 6C. A first vent 662 is defined through an end wall of the first chamber 622 behind the first piston 632, and a second vent 666 is defined through an end wall of the third chamber 626. Respective propellants 642, 644, 646 are positioned at origin ends of each of the chambers 622, 624, 626. A first fluid path 625 is defined by an outlet from the second chamber 624 to the first chamber 622 and is shown in Figure 6A obstructed by a needle cap 650. A second fluid path 627 provides fluid communication between the third chamber 626 and the first chamber 622 at the terminus end of the first chamber 622.

[0075] A hollow needle 652 is positioned to move in response to movement of the first piston 632. For example, the hollow needle 652 may be borne by a secondary side of the piston 632 such that pressure exerted behind the piston 632 on a primary side opposite the secondary side of the piston 632 will drive the needle 652 in a direction for extending out of the injection portion 600. The needle 652 in this example is hollow to allow injectable material to flow through the needle 652 and into the wearer. In addition, the needle 652 is constructed from a flexible material, such as a suitable plastic or metallic material, such as Nitinol. The needle 652 in this example is sufficiently flexible that it can bend at an angle of between 30 to 45 degrees without permanently deforming and while maintaining a fluid path through the needle. A needle guide 654 is positioned to guide the needle 652 during extension, for example, to force the needle 652 to bend toward the wearer’s skin in use.

[0076] Figure 6A shows the injection portion 600 before it has been activated.

The two pistons 632, 634 are at rest at one end (e.g., an origin or starting end) of the respective chamber 622, 624. The needle cap 650 seals a fluid port between the first chamber 622 and the second chamber 624, and the needle 652 is entirely contained within the injection portion 600.

[0077] When the first propellant 642 behind the first piston 632 is activated, pressure is generated behind the first piston 632. A relatively small portion of such pressure may be vented through the first vent 662, yet the generated pressure may nonetheless drive the first piston 632 across the first chamber 622 (e.g., to the position shown in Figure 6B). For example, the pressure generated on the back of the first piston 632 from first propellant 642 may be sufficient to overcome any overpressure in front of the first piston 632, as well as frictional forces, such as from interaction of the first piston 632 with the walls of the first chamber 622 and/or interaction of the needle 652 with the wearer’s skin. The first vent 662 may allow venting while the first piston 632 is moving during extension of the needle 652, and may continue to vent after extension of the needle 652 is completed to dissipate residual overpressure from the first propellant 642 (e.g., which may later facilitate retraction of the needle 652, as described further below).

[0078] The movement of the first piston 632 across the first chamber 622 can also push air or other fluid in front of the first piston 632. This may generate pressure in front of the first piston 632, e.g., which may cause the needle cap 650 to displace before being contacted by the first piston 632. As the first piston 632 moves across the first chamber 622, pressure in front of the first piston 632 may vent out through the second fluid path 627, the third chamber 626, and the second vent 666. For example, the movement of the first piston 632 across the first chamber 622 may cause the needle cap 650 to move past a port for the second fluid path 627 and so that the second fluid path 627 becomes unblocked and exposed so venting can occur through the second fluid path 627. Overall, venting through the second vent 666 may reduce pressurized resistance in front of the first piston 632 and thus allow pressure generated from the first propellant 642 to move the first piston 632 more easily, e.g., which may allow a smaller amount of the first propellant 642 to be used and/or reduce a chance that pressure from the first propellant 642 will be inadequate to extend the needle 652 in light of venting also occurring behind the first piston 632 through the first vent 662.

[0079] Referring now to Figure 6B, the first propellant 642 behind the first piston 632 has been activated, which has driven the first piston 632 across the first chamber 622 into contact with the needle cap 650. This movement has forced the needle 652 through the needle guide 654, which bends the needle 652. This movement has also driven needle cap 650 out of its initial position (e.g., to a position against the needle guide 654), thereby unsealing the fluid port between the first chamber 622 and the second chamber 624. An opening in the first piston 632 aligns with the fluid port, providing the first fluid path 625 from the second chamber 624 through the fluid port, the void in the first piston 632 and into the needle 652. At this time, however, the propellant behind the second piston 634 has not yet been activated, thus the contents of the second chamber 624 have not yet been forced through the fluid port by the second piston 634.

