DE102016207255A1 - Injection device for injecting a fluid and method for determining a dose of a fluid - Google Patents

Abstract

The invention relates to an injection device (100) for injecting a fluid. The injection device (100) comprises a housing (110) which has a shaft receiving section (112) and / or a housing stop (114) with at least one opening (116), a metering device (102) for metering the fluid, wherein the metering device (102 ) has a shank (104) movably disposed in the shank receiving portion (112) and a dose button (103) for moving the shank (104), and a measuring element (108) for detecting a dose of the fluid. The measuring element (108) is designed as an impedance measuring element, in particular wherein the measuring element (108) is designed to change a length of a coil winding and / or an electrical conductor upon actuation of the Dosisknopfs (103).

Description

State of the art

The invention is based on a device or a method according to the preamble of the independent claims. The subject of the present invention is also a computer program.

The lack of endogenous insulin in diabetes mellitus can be treated today by injecting an insulin preparation. Common methods of injection are, for example, disposable syringes, permanent insulin pumps and disposable and reusable pens. The pens can resemble a thick ballpoint pen and be populated with so-called insulin spools. The required amount of insulin can be adjusted by turning a dose button.

Disclosure of the invention

Against this background, with the approach presented here, an injection device for injecting a fluid, a method for determining a dose of a fluid, furthermore a device which uses this method, and finally a corresponding computer program according to the main claims are presented. The measures listed in the dependent claims advantageous refinements and improvements of the independent claim device are possible.

An injection device for injecting a fluid is presented, wherein the injection device has the following features:
a housing having a shaft receiving portion and / or a housing stopper with at least one opening;
a metering device for metering the fluid, wherein the metering device has a shaft movably arranged in the shaft receiving portion or can be arranged and a Dosisknopf for moving the shaft; and
a measuring element for determining a dose of the fluid, wherein the measuring element is formed as an impedance measuring element, in particular wherein the measuring element is designed to change a length of a coil winding and / or an electrical conductor upon actuation of the dose button.

According to an advantageous embodiment, the measuring element may extend at least in sections between the dose button and the shaft receiving portion on the shaft and be designed to be displaced during movement of the shaft such that a length of the measuring element between the dose button and the shaft receiving portion changes, and / or wherein the measuring element extends at least in sections between the dose button and the housing stop and is designed to be rotated during movement of the shaft through the opening such that a number of turns and / or a length of the measuring element between the dose button and the housing stop changes.

An injection device can be understood as an apparatus for simply injecting a certain amount of a fluid, in particular into a human body. The fluid may in particular be a medicament. For example, the injection device may be realized as insulin pen for injecting insulin. The housing may be, for example, an elongate sleeve. The Dosierknopf can be arranged, for example, at one end of the shaft and connected to this rotationally. The shaft can be configured, for example, tubular.

For example, the measuring element can be configured in strip or spiral shape. The measuring element can be attached at least in sections to the shaft and, depending on the embodiment, extend along a lateral surface of the shaft or within the shaft.

A survey of people suffering from diabetes has shown that those affected could see significant added value if, for an insulin pen, the last dose of insulin at the appropriate injection time could be continuously recorded. This requires a sensor that detects either the level of the ampoule or the injected dose and either displays directly on the device in a display or transmits to an additional device.

The approach presented here is based on the finding that the integration of a resistive or inductive sensor element in an injection device for injecting a fluid, a dose or a level of the fluid can be reliably and accurately determined. Advantageously, the sensor element can be mechanically coupled to a shaft arranged to be rotatable or displaceable in the injection device for adjusting the dose or actuation of the injection device, so that a length or a number of turns of the sensor element and thus a resistance or an inductance of the sensor element depending on the position of the shaft changes. On the basis of a change in the resistance or the inductance during movement of the shaft can thus be concluded that an injected or remaining dose of the fluid.

For example, the injection device as insulin pen with a dose sensor based on a measuring element in the form of a spring with variable Tap can be realized, the inductance of the spring for detecting the dose can be evaluated. In this case, the spring may for example be rigidly connected to the dose button and arranged such that its number of turns correlates with an angular position of the dose button. Additionally or alternatively, the injection device can be realized with a resistive dose sensor based on a measuring element in the form of a resistance structure, wherein the set dose can be determined by a simple resistance measurement. For example, an optional button can be integrated into the dose button without much additional effort in order to detect the injection that has taken place. Depending on the embodiment, the injection device may comprise a microcontroller for measuring data acquisition or further electronic components for communication with external devices such as smartphones.

