CH701669A1 - Pressure sensing in a medical delivery device. - Google Patents

Abstract

There is disclosed an apparatus and method for pressure sensing in a fluid-conducting area (121) of an administering device. The device comprises one or more parallel detection capillaries (131) having a first, open end and a second, closed end. The detection capillaries are filled with a compressible gas, e.g. Air, filled and connected at its first end to the liquid-conducting area. A translucent optical element (200) delimits the detection capillaries along the longitudinal direction to at least one side, forming at least one interface. Light is coupled into the optical element in such a way that the light at the boundary surface undergoes a reflection (in particular a total reflection) when there is air at the boundary surface. On the other hand, if there is liquid at the interface that has been pressed into the detection capillaries due to an increased pressure, a reduced reflection (in particular no total reflection) will take place. The reflected light is detected. As a result, a pressure detection is possible, which generates only a very small Staubolus. The pressure detection device can be accommodated in an adapter for connecting an infusion set.

Description

TECHNICAL AREA

The present invention relates to a device for pressure detection in a liquid-carrying area of a processing device. In particular, the processing device can be a medical delivery device, e.g. an infusion device, which is used to administer a liquid drug to a patient.

STATE OF THE ART

Various diseases may require a patient to be given a drug in liquid form, e.g. Taking an insulin supplement or a blood-thinning drug such as heparin for a long time. For this purpose, compact, portable administration devices external to the body are known, which are constantly carried by the patient close to the body.

For a reliable supply of the patient with the drug, it is essential that malfunctions that can lead to an undersupply of the drug or a complete interruption of the administration of the drug, are effectively and safely detected and trigger an alarm and / or cause the device to switch off. Such a malfunction can arise in particular that a blockage (occlusion) of a fluid-carrying line, e.g. of the infusion set, or that the infusion set is kinked so that the medication can no longer flow through the infusion set.

In WO 2008/106810 a modular administration device is specified which has a reusable base unit (reusable part) and a disposable cartridge (disposable part). The base unit contains a drive unit with an electric motor, a gear and a driver as well as the relatively expensive and complex components for operating and controlling the device. The cartridge contains a cartridge with the product and a hydraulic system. When the drive unit is activated, this causes a plug of the hydraulic system to be advanced so that the hydraulic fluid is displaced from a hydraulic reservoir into a displacement reservoir which is adjacent to the carpule plug. This in turn has the effect that the plug of the carpule is advanced and the product is expelled. An occlusion manifests itself in a sharply increasing pressure in the hydraulic system. In order to detect occlusions, the hydraulic system has a blind channel in which a spring-loaded slide is guided. If a threshold pressure in the hydraulic system is exceeded, the slide is moved against the spring force. However, this device for recording pressure is relatively complex and therefore expensive to manufacture. In addition, with this device, occlusions are only recorded indirectly, via an increase in pressure in the hydraulic reservoir.

[0005] EP 1 818 664 discloses an infusion device with an infusion set, in the fluid path of which a deformable membrane is arranged. If the pressure in the liquid path increases, the membrane deforms. This deformation is detected optically without contact, in that light is radiated onto the membrane and, depending on its degree of deformation, is reflected by the membrane in different directions or is absorbed by the membrane to a different extent. Before the infusion set is installed, the membrane is accessible from the outside without protection and can therefore be easily damaged. The device for detecting occlusion is also relatively difficult to calibrate.

US 2008/0 294 094 discloses a device for occlusion detection, in which a deformable membrane is also arranged in the fluid path. A light-permeable optical element is arranged at a distance from the membrane. There is an area filled with air between the membrane and the optical element. A light source sends a beam of light into the optical element. The light hits the interface between the optical element and the air-filled area at an angle that is selected so that the light beam is totally reflected at the transition from the optical element to the air. The reflected light is captured by a light sensor. When the pressure in the liquid path increases, the membrane deforms and touches the interface with the optical element. As a result, there is no longer any total reflection at the interface, and the light enters the membrane with light refraction instead of being reflected. This noticeably decreases the amount of light received by the light sensor.