[0080] Referring now to Figure 6C, the second propellant 644 behind the second piston 634 has been activated, which drove the second piston 634 to the opposite end of the second chamber 624, thereby forcing the contents of the second chamber 624 through the fluid port and ultimately into and through the needle 652.

For example, suitable injectable substances may include epinephrine, naloxone, glucagon or a glucagon activation solution, or other drugs or chemicals.

[0081] While the second piston 634 is moving to force the contents of the second chamber 624 through the needle 652, pressure behind the first piston 632 may continue to dissipate by venting through the first vent 662 behind the first piston 632. This may reduce pressurized resistance behind the first piston 632 and facilitate subsequent movement back toward the origin end of the first chamber 622 for retraction of the needle 652.

[0082] When the third propellant 646 in the third chamber 626 is activated, pressure is generated in front of the first piston 632. A relatively small portion of such pressure may be vented through the second vent 666, yet the generated pressure may nonetheless drive the first piston 632 backward across the first chamber 622 toward its original starting point (e.g., to the position shown in Figure 6D). For example, the pressure generated on the front of the first piston 632 from the third propellant 646 may be sufficient to overcome any residual overpressure from the first propellant 642 behind the first piston 632, as well as frictional forces, such as from interaction of the first piston 632 with the walls of the first chamber 622 and/or interaction of the needle 652 with the wearer’s skin. Overall, although the second vent 666 may be sufficiently large to allow venting at relatively lower pressures and/or a greater duration of time during and following extension of the needle 652, the size of the second vent 666 may also be sufficiently small to prevent over-venting at relatively higher pressure and/or shorter duration in effect from activation of the third propellant 646 and thus prevent disabling of retraction of the needle 652.

[0083] Referring now to Figure 6D, the propellant in the third chamber 126 has been activated, which has driven the first piston 632 back toward the origin end of the first chamber 622, so that the needle 652 is once again entirely contained within the injection portion 600. [0084] Additionally, while the first piston 632 is moving backward across the first chamber 622 toward its original position, the first vent 662 may allow additional venting that may reduce pressurized resistance against the retracting motion of the first piston 632. Overall, although the first vent 662 may be sufficiently large to allow venting at relatively lower pressures and/or a greater duration of time leading up to and during retraction of the needle 652, the size of the first vent 662 may also be sufficiently small to prevent over-venting at relatively higher pressure and/or shorter duration in effect from activation of the first propellant 642 and thus prevent disabling of the initial extension of the needle 652.

[0085] Referring now to Figure 7, Figure 7 shows an example application of a wearable emergency drug injection device 700 (or device 700) according to this disclosure. As discussed above, the device 700 may be worn by a person to enable on- demand injection of an injectable material in to the wearer. In this example, the device 700 is attached to a strap 710, which the wearer has wrapped around their upper arm. Thus, if the device 700 is activated, such as by a wireless signal from a remote device or based on wearer interaction with a manipulandum on the device 700 or strap 710, the device 700 may inject a needle into the wearer’s arm and inject the injectable material through the needle, thereby delivering a dose of the injectable material.

[0086] While the example shown in Figure 7 is of an armband form factor, other example wearable configurations are within the scope of this disclosure. The strap 710 may hold the device 700 in place relative to a wearer, such as to an arm, leg, torso, or other body part. For example, the device 700 may be attached to a wristband, or adhered to the wearer by a tape or an adhesive applied to one side of the device 700. In some examples, the features of the device may be incorporated into another wearable device, such as an insulin pump, smartwatch, etc. Still further configurations to enable wearing of the device 700 against the wearer’s skin are within the scope of this disclosure.

[0087] Referring now to Figure 8, Figure 8 shows an example method 800 for use of a wearable emergency drug injection device. The method 800 will be described with respect to the device 100 shown in Figure 1 and the system shown in Figure 2; however, any suitable device or system according to this disclosure may be employed, such as the example devices shown in Figures 6A-6D.