By such an injection device user safety can be increased. For example, this can prevent a wrong dosage of insulin amount, so that serious acute or long-term consequences can be avoided.

Furthermore, such an injection device offers the advantage of a reduced administrative burden for a doctor, since a manual protocol management can be omitted. Instead, for example, a dose value automatically detected by the injection device can be electronically documented and sent, for example using a suitable smartphone application.

Last but not least, a dose measurement according to the approach described here can be done with standard electronic components, which can reduce the manufacturing cost of the injection device.

According to one embodiment, the measuring element can be realized as a spiral spring. By means of this embodiment, the injection device can be produced in a particularly cost-effective manner. Furthermore, this allows a simple and accurate measurement of the inductance of the measuring element.

According to a further embodiment, the measuring element may extend at least in sections within the shaft. Additionally or alternatively, the measuring element can be rotationally connected or connectable to the shaft and / or the dose button. As a result, the injection device can be made as compact and robust as possible.

It is advantageous if the shaft has a thread for screwing the shaft to the shaft receiving portion. Thereby, the shaft can be moved by turning the Dosisknopfes within the housing.

Here, the measuring element may at least partially extend along the thread. For example, the measuring element can be introduced into a depression of the thread. As a result, the measuring element can be attached to the shaft with little effort.

According to a further embodiment, the injection device can have at least one contacting element for the electrically conductive contacting of the measuring element to the shaft receiving section and / or the housing stop. The contacting element may, for example, be a sliding contact. As a result, a reliable electrical contacting of the measuring element can be ensured in every position of the shaft.

According to a further embodiment, the dose button may have a dose button port. The Dosisknopfanschluss can be electrically conductively connected to the contacting or connectable. As a result, a measuring signal generated by the measuring element can be tapped off at the dose button.

In an alternative embodiment, the dose button may include the dose button port and the housing having a first housing port and a second housing port. In this case, the dose button connection with the first housing connection and the contacting element with the second housing connection can be electrically conductively connected or connectable. As a result, the measurement signal generated by the measuring element can be tapped at several points of the injection device.

The injection device can also have a return element for acting on the shaft and / or the dose button with a restoring force. In particular, the restoring element can be clamped or clamped between the dose button and the housing stop. For example, the return element can be realized as a spring. Thereby, the operability of the injection device can be improved.

According to a further embodiment, the dose button connection can be electrically conductively connected or connectable via the restoring element to the contacting element or the first housing connection. This makes it possible to dispense with an additional connecting line for connecting the Dosisknopfanschlusses with the contacting element or the first housing connection.

Furthermore, the dose button may have another dose button port. In this case, the further dose button connection can be electrically conductively connected or connectable to an end of the measuring element facing the dose button. As a result, a simple electrical contacting of the measuring element is made possible.

The approach described herein further provides a method for determining a dose of a fluid using an injection device according to any one of the preceding embodiments, the method comprising the steps of:
Reading in a measuring signal representing an impedance of the measuring element; and
Evaluate the measurement signal to determine the dose of fluid.

Another advantage is an embodiment of the approach proposed here, in which the impedance is determined as a measurement signal in the step of reading in using a DC voltage signal or AC voltage signal impressed on the measuring element.

These methods can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit.

The approach presented here also creates a device that is designed to perform the steps of a variant of a method presented here in appropriate facilities to drive or implement. Also by this embodiment of the invention in the form of a device, the object underlying the invention can be solved quickly and efficiently.

For this purpose, the device may comprise at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting data or control signals to the sensor Actuator and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The arithmetic unit may be, for example, a signal processor, a microcontroller or the like, wherein the memory unit may be a flash memory, an EPROM or a magnetic memory unit. The communication interface can be designed to read or output data wirelessly and / or by line, wherein a communication interface that can read or output line-bound data, for example, electrically or optically read this data from a corresponding data transmission line or output to a corresponding data transmission line.