However, the amount of liquid medicament that is required to deform the membrane sufficiently, is relatively large. In the case of an only temporary occlusion, this leads to a considerable dust colus, which is administered to the patient in an uncontrolled manner after the occlusion has been removed. In particular when the liquid medicament is an insulin preparation, the uncontrolled release of this undesirable amount of dust bolus can have undesirable consequences, including dangerous hypoglycaemia in the patient.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to provide a device for pressure detection in which the formation of a dust colus is reduced and which is nevertheless of simple construction and enables reliable occlusion detection. This object is achieved by a device with the features of claim 1. Further embodiments are given in the dependent claims.

[0009] A device for pressure detection in an area of an administration device carrying a liquid is thus specified, which has: at least one detection capillary with a first, open end and a second, at least indirectly closed end, the detection capillary being filled with a compressible gas at least in an area adjoining the second end and being connected at its first end to the area carrying the liquid; a translucent optical element that directly delimits the detection capillary on at least one side, forming at least one interface, wherein the optical element has a light coupling region in order to couple incident light into the optical element and guide it onto the interface at such an angle of incidence that the light at the interface experiences a higher internal reflection when the gas is located at the interface than when the liquid is at the interface, and wherein the optical element has a light outcoupling region in order to couple out internally reflected light from the optical element at the interface.

The liquid-carrying area is preferably an area which is arranged downstream of the outlet of the product reservoir of the administration device and preferably directly adjoins this outlet, in particular a fluid channel in an adapter that is used to connect an infusion set, or a tube of the actual infusion sets. The liquid, the pressure of which is detected, is then a liquid medicament to be administered. However, the invention is not restricted to this and is suitable for pressure detection in any liquid-carrying area of an administration device, e.g. also for pressure measurement in a hydraulic reservoir with hydraulic power transmission in the administration device.

A capillary is a straight or curved channel that defines a longitudinal direction in the channel direction and whose lateral dimensions transverse to the longitudinal direction are so small that gas and liquid do not mix at the contact surface between liquid and gas, as the surface forces prevent dripping or blistering. Depending on the liquid, this is usually the case when the lateral dimensions of the channel transversely to the longitudinal direction are in the range of at most a few tenths of a millimeter. The channel therefore preferably has lateral dimensions of at most 1 millimeter, preferably of at most 0.5 millimeter, everywhere. Such a channel can also be referred to as a microchannel. A capillary can also be recognized by the fact that the liquid in the channel shows a noticeable capillarity. Capillarity means in particular that a liquid wetting the channel wall increases noticeably in the channel, or a non-wetting liquid shows a noticeable capillary depression. There is a defined boundary in a capillary between gas and liquid. The contact area at this border is very small. The small contact area and the slow diffusion along a capillary also effectively prevent significant amounts of the gas from dissolving in the liquid, provided that such solubility is given to any significant extent.

The detection capillary is at least indirectly closed at its second end. An at least indirectly closed second end is to be understood as meaning that the second end is either formed directly by an end wall of the capillary or that the second end adjoins a space closed off from the environment. In particular, the liquid is not administered through the detection capillary, but the detection capillary is part of a blind channel.

The detection capillary is filled with a gas at least in one area that adjoins the at least indirectly closed second (hereinafter also referred to as the distal end) end of the detection capillary. The entire detection capillary is preferably filled with the gas during normal operation. The gas can be an inert gas such as nitrogen or argon. However, the gas is preferably air. A possible oxidation effect of the oxygen in the air on the liquid is largely minimized by the small contact area. This gas forms a gas column in the detection capillary, which is compressed as soon as liquid is pressed from the liquid-carrying area into the open end of the detection capillary. The gas column forms a gas spring and exerts a counterforce on the liquid column. In the steady state, the pressure force and the counterforce are in equilibrium. The length of the liquid column in the detection capillary is therefore a direct measure of the pressure of the liquid in the area carrying the liquid.