[0088] At block 810, the device 100 receives an activation signal. In this example, the device 100 receives a wireless signal from the remote device 200 via a BLE wireless signal. To send the activation signal, the remote device 200 may first establish a communications connection with the device 100, such as by pairing with the device using the BLE protocol and then authenticating itself to the device 100, e.g ., by providing an encrypted communication comprising a digital signature or certificate. After establishing communications and authenticating itself to the device 100, the remote device 200 transmits an activation signal, which may comprise a command. And while in this example, the remote device 200 authenticates itself to the device 100, such a feature is not required. Instead, the remote device 200 may simply transmit an activation signal, such as by broadcasting an activation signal.

[0089] At block 820, in response to receiving the activation signal, the device

100 activates the first propellant 142 to force the first piston 132 towards the opposite end of the first chamber 122. In this example, the firing circuit 112 closes a switch to discharge a capacitor onto an electrical contact coupled to the first propellant 142. The electrical discharge from the capacitor ignites the first propellant 142, which then burns or explodes. The first piston 132 then traverses a portion of the first chamber 122 and forces the needle 152 through the needle guide 154. If a patient is wearing the device 100, the needle is also injected into the wearer’s skin.

[0090] In some examples, a series of activation signals may be transmitted to the first propellant 142. For example, the first propellant 142 may include multiple propellant components, each of which may be individually activatable. By activating these propellant components in sequence, a suitable pressure curve may be generated over time.

[0091] At block 822, in response to the activation of the first propellant 142, the first end of the first chamber 122 (e.g., the end behind the first piston 132) begins venting generated pressure through the first vent 162 and dissipating pressure generated from the activation of the first propellant 142. The activation of the first propellant 142 at block 820 may force the first piston 132 toward the opposite end of the first chamber 122 at block 820 notwithstanding the venting occurring at block 822. The venting at block 822 may continue during one or more subsequent acts in the method 800. The venting at block 822 can allow pressure behind the first piston 132 to drop below a retraction threshold 415 (Figure 4) and allow subsequent retraction of the needle 152 into the device 100.

[0092] At block 826, also in response to the activation of the first propellant

142, the second end of the first chamber 122 (e.g., the end in front of the first piston 132 in the direction of travel of the first piston 132 when extending the needle 152) begins venting generated pressure through the second vent 166 and dissipating pressurized resistance to the travel of the first piston 132 in the direction of extending the needle 152. The venting at block 824 may thus facilitate travel of the first piston 132 toward the opposite end of the first chamber 122 at block 820. For example, the venting at block 826 can reduce pressure in front of the first piston 132 so that pressure behind the first piston 132 can exceed the extension threshold 413 (Figure 4) and cause movement of the first piston 132 for extending the needle 152 from the device 100. The venting at block 826 may continue during one or more subsequent acts in the method 800.

[0093] At block 830, subsequent to activating the first propellant, the device

100 activates the second propellant 144 to force the second piston 134 towards the opposite end of the second chamber 124. In this example, the firing circuit 112 closes a switch to discharge another capacitor onto an electrical contact coupled to the second propellant 144. The electrical discharge from the capacitor ignites the second propellant 144, which then bums or explodes, generally as described above with respect to block 820. The second piston 134 then traverses a portion of the second chamber 124 and forces the injectable substance to flow out through the needle 152. If a patient is wearing the device 100, injectable material in the first chamber 122 and/or the second chamber 124 is dispensed into the wearer. As discussed above with respect to block 820, in examples where the second propellant 144 includes multiple individually-activatable propellant components, multiple actuation signals maybe transmitted to activate the propellant components in sequence to create a suitable pressure curve for driving the piston.

[0094] At block 840, the device 100 retracts the needle 152. In this example, subsequent to activating the second propellant 144, the device 100 activates the third propellant 146 to force needle cap 150 and/or the first piston 132 in a reverse direction away from the opposite end and toward the origin end of the first chamber 122. In this example, the firing circuit 112 closes a switch to discharge a capacitor onto an electrical contact coupled to the third propellant 146. The electrical discharge from the capacitor ignites the third propellant 146, which then bums or explodes. The resulting pressure generated forces the first piston 132 and/or needle cap 150 to traverse back across a portion of the first chamber 122 and pulls the needle 152 back into the device 100. The resulting pressure can impart such motion of the first piston 132 and/or needle cap 150 notwithstanding that a portion of the pressure may be vented through the second vent 166. If a patient is wearing the device 100, the needle is also retracted from the wearer’s skin.