In the present case, a device can be understood as meaning an electrical device which processes sensor signals and outputs control and / or data signals in dependence thereon. The device may have an interface, which may be formed in hardware and / or software. In the case of a hardware-based embodiment, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the device. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules.

Also of advantage is a computer program product or computer program with program code which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially when the program product or program is executed on a computer or a device.

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. It shows:

1 a schematic representation of an injection device according to an embodiment;

2 a schematic representation of a portion of an injection device according to an embodiment;

3 a schematic representation of an injection device according to an embodiment;

4 a schematic representation of an injection device according to an embodiment;

5 a schematic representation of an injection device according to an embodiment;

6 a schematic representation of an injection device according to an embodiment;

7 a schematic representation of an injection device according to an embodiment;

8th a schematic representation of an injection device from 7 ;

9 a schematic representation of an injection device according to an embodiment;

10 a schematic representation of an injection device from 9 ;

11 a schematic representation of a measuring element according to an embodiment;

12 a schematic representation of a measuring element 11 ;

13 a schematic representation of a measuring element 11 ;

14 a schematic representation of a measuring element 11 ;

15 a schematic representation of a device according to an embodiment; and

16 a flowchart of a method according to an embodiment.

In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similar acting, wherein a repeated description of these elements is omitted.

1 shows a schematic representation of an injection device 100 according to an embodiment. Shown is a cross section through the injection device 100 , here an insulin pen. The injection device 100 includes a metering device 102 with a dose button 103 and a shaft 104 , where the dose button 103 at one end of the shaft 104 is appropriate. The shaft 104 is with an optional thread 106 executed, in which an electrically conductive resistance structure as a measuring element 108 is inserted so that the measuring element 108 can work as impedance measuring element. A cylindrical housing 110 of the injection device 100 has a shaft receiving portion 112 for picking up the shaft 104 on. The shank receiving portion 112 is as a counterpart to the thread 106 formed so that the shaft 104 when turning the dose button 103 along a longitudinal axis of the housing 110 is moved. According to this embodiment, on the shaft receiving portion 112 a contacting element 113 , Here a sliding contact in the form of a leaf spring, mounted, which is the electrically conductive contacting of the measuring element 108 serves. Between the dose button 103 and one inside the case 110 located housing stop 114 with an opening 116 is an optional mechanical component 118 arranged. The housing stop 114 in the form of a fixed passage prevents a higher dose can be set, as still fluid in the carpule of the injection device, not shown here 100 located. To the shaft 104 closes a stamp 120 on, passing through the opening 116 in one of the shaft 104 extends away. The Stamp 120 has, for example, direct contact with a stopper of the carpule.

Through the thread 106 it is achieved that the shaft 104 when turning the dose button 103 so shifts that a length of the thread 106 inserted measuring element 108 between the dose button 103 and the shaft receiving portion 112 and thus one between the dose button 103 and the shaft receiving portion 112 measurable resistance of the measuring element 108 changes.

Optional is between the dose button 103 and the housing stop 114 a reset element 122 , here a coil spring, clamped, which is trained to the Dosisknopf 103 or the shaft 104 to apply a restoring force. Here is the return element 122 partly in the shaft 104 introduced.

2 shows a schematic representation of a portion of an injection device 100 according to an embodiment. In the injection device 100 For example, it is a preceding by means of 1 described injection device. Shown is an inventive integration of a Dosismesssystems in an insulin pen as injection device 100 ,

Here the dose button leads 103 when adjusting the dose of the fluid due to the thread 106 in addition to a rotational movement and a translational motion. The measuring element 108 in the form of the resistance structure is in the thread 106 brought in. The measurement of the resistance takes place between the dose button 103 and the shaft receiving portion in the housing 110 , By turning the dose button 103 the ohmic resistance of the measuring element changes 108 which allows a conclusion on the dose.