The presence and / or the length of the liquid column in the detection capillary is detected optically. For this purpose, there is a transparent optical element which delimits the detection capillary at least partially along the longitudinal direction defined by the capillary. The optical element is preferably connected to a carrier so that the detection capillary is delimited jointly by the optical element and the carrier. The carrier is preferably poorly reflective and preferably light-absorbing. A groove can be formed in at least one of the parts (optical element and / or carrier), which together with the other part delimits the detection capillary. The optical element is designed so that incident light can be guided at a certain angle onto the interface between the optical element and the detection capillary. If the gas is the medium at the interface between the optical element and the detection capillary, there is a stronger internal reflection at the interface than if the liquid is at the interface. The internal reflection at the interface is preferably carried out by total reflection, provided that the gas is located at the interface. If, on the other hand, the liquid is located at the interface, there is preferably no longer any total reflection, and the incident light enters the liquid predominantly with refraction at the interface. In order for total reflection to take place, the angle of incidence of the incident light relative to the normal device on the interface must be greater than the critical angle θc of total reflection,

where n2 is the refractive index of the medium (here the gas) in the detection capillary and where n1 is the refractive index of the material of which the optical element is made in the area of the interface.

The light used can be visible light, but also light in the infrared or ultraviolet range. In more general terms, the light is electromagnetic radiation which, in the area of the dimensions of the device, can be described essentially according to the laws of ray optics. The optical element is accordingly in at least one corresponding wavelength range of the electromagnetic spectrum, e.g. in the IR, visible or UV range, permeable, but can be non-transparent (opaque) in other areas.

The optical element preferably consists of a drug-compatible, i.e. an insulin-compatible material when used with insulin, e.g. PCTG (glycol modified polycyclohexanedimethylene terephthalate) or PC (polycarbonate). Such materials typically have an index of refraction in the range of 1.50 to 1.60. The critical angle of total reflection for the medium air (refractive index almost 1.00) or for other gases in the detection capillary is thus typically around 38-42 °. In particular, a total reflection will therefore generally take place at an angle of incidence of at least 45 ° to the surface normal. If, on the other hand, the liquid is at the interface (refractive index typically 1.30-1.35), the critical angle is significantly larger (typically greater than 55 °) and total reflection no longer takes place. Instead, a significant part of the incident light enters the liquid with refraction at the interface. The amount of light reflected is thus considerably reduced. This enables a very efficient and reliable determination of whether the gas or the liquid is in the detection capillary.

Due to the small lateral dimensions of the detection capillary, the volume of liquid that enters the pressure detection device when the pressure rises is very small. This results in a very low dust bolus. This enables occlusion to be detected very quickly, since the pressure detection device is hardly "flexible" (ie it only takes up very little volume that could lead to a pressure reduction) and, therefore, with a conventional administration device operated incrementally in individual administration cycles, a considerable increase in pressure results after just a few administration cycles . The proposed pressure detection device also enables quantitative pressure measurement by measuring the length of the liquid column in the detection capillary. Overall, the proposed pressure detection device is very simple and inexpensive. Since it does not require any moving parts, it is very safe to operate.

At its open end, the detection capillary is preferably connected to a connecting channel which connects the detection capillary to the fluid-carrying area. As a result, the detection capillary does not have to be connected directly to the liquid-carrying area to be monitored, but can be arranged in such a way that particularly simple and reliable detection is possible. The connecting channel can run at an angle, in particular essentially perpendicular to the longitudinal direction of the capillary. It preferably forms a capillary itself. Before the device is started up for the first time, both the detection capillary and the connecting channel are preferably filled with gas. In operation, the connecting channel is preferably at most partially filled with liquid at its end adjacent to the liquid-conveying area, a certain liquid level being possibly unavoidable due to the capillary forces. The liquid then only reaches the detection capillary when a threshold pressure is exceeded.