[0095] The activation of propellant 3 at block 840 may be timed to allow adequate venting of the first end of the chamber performed at block 822. This may include incorporating a delay among other portions of the process. For example, a delay may be incorporated between when injecting will be completed and when retraction is triggered. Thus, the venting of the first end of the chamber at block 822 may primarily occur while injection is being performed or before injection is completed. Additionally or alternatively, the venting of the first end of the chamber at block 822 may include a segment of venting after the injecting is completed (e.g., which may occur during an incorporated delay between when injection is completed and when retraction is triggered).

[0096] In another example, at block 840, springs are compressed by the movement of the needle cap 150, and after sufficient gasses have been exhausted from the first chamber 122 and the chamber pressure drops below the force exerted by the springs, the needle 152 is retracted. Such springs may be provided alone or assisted by a propellant.

[0097] Still further needle retraction mechanisms may be employed in various examples. In various examples, needle retraction may be facilitated by the presence of the first vent 162 and the venting of the first end of the chamber at block 822 to dissipate pressurized resistance to retracting motion of the first piston 132, needle cap 150, and/or needle 152 provided by a suitable retraction mechanism.

[0098] It should be appreciated that block 840 is optional. Thus, the needle

152 may not be automatically retracted by the device 100. Instead, the wearer may manually retract the needle 152, or may remove the device 100 to withdraw the needle 152 from their skin.

[0099] Figure 9A-9B shows an example wearable emergency drug injection device 900 according to this disclosure. The device 900 may also represent other devices according to this disclosure. In some examples, the device 900 may utilize inductive coupling to trigger an action within a sequence for performing an injection. Implementing inductive coupling may provide various benefits in comparison to arrangements that utilize mating electrical contacts to transfer power or signals. For example, whereas electrical contacts may be subject to issues of fouling (e.g., the contacts may corrode or otherwise become fouled in a manner that may block adequate unobstructed connection to permit electrical travel) and/or misalignment (e.g., the contacts may fail to establish electrical connection if minor mismatches in alignment occur), such issues may be mitigated or eliminated by use of inductive coupling.

[00100] Referring to FIG. 9A, the device 900 includes two portions: a first portion 902 and a second portion 904. The first portion 902 and the second portion 904 may correspond to different portions of a housing of the device 900. In some examples, the first portion 902 and the second portion 904 may be releasably coupled together or otherwise readily separable from each other. For example, the second portion 904 may be a disposable portion (e.g., with a needle and/or expendable reservoir of injectable material) while the first portion 902 may correspond to a re usable portion (e.g., with a firing circuit, power source, or other electronic

components). In some examples, the first portion 902 and the second portion 904 may be integrally formed together or otherwise not readily separable.

[00101] The device 900 can include elements to permit wireless

communication between the first portion 902 and the second portion 904. For example, the first portion 902 includes a transmitter 906 and the second portion 904 includes a receiver 908. The transmitter 906 and the receiver 908 may each include a respective coil. The transmitter 906 and the receiver 908 in use may be spaced apart from one another yet nevertheless in sufficient proximity so that the transmitter 906 can induce current through the receiver 908 without contact between the transmitter 906 and the receiver 908.

[00102] The transmitter 906 may be electrically coupled with a control circuit 911, for example, which may include a power source 912 and a gating or switching mechanism 914, such as a transistor, operable to adjust whether and/or how much power is provided from the power source 912 to the transmitter 906. In operation, the control circuit 911 may apply power from the power source 912 to the transmitter 906 to induce current travel through the receiver 908.

[00103] As previously noted, the receiver 908 may be in the second portion 904 of the device 900. The second portion 904 of the device may also include an assembly 916 that may include a propellant 918 and an activator 920 for the propellant 918.