An electrical resistance can according to R = ρ l / A be calculated. Here ρ denote the resistivity of the resistive material, l the length of the resistor and A its cross-sectional area perpendicular to the current direction. Is an electrically conductive material as a measuring element 108 in the thread 106 introduced, so this can act as an electrical resistance. If the resistance between one side of the Dosisknopf 103 So at the end of the thread 106 , and tapped on the other side on the shaft receiving portion, which is formed as a counterpart of the thread, so the value of the resistance depends on the current position of the Dosisknopfes 103 from. The farther the dose button 103 is rotated, that is, the higher the set dose, the greater the ohmic resistance of the measuring element 108 ,

2 shows by way of example the structure of a designed as a resistance structure measuring element 108 as well as its integration into an insulin pen. In the already existing thread 106 becomes a conductive track in the form of a spiral as a measuring element 108 inserted. The measuring element 108 For example, it is made of stainless steel or a conductive polymer.

For example, for pens of conventional dimensions and a maximum of 60 injectable units, there is a resistance change of about 1.7% per set unit (based on the maximum resistance at 60 units set). This is easily measurable, so that even a resolution of less than one unit can be realized.

For the electrical contacting of the measuring element 108 In the following, several possibilities are described.

3 shows a schematic representation of an injection device 100 according to an embodiment. Shown is a possible electrical contacting within an injection device in the form of a pen. The injection device 100 is essentially the same as based on 1 injection device described, with the difference that the return element 122 additionally as a return conductor for the electrically conductive contacting of the measuring element 108 acts. The housing 110 has a first housing connection 300 and a second housing connection 302 on, with the first housing connection 300 with a housing stop 114 facing the end of the return element 122 electrically connected and the second housing connection 302 with the on the shaft receiving portion 112 located contacting element 113 electrically conductive is connected.

The two housing connections 300 . 302 are from one on the case 110 attached optional additional housing 304 surround. In the additional housing 304 For example, an evaluation for evaluating the of the measuring element 108 arranged measuring signal, wherein the measuring resistor in the form of the measuring element 108 over the two housing connections 300 . 302 connected to the transmitter. For example, the second housing connection 302 via a sliding contact as a contacting element 113 with the measuring element 108 connected while the first housing connection 300 with a spring as a return element 122 electrically conductive is connected. The reset element 122 is via a connection line 306 partially within the dose button 103 runs, with one of the housing stop 114 remote end of the measuring element 108 connected electrically conductive.

4 shows a schematic representation of an injection device 100 according to an embodiment. Shown is another possible electrical contacting of the injection device 100 , In contrast to 3 is the additional housing 304 with the transmitter adjacent one of the shaft 104 opposite side of the Dosisknopfes 103 arranged. Alternatively, the additional housing 304 through the dose button 103 formed, with the transmitter in the dose button 103 is arranged. The dose button 103 further includes a first dose button port 400 and a second dose button port 402 on, which ever in the additional housing 304 end up. Here is the first dose button connection 400 with a dose button 103 facing the end of the measuring element 108 electrically connected while the second Dosisknopfanschluss 402 with a dose button 103 facing the end of the return element 122 electrically conductive is connected. A the case 110 facing the end of the measuring element 108 is about the contacting element 113 with an at least partially within a housing wall of the housing 110 extending housing line 404 connected to the housing stop 114 facing the end of the return element 122 connected. The contacting element 113 forms over the return element 122 a back contact and is via the second Dosisknopfanschluss 402 connected to the transmitter. The first dose button connection 400 is for example directly with the dose button 103 facing the end of the measuring element 108 connected.

All the electronic components for detecting the resistance, calculating the dose of the fluid, and transmitting data are, for example, on a circuit board within the dose button 103 or inside the outside of the injection device 100 arranged additional housing 304 placed. Typically, at least one microcontroller is required to detect the resistance and to calculate the dose. The evaluation electronics Optionally, it may include a device for wirelessly communicating a value representing the dose, such as via Bluetooth or NFC. It is advantageous if, in addition to the dose measurement, activation of the injection device 100 can be discriminated, such as initiating an injection by pressing the Dosisknopfes 103 , For example, an optional button in the dose button 103 be integrated as follows from 5 described.