In a structurally elegant embodiment, the connecting channel is at least partially limited by the optical element, in particular by a preferably angled to the longitudinal direction of the capillary extending feed area of the optical element, which is connected to a carrier for the optical element and is preferably in a bore of the carrier extends into it. In this case, a groove can be formed in at least one of the parts (feed area of the optical element and / or carrier) which, together with the other part, delimits the connecting channel. In an advantageous embodiment, the feed area of the optical element has a cylindrical shape, and in this area a groove is formed which partially delimits the connecting channel. The feed area can then have a through-hole extending transversely to the groove which delimits a part of the liquid-carrying area, the pressure of which is to be monitored.

In certain embodiments there is a carrier for the optical element. A groove (running along the longitudinal direction of the capillary) is formed in this. The optical element then preferably has a flat underside which delimits the groove along its longitudinal direction, and the groove delimited by the optical element forms the detection capillary.

The light coupling area then preferably has a (flat or curved) light coupling surface that is inclined to the flat bottom, and the light coupling area has a light coupling surface that extends symmetrically to the light coupling surface with respect to a plane of symmetry perpendicular to the flat bottom and containing the longitudinal direction . The reflected light is detected symmetrically to the incident light. In particular, the light coupling-in surface and the light coupling-out surface can be inclined, at least in some areas, at an angle to the flat underside that is greater than the critical angle of total reflection at the interface when the gas is at the interface, and that is smaller than the critical angle of total reflection when the fluid is at the interface. The light coupling-in surface and / or the light coupling-out surface can also be curved in order to achieve a focusing effect on the interface.

In these embodiments, a single detection capillary can be present, or several such capillaries can be arranged parallel to one another.

In other embodiments, a carrier for the optical element is also present. The optical element then has an underside which is attached to the carrier (110) in a sealing manner, forming at least one first detection capillary and a second detection capillary running parallel to the first detection capillary. Of course, three or more such detection capillaries can also be present. Each of the detection capillaries has a first, open end and a second, at least indirectly closed end. Each of the detection capillaries is filled with the compressible gas at least in an area adjoining the second end and connected at its first end to the liquid-carrying area. The optical element has at least a first and a second groove on its underside. The first detection capillary is partially delimited by the first groove along a longitudinal direction, and the second detection capillary is partially delimited by the second groove along the longitudinal direction. The first groove has at least one first interface, extending along the longitudinal direction, between the optical element and the first detection capillary, and the second groove has a second interface, extending along the longitudinal direction, between the optical element and the second detection capillary. The first and second interfaces are arranged at an angle to each other with respect to a direction perpendicular to the longitudinal direction such that light that reaches the first interface of the first groove and is internally reflected by this from the light coupling area of the optical element, onto the second interface of the second Groove can get in order to be reflected from there to the light extraction area.

In these embodiments, two internal reflections take place, which increases the light-dark contrast between gas and liquid. In addition, this embodiment enables the illumination and the detection to take place from the same side (so that the light coupling area and the light decoupling area can coincide). For this purpose, the first and the second interface are arranged to one another in such a way that they form an angle of 90 ° to one another. Light that strikes the first interface along a direction of incidence (preferably at an angle of incidence of approx. 45 ° to the surface normal of the first interface) and is reflected by this onto the second interface, is then reflected by the second interface against the direction of incidence. The angle between the boundary surfaces can, however, also deviate from 90 ° and in particular be greater than 90 ° if illumination and detection are to take place from different directions.