The propellant 918 may correspond to other propellants of other devices according to this disclosure. For example, the propellant 918 may correspond to a propellant used to cause a needle to extend or retract or a propellant used to cause an injectable to move through an extended needle. The activator 920 may include a resistor or other suitable structure capable of causing the propellant 918 to ignite. Alternatively, the activator 920 may be the receiver coil 908 itself, which is inductively heated by the transmitter coil 906. The receiver 908 may be coupled with the assembly 916 to cause the propellant 918 to ignite in response to current travel through the receiver 908, for example, in response to current travel being induced in the receiver 908 by power provided to the transmitter 906.

[00104] Although FIG. 9A shows a single transmitter 906 paired with a single receiver 908 relative to a single propellant 918, other arrangements are possible. In some examples, multiple propellants 918 may be employed and each may be associated with a separate respective transmitter 906 and receiver 908 pair (e.g., a first pair to activate a first charge to extend a needle, and a second pair to activate a second charge to drive the medication through the extended needle, along with a third pair to activate a third charge to retract the needle). In some examples, an array of transmitters 906 may be spatially aligned relative to an array of receivers (e.g., such that selecting a specific transmitter 906 to operate can activate a specific

corresponding receiver 908). In some examples, a single pair might be used to cause successive activation of different charges (e.g., by use of a multiplexor to route respective signals from the receiver 908 or by use of different segments of the receiver 908 that may respond to different segments or frequencies of the transmitter 906). In some examples, a single transmitter 906 may be used to selectively activate from among multiple different receivers 908 (e.g., to respectively activate different propellants 918), such as by use of receivers 908 that are configured to resonate at different frequencies and driving the transmitter 906 at different frequencies depending on which receiver 908 is to be activated. In some examples, some combination of spatial and frequency selection may be utilized, e.g., which may enable greater selectivity among receivers 908 and/or allow design variations based on a tradeoff between cost and selectivity.

[00105] Referring now to Figure 9B, Figure 9B shows a more detailed view of an example of the device 900. For example, in FIG. 9B, the control circuit 911 is shown having batteries 912A for power source 912 and a switch 914A for the gating mechanism 914. However, the control circuit 911 is not so limited and may include other forms of power source 912 (including, but not limited to capacitors) and/or gating mechanism 914 (including, but not limited to transistors, operational amplifiers, power amplifiers (e.g., that may affect power level), digital-to-analog converter (DAC) outputs, digital gates, relays, magnetic switches, sensors (e.g., acoustic, piezo, thermistor, photovoltaic), or other circuit block). Additionally, by way of illustration, the circuit 911 in FIG. 9B is shown having a DC to AC converter 930, e.g., which may be used to provide a time-varying current signal for inductive power transfer. By way of further illustration, the circuit 911 in FIG. 9B is shown having a power amplifier 932, e.g., which may in use may adjust a power level to a suitable level for use upon transmission to the second portion 904 of the device 900.

[00106] As previously noted, the transmitter 906 and receiver 908 may be coils or other structures that may be inductively coupled to one another (e.g., mutually coupled, as denoted by the letter M in FIGS. 9A and 9B). The receiver 908 may have an impedance tuned to match circuitry associated with the transmitter 906. For example, the receiver 908 is shown in FIG. 9B coupled with a capacitor 934 or other suitable element that may allow tuning the capacitance to tune the corresponding impedance.

[00107] In FIG. 9B, the assembly 916 of the second portion 904 is shown having a resistor 920A as the activator 920 for the propellant 918. For example, the resistor 920 A may output heat in response to current travel induced through the receiver 908 from the transmitter 906. However, the second portion 904 is not so limited and may include other forms of activator 920 (including, but not limited to a spark source or a laser or other light source). Further, in some examples, the activator 920 may be the receiver coil itself 908, which may be inductively heated by a varying electromagnetic field output by the transmitter coil 906. Moreover, although FIG. 9B diagrammatically shows the receiver 908 and resistor 920A as separate structures, in some embodiments, a single structure may act as the functional equivalent of both. For example, the receiver 908 itself may output heat in response to current induced therein.

[00108] FIG. 9B also shows a piston 938 movable by the propellant 918. The piston 938 may correspond to other pistons of other devices according to this disclosure. For example, the piston 938 may correspond to a piston used to cause a needle to extend or retract or a piston used to cause an injectable to move through an extended needle. Moreover, although the piston 938 is shown in FIG. 9B, in some examples, the piston 938 may be omitted, such as if the propellant 918 is used to create a pressure change to achieve a particular outcome without a corresponding piston 938.