5 shows a schematic representation of an injection device 100 according to an embodiment. The injection device 100 essentially corresponds to a preceding on the basis of 3 and 4 described injection device. As in 3 is the injection device 100 with the case 110 attached and over the two housing connections 300 . 302 electrically conductive contacted additional housing 304 realized. At the dose button 103 are the two Dosisknopfanschlüsse 400 . 402 , These do not end in the additional housing 304 but with one at the dose button 103 attached optional button 500 connected electrically conductive. The button 500 comprises at least one electrically conductive structure 502 for electrically conductive connection of the two Dosisknopfanschlüsse 400 . 402 in the activated state of the button 500 , The electrically conductive structure 502 is via a spring mechanism 504 with the dose button 103 connected, wherein the electrically conductive structure 502 in the non-activated state of the button 500 spaced apart from the two dose button ports 400 . 402 is arranged so that between the two Dosisknopfanschlüssen 400 . 402 no electrically conductive connection exists. The two dose button connections 400 . 402 For example, by separating an electrical connection line between the measuring element 108 and the return element 122 be generated.

Will the button 500 activated by pressing, ie, an injection is started, then a resistance measurement between the two housing connections 300 . 302 performed to determine the set dose. The button 500 can also be used to activate the transmitter. As soon as the voltage is applied between the housing connections 300 . 302 a measurable current flow is detected, the resistance measurement can be started. As soon as the button 500 is released, for example, a transfer of the dose value to an external device.

6 shows a schematic representation of an injection device 100 according to an embodiment. In contrast to 5 is the return line according to this embodiment using a cable 600 realized instead of the default element, the cable 600 the second dose button port 402 and the first housing connection 300 electrically conductive interconnects. The cable 600 runs at least partially within the shaft 104 ,

The adjustable angle of the dose button 103 For example, it can be limited to three revolutions. In this case, the cable wraps 600 even just three revolutions around the mechanical component 108 which is usually easily possible.

Alternatively or in addition to the wireless transmission, the dose value can also be displayed on a display, such as an e-ink display, which allows a particularly low-energy, permanent display. The display can, for example, on the dose button 103 , on the housing 110 or on the shaft 104 to be appropriate. The dose value should be directly at the injection device 100 should be displayed, so there should be a possibility for time recording. This may for example be part of the microcontroller and be initialized at a first radio contact.

7 shows a schematic representation of an injection device 100 according to an embodiment. This in 7 shown injection device 100 essentially corresponds to a preceding on the basis of 1 to 6 described injection device. Instead of a resistive element, the injection device 100 according to 7 a coil element, here a coil spring, as a measuring element 108 on. The measuring element 108 runs partially within the shaft 104 and is between the dose button 103 and the housing stop 114 clamped. A dose button 103 facing side of the measuring element 108 is non-rotating with the dose button 103 connected. A dose button 103 opposite side of the measuring element 108 is over one at the housing stop 114 attached sliding contact as a contacting element 113 , about a leaf spring, contacted electrically conductive. The housing stop 114 is according to this embodiment with a hole as an opening 116 and another opening 700 realized, wherein the measuring element 108 through the opening 116 and the stamp 120 through the further opening 700 passed through. The two openings 116 . 700 can also be referred to as feedthroughs. The measuring element 108 is designed to twist the dose button 103 through the opening 116 to be threaded through. The shaft 104 is according to 7 with the thread 106 realized, so that when rotating the Dosisknopfes 103 in addition to a number of turns and a length of the measuring element 108 between the dose button 103 and the housing stop 114 changes.

As mentioned, the Dosisknopf leads 103 due to the thread 106 in addition to a rotational movement and a translational motion. The bigger the set angle of rotation, the further the dose button becomes 103 over the thread 106 out of the case 110 unscrewed. The distance between the dose button 103 and housing 110 then corresponds to the path length, for example, the insulin cartridge when pressing the dose button 103 is emptied, optionally scaled with a translation factor. For this presses the stamp 120 on the insulin cartridge. The Stamp 120 is for example arranged at the end of a further threaded rod, which can be rotated via a locking mechanism in one direction only. Through the mechanical component 118 , such as in the form of a driver, will ensure that the dose button 103 can be unscrewed as far as the remaining level in the insulin cartridge is.

Alternatively, the dose button 103 be made rotatable without its distance from the housing 110 to change, as in the following with reference to the 9 and 10 is described. By the rotation, for example, a spring is tensioned whose potential energy through a mechanism during injection into a translational movement of the punch 120 is transferred.