In an advantageous embodiment, the detection capillaries are connected at their second end to a common pressure compensation space that is closed off from the environment. As a result, pressure equalization takes place in the gas between the detection capillaries, and the pressure prevailing in the capillaries is the same from capillary to capillary. In addition, a suitable choice of the volume of the pressure equalization space makes it possible to vary the “spring constant” of the gas spring, which is formed by the gas. The larger the volume of the pressure equalization space, the smaller the pressure increase that is required to allow the liquid column in the detection capillaries to rise by a certain amount. The sensitivity of the pressure detection device can thus be adjusted. For this reason, a pressure equalization space at the second end can be advantageous even if only a single detection capillary is present. The pressure equalization space is an example of an embodiment in which the capillaries are indirectly closed.

At their open, first end, the detection capillaries can be connected to a common distribution space for supplying the liquid to the detection capillaries, the distribution space then being connected to the liquid-carrying area via a connecting channel. This means that only a single connection channel is required.

In a specific embodiment, the optical element has a plurality of parallel grooves on its underside which delimit a plurality of parallel detection capillaries. Each of the grooves has a first and a second flat flank, each of which runs along the longitudinal direction. The flanks enclose an angle of at least 90 °. The first flank of one of the grooves forms the first interface, and the second edge of an adjacent groove forms the second interface. In particular, the grooves can be V-shaped. In this embodiment, the carrier can have a flat upper side.

The device can also be provided with a light source and a light sensor in order to automatically detect the presence of liquid or gas in the detection capillary. For this purpose, a control device with a light source to couple light into the light coupling area of the optical element and with a light sensor to couple light internally reflected in the optical element at the interface in the light coupling area from the optical element can be provided. The control device is then designed to detect a measure for the amount of internally reflected light. The control device can be arranged in a different part of the administration device than the detection capillary with the optical element. Thus, the detection capillary with the optical element can e.g. are in a disposable part, in particular an adapter for connecting an infusion set or a cartridge with a drug reservoir, while the control device is in a reusable base unit.

The present invention also relates to an administration device for administering a liquid medicament which is provided with a pressure detection device of the type proposed. Such an administration device can in particular have: a product container for the liquid medicament, having an outlet; drive means for ejecting the liquid medicament under pressure from the container through the outlet; such as a pressure detection device of the proposed type, wherein the open end of the detection capillary is in communication with the outlet of the container, and wherein the control device is designed to determine a pressure increase in the liquid medicament based on the amount of light received by the light sensor and in the event of a pressure increase above a threshold value give an alarm signal.

Such an administration device can in particular be of modular design so that it comprises: a reusable base unit comprising the drive device and the control device with the light source and the light sensor; a replaceable cartridge which comprises the product container for the liquid medicament and which is connectable to the base unit in order to expel the liquid medicament from the product container; and an adapter which can be connected to the cartridge in order to connect an infusion set to the cartridge, and which comprises a liquid line in order to conduct the liquid medicament from the outlet of the product container to the infusion set, the at least one detection capillary being formed on the adapter and on its open one End is connected directly or indirectly to the liquid line.

The invention also relates to an adapter for connecting an infusion set to an administration device, which has: an attachment area for attaching the adapter to the administration device; a connection area for connecting the infusion set to the adapter; a liquid line extending from the attachment area to the connection area; such as a pressure detection device of the type described above, the at least one detection capillary of which is connected at its open end to the liquid line.