[00109] The transmitter 906 and the receiver 908 may include any suitable structure for providing the described functions. As noted previously, in some examples, the transmitter 906 and/or the receiver 908 may correspond to a coil. In some examples, the transmitter 906 and/or the receiver 908 may correspond to a printed structure, e.g., formed by techniques for forming a printed circuit board (PCB). In some examples, the transmitter 906 and/or the receiver 908 may include one or more conductive traces.

[00110] In some examples, various parameters may affect an amount of power transferrable by inductive coupling between the transmitter 906 and the receiver 908. Examples may include (1) a frequency of power provided to the transmitter 906; (2) a number of turns in a coil of the transmitter 906 and/or the receiver 908; (3) a weight or gauge or thickness of a trace or wire; or (4) a width of trace or wire. For example, while a wire with a circular cross sectional may have a thickness and width that are the same, the thickness and width in a PCB trace may be different and both relevant to how much of received power is converted to heat (e.g., both thickness and width may have a second order effect on the inductive power transfer but a first order effect on the electrical-to-heat conversion).

[00111] In some examples, power provided by batteries 912A may be adequate to allow adequate power to be transferred through inductive coupling to the receiver 908 for activating the propellant 918. In some examples, however, batteries 912A may be supplemented and/or replaced at least in part with capacitors or other elements of a charge pump circuit, for example, to raise a current level above a discharge current level available from one or more batteries 912A.

[00112] Any suitable materials may be used in the device 900. In some examples, a ceramic PCB or other a heat resistant substrate may be utilized in the first portion 902 or the second portion 904, for example, to promote durability and/or longevity of parts, such as if being used as re-usable components. In some examples, an amount of metal incorporated into the second portion 904 to enable power transmission through inductive coupling may be significantly less than if electrical contacts were instead included for power transmission through direct contact. Such lower metal consumption may be beneficial for multiple reasons, such as reducing an overall cost of production and/or reducing an environmental impact of disposable parts that may ultimately end up in a landfill or other disposal location. Nevertheless, components for facilitating power transfer through inductive coupling need not be mutually exclusive to components for establishing direct electrical connection or other techniques. For example, multiple systems for power transfer between the first portion 902 and the second portion 904 may be incorporated for redundancy or other reasons.

[00113] Referring now to Figure 10, Figure 10 shows an example method 1000 for using a wearable emergency drug injection device according to this disclosure.

The method 1000 will be described with respect to the device 900 shown in Figures 9A and 9B and the system shown in Figure 2; however, any suitable device or system according to this disclosure may be employed.

[00114] At block 1010, the device 900 receives an activation signal. In this example, the device 900 receives a wireless signal from the remote device 200 via a BLE wireless signal. To send the activation signal, the remote device 200 may first establish a communications connection with the device 900, such as by pairing with the device using the BLE protocol and then authenticating itself to the device 900, e.g ., by providing an encrypted communication comprising a digital signature or certificate. After establishing communications and authenticating itself to the device 900, the remote device 200 transmits an activation signal, which may comprise a command. And while in this example, the remote device 200 authenticates itself to the device 900, such a feature is not required. Instead, the remote device 200 may simply transmit an activation signal, such as by broadcasting an activation signal.

[00115] In some examples, an activation signal may be generated by manual means, such as by pressing a button or flipping a switch to connect the power supply 912A to the DC to AC converter 930 to generate a current in the transmission coil 906. Still further activation techniques according to this disclosure may be employed in some examples.

[00116] At block 1020, in response to receiving the activation signal, the device 900 wirelessly transfers power through an inductive coupling. For example, the device 900 may transfer power from the transmitter 906 to the receiver 908 in response to the control circuit 911 providing power to the transmitter 906. In this example, the firing circuit 911 closes a switch 914A to cause current to discharge from the batteries 912A and through the DC to AC converter 930 and power amplifier 932A to provide a time-varying current through the transmitter 906 to induce a current to flow in the receiver 908 (e.g., due to inductive coupling between the transmitter 906 and receiver 908).