Hereinafter, an embodiment of the injection device 100 again described in other words.

The injection device 100 comprises a sensor arrangement for detecting a currently injected amount of insulin in the form of a spring as a measuring element 108 , An inductance of the measuring element 108 depends on an angular position of the dose button 103 from. The measuring element 108 is on one side rigid with the dose button 103 connected and has on this side on a first electrical contact. On the other side is the measuring element 108 through a passage in the form of the opening 116 threaded there and there electrically via a sliding contact as a contacting element 113 contacted. Now the dose button 103 twisted, the measuring element rotates 108 with and is doing through the opening 116 passing shot. This changes in the case of a dose button, which also performs a translational movement during rotation, both the number of turns and the length of the coil in the form of the measuring element 108 , Performs the dose button 103 when turning, however, no translation movement, so only changes the number of turns.

The inductance value is measured, for example, when the injection is activated, ie when the dose button is pressed, converted into the dose, stored and displayed on an integrated display or transferred to an external device.

berechnet werden kann. Hier bezeichnen μ₀ die magnetische Feldkonstante, μr die magnetische Permeabilitätskonstante, N die Windungszahl, A die Querschnittsfläche und l die Spulenlänge. Ändert sich nun die Windungszahl oder gleichzeitig die Windungszahl sowie die Länge der Spule, so führt dies zu einer Änderung der Induktivität.Is the measuring element 108 , as in 7 shown, realized as a spiral spring, it acts in principle as a coil whose inductance according to

can be calculated. Here μ ₀ denotes the magnetic field constant, μr the magnetic permeability constant, N the number of turns, A the cross-sectional area and l the coil length. If the number of turns or the number of turns and the length of the coil change, this leads to a change in the inductance.

eine Resonanzfrequenz, die von der Induktivität abhängt. Wird beispielsweise ein Kondensator mit einer Kapazität von 500 pF verwendet, so liegt die Resonanzfrequenz im Bereich einiger Megahertz und ist leicht messbar. Eine solche Messung kann mit sehr günstigen Standard-Elektronikkomponenten realisiert werden. If the coil is connected in an electrical resonant circuit, it follows

a resonant frequency that depends on the inductance. For example, if a capacitor with a capacitance of 500 pF is used, the resonance frequency is in the range of a few megahertz and is easily measurable. Such a measurement can be realized with very cheap standard electronic components.

As an alternative to determining the inductance via the measurement of the resonance frequency, the following methods are also conceivable.

When using an L-integrator, a DC voltage is applied to the measuring element 108 applied and the rising current with an operational amplifier converted into a measuring voltage. The measuring voltage allows a conclusion about the inductance.

When using a DC-DC converter, the energy of the measuring element 108 charged to a capacitor whose voltage serves as a measurement signal for determining the dose of the fluid.

Alternatively, a parallel resistor can be determined. In this case, an effective resonance parallel resistance and a resonant frequency of a resonant circuit are determined. By selecting a suitable parallel capacitance, the resonance frequency can be adjusted.

Also conceivable is the use of a reactive voltage divider. In this case, a phase relationship between an excitation sinusoidal signal and a voltage across the LC resonant circuit is determined via a phase locked loop (PLL). Based on the phase then the inductance can be calculated.

The measuring element 108 can be integrated in a bridge circuit. The main task of the hardware here is the demodulation of the measuring signal. For this purpose, at least one additional reference coil should be present.

Analogous to one based on the 1 to 6 described injection device, all electronic components for detecting the inductance, for calculating the dose and for transmitting data on a circuit board within the Dosisknopfes 103 or within an additional housing, the outside of the injection device 100 is located. Typically, at least one capacitor is required to measure the inductance across the resonant frequency of a resonant circuit, a power supply such as a coin cell, and other components requiring at least one microcontroller to measure the resonant frequency and calculate the dose. In addition, the injection device 100 a module for wireless transmission of the dose value, such as via Bluetooth or NFC include.