[0032] Finally, the invention also relates to a method for pressure detection in a liquid-carrying area of an administration device, which comprises the following steps: Providing a detection capillary with a first, open end and a second, at least indirectly closed end, the detection capillary being filled with a compressible gas at least in an area adjoining the second end and being connected at its first end to the liquid-carrying area, and wherein the detection capillary is delimited along the longitudinal direction to at least one side with the formation of at least one boundary surface by a light-permeable optical element, guiding incident light onto the boundary surface so that the light incident through the light coupling region hits the boundary surface at an angle the light at the interface experiences a higher internal reflection when the gas is located in the area of the interface than when the liquid is located in the area of the interface; Detecting light reflected at the interface; and Determination of a measure for the pressure in the liquid-carrying area based on the amount of light detected at the interface.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the drawings, which are only used for explanation and are not to be interpreted restrictively. The drawings show: FIG. 1 a perspective view of an adapter for connecting an infusion set to a medical administration device; FIG. 2 <sep> a cross section through the adapter in plane A of FIG. 1; 3 shows a longitudinal section through the adapter of FIG. 1 in plane B-B of FIG. 4 shows an enlarged detail from FIG. 3 in area D; 5 shows a longitudinal section through the adapter of FIG. 1 in plane C-C of FIG. 6 shows an enlarged detail from FIG. 5 in area E; 7 shows a perspective view of the adapter of FIG. 1 with the optical element removed; FIG. 8 <sep> a plan view of the adapter with the optical element removed; FIG. 9 shows an enlarged perspective view of the optical element of the adapter of FIG. 1; FIG. 10 <sep> a front view of the optical element from FIG. 9; FIG. 11 shows an adapter according to a second embodiment; FIG. 12 <sep> a front view of the adapter of FIG. 11; 13 shows a longitudinal section through the adapter of FIG. 11 in the plane F-F of FIG. 10; FIG. 14 shows a cross-section through the adapter of FIG. 11 in the plane G-G of FIG. 13; FIG. 15 <sep> an enlarged detail from FIG. 14 in area H; FIG. FIG. 16 <sep> an enlarged perspective view of the optical element of the adapter of FIG. 11; FIG. FIG. 17 <sep> a functional sketch for the operation of the pressure detection device of the adapter of FIG. 11; FIG. FIG. 18 <sep> a sketch to illustrate the light reflection and refraction on the optical element of FIG. 16; and FIG. 19 <sep> a central longitudinal section through the optical element of FIG. 16.

DESCRIPTION OF PREFERRED EMBODIMENTS

First embodiment

In FIGS. 1 to 10, a first embodiment of a pressure detection device according to the invention is illustrated. The pressure detection device is implemented in an adapter 100 which is used to connect an infusion set (not shown) to an administration device (also not shown), in particular an infusion device for subcutaneous administration of a liquid medicament such as e.g. an insulin preparation to connect. The delivery device can e.g. basically be constructed similarly to the administration device specified in WO 2008/106 810. With regard to the possible configurations of an administration device, reference is made to the disclosure of this document.

The adapter 100 has a base body 110 on which a connection area 111 for an infusion set is formed. In the present example, the connection area has the shape of a Luer cone which is surrounded by an annular space 112 for introducing the connection piece of the infusion set. At the opposite end, the adapter 110 has a centrally arranged hollow needle 120 which is held in a needle holder 118 and which is radially surrounded by a tubular needle guard 113. An annular space 114 for connecting the adapter to a cartridge of an administration device follows in the radial outward direction. The annular space 114 is in turn surrounded radially by an outer wall 115. The hollow needle 120 is in fluid communication with the connection area 111 via a fluid channel 121. Guide edges 116 and a guide web 117 serve to guide the adapter on a base unit (not shown) of the infusion device and for the exact placement of an optical element 200, which is described in more detail below, relative to a light source and a light sensor in the base unit.

In an outer area of the base body 110, a cuboid recess is formed which forms a detection area 130 for receiving a pressure detection device. A radial bore 132 extends from the detection area 130 down to the liquid channel 121. This bore 132 can be seen particularly well in FIGS. 7 and 8. A flat groove 131 into which the radial bore 132 opens is formed on the base of the detection area.