[00117] At block 1030, in response to the power transferred to the receiver 908 from the transmitter 906, the activator 920 (e.g., the receiver coil 980 itself or resistor 920A) heats and ignites the propellant 918, which then burns to generate pressure. Pressure from the ignition of the propellant can cause a corresponding action, such as causing a needle to extend or retract or an injectable to move through an extended needle.

[00118] The foregoing description of some examples has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the disclosure. For example, more or fewer steps of the processes described herein may be performed according to the present disclosure. Moreover, other structures may perform one or more steps of the processes described herein.

[00119] Reference herein to an example or implementation means that a particular feature, structure, operation, or other characteristic described in connection with the example may be included in at least one implementation of the disclosure. The disclosure is not restricted to the particular examples or implementations described as such. The appearance of the phrases“in one example,”“in an example,” “in one implementation,” or“in an implementation,” or variations of the same in various places in the specification does not necessarily refer to the same example or implementation. Any particular feature, structure, operation, or other characteristic described in this specification in relation to one example or implementation may be combined with other features, structures, operations, or other characteristics described in respect of any other example or implementation.

[00120] Use herein of the word“or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and all three of A and B and C.

Claims

CLAIMS That which is claimed is:

1. A method of controlling injection device needle positioning, the method comprising:

extending a needle out of a body of an injection device by movement of a piston bearing the needle from a first travel path position at a first end of a chamber to a second travel path position toward a second end of the chamber, the movement of the piston in response to activation of an extension propellant that generates a first pressure increase between the first end of the chamber and a first side of the piston; and

retracting the needle into the body of the injection device by additional movement of the piston bearing the needle from the second travel path position toward the first end of the chamber and in response to activation of a retraction propellant that generates a second pressure increase between the second end of the chamber and a second side of the piston opposite the first side of the piston.

2. The method of claim 1, further comprising venting at least a portion of the first pressure increase through a vent positioned between the first end of the chamber and the first travel path position or positioned through an end wall at the first end of the chamber.

3. The method of claim 1, wherein at least a portion of the venting occurs while the piston is moving to extend the needle out of the body of the injection device.

4. The method of claim 1, further comprising:

dispensing a medication through the needle between the extending and the retracting of the needle.

5. The method of claim 4, wherein the dispensing is in response to activation of a dispenser propellant that generates a dispensing pressure increase to move a dispensing piston from a first end of a dispensing chamber toward a second end of the dispensing chamber, the dispensing chamber in fluid communication with the needle when the piston is at the second travel path position.

6. A system for controlling injection device needle positioning, the system comprising:

a piston;

a needle movable in response to movement of the piston;

a chamber bounded by chamber walls, having a first end and a second end, and sized to receive the piston therein for travel along a travel path including a first travel path position and a second travel path position;

an extender positioned proximate the first end of the chamber and comprising an extension propellant activatable to produce a first pressure at the first end of the chamber to move the piston from the first travel path position toward the second travel path position to cause the needle to extend;

a retractor positioned proximate the second end of the chamber and operable to generate retracting movement of the piston from the second travel path position toward the first travel path position to cause the needle to retract; and

a vent to dissipate at least a portion of the first pressure and defined through a chamber wall in a portion of the chamber defined between the first travel path position and the first end of the chamber.

7. The system of claim 6, wherein the retractor comprises a retraction propellant activateable to produce a second pressure at the second end of chamber to impart movement of the piston from the second travel path position toward the first travel path position.

8. The system of claim 6, further comprising a dispenser comprising:

a dispenser chamber, the dispenser chamber in fluid communication with the needle when the piston is at the second travel path position;

a dispenser piston positioned at a first end of the dispenser chamber;

a medication disposed in the dispenser chamber between the dispenser piston and a second end of the dispenser chamber; and

a dispenser propellant activatable to move the dispenser piston from the first end of the dispenser chamber toward the second end of the dispenser chamber to drive the medication through the needle.

9. The system of claim 8, wherein the piston at the second travel path position establishes fluid communication between the dispenser chamber and the needle.