8th shows a schematic representation of an injection device 100 out 7 at another position of the dose button 103 , In contrast to 7 Here is a lower dose set, with the dose button 103 closer to the housing 110 as in 7 located. Thus, there is also a larger proportion of the measuring element 108 on the from the dose button 103 opposite side of the opening 116 , This is the inductance of the measuring element 108 between the dose button 103 and the contacting element 113 lower.

9 shows a schematic representation of an injection device 100 according to an embodiment. Unlike the 7 and 8th is the shaft 104 according to 9 with a circumferential groove 800 realized instead of a thread. The shank receiving portion 112 is with a survey 802 realized in the groove 800 intervenes. Thus, the shaft performs 104 upon rotation of the dose button 103 only a rotational movement. This causes the rotation of the dose button 103 only the number of turns of the measuring element 108 between the dose button 103 and the housing connection 114 changes.

10 shows a schematic representation of an injection device 100 out 9 , in contrast to 9 is the dose button 103 in 10 in a position in which the measuring element 108 a lower number of turns between dose button 103 and housing connection 114 as in 9 having.

The 9 and 10 show an inventive integration of a dose sensor in an injection device, in which the dose button 103 when turning 103 does not translate. In 9 are the dose button 103 and the measuring element 108 in an initial position. Upon rotation of the dose button 103 becomes the measuring element 108 , as in 10 shown through the opening 116 threaded, resulting in a total length of the measuring element 108 and thus, based on the contacting element 113 , also the number of turns of the measuring element 108 changes. About a measurement of the inductance of the measuring element 108 can now be closed to the dose of the fluid.

11 shows a schematic representation of a measuring element 108 according to an embodiment, such as a measuring element, as described above with reference to 7 to 10 is described. Shown is a principle of a spring contact. Here is the measuring element 108 at a first location x1, for example, an end of the measuring element facing the dose button 108 corresponds, and at a second point x2, where the contacting element 113 the measuring element 108 touched, electrically contacted. It can also be seen that the opening 116 laterally offset to a central axis 1000 of the designed as a spiral spring measuring element 108 is arranged.

The 12 to 14 show schematic representations of a measuring element 108 out 11 in different positions of the dose button. Here is the measuring element 108 at the point x1, at which their first electrical connection is located, rigidly connected to the Dosisknopf. A second electrical connection at the point x2 is realized by a stationary sliding contact as a contacting element. 12 shows the measuring element 108 in a state corresponding to a zero position of the rotary knob. In the example shown, the measuring element 108 a length l1 and a number of turns N = 5. If it is an injection device, in which the dose knob performs a translational movement during rotation, then both the length and the number of turns of the measuring element change as the dose button is rotated 108 , as in 13 shown. If, on the other hand, it is an injection device in which the dose button does not translate during rotation, the length remains constant and only the number of turns changes, as in 14 shown.

15 shows a schematic representation of a device 1400 according to an embodiment. The device 1400 For example, part of a preceding based on the 1 to 14 be described injection device. The device 1400 includes a read-in unit 1410 for reading in a measuring signal generated by the measuring element 1415 in that an impedance of the measuring element, for example, depending on the embodiment, a resistance or an inductance of the measuring element or both, represents. In particular, the measuring element may be designed to change a length of a coil winding and / or an electrical conductor upon actuation of the dose button. This reading can be determined, for example, by using an impedance measurement by means of a DC voltage or AC voltage impressed on the measuring element. To the reading unit 1410 is an evaluation unit 1420 connected, previously also called evaluation, which is designed to the measurement signal 1415 evaluate. As a result of the evaluation of the measuring signal 1415 generates the evaluation unit 1420 a dose value 1425 representing a dose or level of the fluid. The dose value 1425 For example, it may be transmitted wirelessly via an appropriate interface to an external device, such as a display device attached to the injection device.

16 shows a flowchart of a method 1500 according to an embodiment. The procedure 1500 For example, in order to determine a dose of a fluid, it is possible to use a device as described above with reference to FIG 15 is described. This is done in one step 1510 read in the measuring signal generated by the measuring element. In a further step 1520 the measurement signal is evaluated to determine the dose of the fluid.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims (15)

Injection device ( 100 ) for injecting a fluid, wherein the injection device ( 100 ) has the following features: a housing ( 110 ) having a shaft receiving portion ( 112 ) and / or a housing stop ( 114 ) with at least one opening ( 116 ; 700 ) having; a metering device ( 102 ) for metering the fluid, wherein the metering device ( 102 ) a movable in the shaft receiving portion ( 112 ) arranged or arrangeable shaft ( 104 ) and a dose button ( 103 ) for moving the shaft ( 104 ) having; and a measuring element ( 108 ) for determining a dose of the fluid, wherein the measuring element ( 108 ) is formed as an impedance measuring element, in particular wherein the measuring element ( 108 ) is formed to a length of a coil winding and / or an electrical conductor upon actuation of the Dosisknopfs ( 103 ) to change. Injection device ( 100 ) according to claim 1, characterized in that the measuring element ( 108 ) is designed as a resistance element and / or as a coil element, wherein the measuring element ( 108 ) at least in sections between the dose button ( 103 ) and the shaft receiving portion ( 112 ) on the shaft ( 104 ) and is adapted to move when moving the shaft ( 104 ) so that a length of the measuring element ( 108 ) between the dose button ( 103 ) and the shaft receiving portion ( 112 ), and / or wherein the measuring element ( 108 ) at least in sections between the dose button ( 103 ) and the housing stop ( 114 ) and is adapted to move when moving the shaft ( 104 ) through the opening ( 116 ), that a number of turns and / or a length of the measuring element ( 108 ) between the dose button ( 103 ) and the housing stop ( 114 ) changes. Injection device ( 100 ) according to claim 2, characterized in that the measuring element ( 108 ) is realized as a spiral spring. Injection device ( 100 ) according to one of the preceding claims, characterized in that the measuring element ( 108 ) at least in sections within the shaft ( 104 ) and / or rotationally fixed to the shaft ( 104 ) and / or the dose button ( 103 ) is connected or connectable. Injection device ( 100 ) according to one of the preceding claims, characterized in that the shaft ( 104 ) a thread ( 106 ) for screwing the shaft ( 104 ) with the shaft receiving portion ( 112 ) having. Injection device ( 100 ) according to claim 5, characterized in that the measuring element ( 108 ) at least in sections along the thread ( 106 ). Injection device ( 100 ) according to one of the preceding claims, characterized by at least one contacting element ( 113 ) for the electrically conductive contacting of the measuring element ( 108 ) on the shaft receiving portion ( 112 ) and / or the housing stop ( 114 ). Injection device ( 100 ) according to claim 7, characterized in that the dose button ( 103 ) a dose button connection ( 402 ), wherein the dose button connection ( 402 ) electrically conductive with the contacting element ( 113 ) is connected or connectable. Injection device ( 100 ) according to claim 7, characterized in that the dose button ( 103 ) a dose button connection ( 402 ) and the housing ( 110 ) a first housing connection ( 300 ) and a second housing connection ( 302 ), wherein the dose button connection ( 402 ) with the first housing connection ( 300 ) and the contacting element ( 113 ) with the second housing connection ( 302 ) is electrically conductively connected or connectable. Injection device ( 100 ) according to one of the preceding claims, characterized in that the dose button ( 103 ) another Dosisknopfanschluss ( 400 ), wherein the further Dosisknopfanschluss ( 400 ) with a dose button ( 103 ) facing the end of the measuring element ( 108 ) is electrically conductively connected or connectable. Procedure ( 1500 ) for determining a dose of a fluid using an injection device ( 100 ) according to any one of the preceding claims, wherein the method ( 1500 ) includes the following steps: reading in ( 1510 ) an impedance of the measuring element ( 108 ) representing measuring signal ( 1415 ); and evaluation ( 1520 ) of the measuring signal ( 1415 ) to determine the dose of the fluid. Method according to claim 11, characterized in that in step ( 1510 ) of reading in the impedance using a measuring element ( 108 ) impressed DC signal or AC signal as a measurement signal ( 1415 ) is determined. Contraption ( 1400 ) with units ( 1410 . 1420 ), which are adapted to the process ( 1500 ) according to claim 11 or 12 execute and / or to control. Computer program that is adapted to the procedure ( 1500 ) according to claim 11 or 12 execute and / or to control. A machine readable storage medium storing the computer program of claim 14.

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