10. The system of claim 6, wherein the vent is formed at least in part in a printed circuit board that comprises electronics for activating the extension propellant.

11. The system of claim 6, wherein the vent is a first vent, and wherein a second vent is defined in communication with the second end of the chamber.

12. The system of claim 6, wherein the extender comprises an activator for activating the extension propellant, wherein the activator comprises a heat source or a spark source, and wherein the extension propellant comprises nitrocellulose.

13. The system of claim 6, wherein the vent is an unobstructed opening.

14. The system of claim 13, wherein the unobstructed opening is between 0.1 mm and 0.35 mm across.

15. The system of claim 13, wherein the unobstructed opening is between 0.15 mm and 0.30 mm across.

16. The system of claim 13, wherein the unobstructed opening is between 0.20 mm and 0.25 mm across.

17. An auto-injector device, comprising:

a first chamber having a first origin end and a first terminus end;

a first piston positioned within the first chamber, the first piston having a primary side and a secondary side, the first piston bearing a hollow needle on the secondary side such that the needle is movable by the first piston to extend through the first terminus end of the first chamber, and the first piston defining a laterally- facing conduit defining a fluid path to the hollow needle;

a second chamber having a second origin end and a second terminus end, the second chamber containing medication, and the second chamber defining an outlet at the second terminus end; a second piston positioned within the second chamber and proximate the second origin end, the second piston moveable to force the medication out of the second chamber through the outlet of the second chamber;

a third chamber having a third origin end and a third terminus end and in fluid communication through the third terminus end with the secondary side of the first piston;

a first cap positioned at the first origin end of the first chamber and having a first vent and a first heat source;

a first propellant positioned in the first chamber and between the first heat source and the first piston;

a second cap positioned at the second origin end of the second chamber and having a second heat source;

a second propellant positioned in the second chamber and between the second heat source and the second piston;

a third cap positioned at the third origin end of the third chamber and having a third heat source;

a third propellant positioned in the third chamber and between the third heat source and the third terminus end;

a processor configured to:

at a first time, trigger the first heat source for activating the first propellant to exert fluid pressure on the first piston to cause the needle to extend out the first terminus end of the first chamber and cause the laterally- facing conduit of the first piston to align with the outlet of the second chamber;

at a second time after the first time, trigger the second heat source for activating the second propellant to exert fluid pressure on the second piston to cause the second piston to send the medication through a fluid passage defined by the aligned outlet, laterally-facing conduit, and needle; and

at a third time after venting of pressure build-up within the first chamber between the first cap and the primary side of the first piston, trigger the third heat source for activating the third propellant to exert fluid pressure on the secondary side of the first piston to overcome pressure dissipated on the primary side of the first piston through the first vent and urge the first piston toward the first origin end of the first chamber to retract the needle.

18. The auto-injector device of claim 17, wherein the third cap defines a second vent arranged to allow pressure dissipation from within the third chamber to reduce pressurized resistance to movement of the first piston and extension of the needle resulting from activation of the first propellant.

19. The auto-injector device of claim 17, wherein the second time and the third time are separated by an interval configured to permit delivery of a predetermined amount of the medication.

20. The auto-injector device of claim 17, wherein the second time and the third time are separated by a first interval configured to permit delivery of a predetermined amount of the medication and a second interval configured to permit venting after cessation of delivery of the predetermined amount of the medication.

21. The auto-injector device of claim 17, further comprising:

a receiver coil;

a transmitter coil inductively couplable with the receiver coil; and

a power source electrically coupled to the transmitter via a control circuit, wherein the control circuit applies power to the transmitter coil to induce current in the receiver coil, and wherein the current induced in the receiver coil triggers:

the first heat source for activating the first propellant to cause the needle to extend;

the second heat source for activating the second propellant to cause the medication to flow through the needle; or

the third heat source for activating the third propellant to cause the needle to retract.

22. The auto-injector device of claim 21, wherein the receiver coil comprises: the first heat source;

the second heat source; or

the third heat source.

23. The auto-injector device of claim 21, wherein the receiver coil is coupled with a resistor that produces heat in response to the current induced in the receiver coil, wherein the resistor corresponds to:

the first heat source;

the second heat source; or

the third heat source.