In the detection area 130, the optical element 200 is inserted from above, which is shown alone in FIGS. 9 and 10 (a). The optical element 200 comprises a prism-shaped main section 210, from the flat underside 211 of which a cylindrical feed section 220 extends downward. The main section has a planar light coupling surface 212 and a planar light decoupling surface 213. These surfaces run inclined to the surface normal of the underside 211 and each enclose an angle of approximately 45 ° with this surface normal. The inclined surfaces 212, 213 end at a flat upper side 214, which runs parallel to the lower side 211. At the bottom, each of the surfaces 212, 213 is adjoined by a perpendicular side surface 215. Overall, the main section 210 of the optical element 200 thus has the shape of a straight prism with an irregularly hexagonal base. The base has the shape of an isosceles, right-angled triangle, the hypotenuse of which delimits the underside of the main section, the tip of which is cut off by a cut parallel to the underside, and whose cathets are cut off by cuts perpendicular to the underside.

From the flat underside 211 of the main section, the feed section 220 extends downward. Its diameter is smaller than the width of the lower side 211. A feed groove 221 is formed parallel to the axis of the feed section 220. Near the lower end of the feed section 220, this opens into a through-bore 222 which runs parallel to the longitudinal direction of the main section 210 and perpendicular to the feed groove 221.

When the optical element is inserted from above into the detection area 130 of the base body 110, the flat underside 211 of the main section 210 rests on the base of the detection area 130. The feed section extends through the bore 132 down to the liquid channel 121. The through-bore 222 is aligned with the liquid channel 121 and the hollow needle 120 so that there is a continuous fluid connection from the hollow needle 120 to the fastening area 111. The feed section sits tightly in the bore 132. As a result, the feed groove 221 together with the wall of the bore 132 forms a feed channel which connects the liquid channel 121 with the longitudinal groove 131 in the base area of the detection region 130. Due to its small diameter, the feed channel forms a capillary. Outside the groove 131, the underside 311 of the main section 210 rests directly on the base of the detection area 130 and is here, e.g. by laser welding, sealingly connected to the base. The groove 131 is thereby closed at the top by the optical element 200. Together with the optical element, the groove 131 forms a detection capillary.

The pressure detecting device is operated as follows. In the normal operating state, the detection capillary and at least one part of the supply channel adjoining it are filled with air. From a light source 410, which is only indicated schematically in FIGS. 2 and 10, incident light 411 (FIG. 10) is coupled into the optical element 200 through the light coupling surface 212. This light strikes the interface between the optical element 200 and the detection capillary at an angle of incidence of approximately 45 ° to the surface normal. This angle is larger than the critical angle of total reflection in relation to air. The light striking the interface is therefore totally reflected at the interface and exits the optical element 200 again as reflected light 421 (FIG. 10) at the light coupling-out surface. Here it can be detected by a light sensor 420 which is again only indicated schematically in FIGS. 2 and 10.

If the pressure in the liquid channel 121 rises because of an occlusion in the infusion set, the liquid in the liquid channel is pressed upwards in the direction of the detection capillary through the capillary formed by the feed groove 221. The liquid compresses the air in the detection capillary. The air is compressed until the forces due to the air pressure are in equilibrium with the forces due to the liquid pressure in the liquid channel 121. The length of the liquid column in the detection capillary is thus a direct measure of the pressure that prevails in the liquid channel 121.

When sufficient liquid has entered the detection capillary, the incident light 411 hits an interface between the optical element 200 and the liquid. The refractive indices of the optical element and the liquid differ less than the refractive indices between the optical element and air. In particular, the critical angle of total reflection between the optical element and the liquid is now greater than the angle of incidence of the light 411 relative to the surface normal, so that total reflection no longer takes place at the interface. The light is therefore only reflected to a small extent and instead is largely refracted into the liquid, as is indicated by the arrow 412. Here the light is partially absorbed directly. The non-absorbed part of the light hits the base body and is absorbed there, possibly after one or more reflections. If the base body 110 is made of a transparent material, it is also conceivable that at least part of the light emerges from the base body 110.

Thus, a considerable amount of less reflected light 421 reaches the light sensor 420. The length of the liquid column in the detection capillary can therefore be deduced from the amount of reflected light. If the amount of reflected light falls below a certain threshold value, this indicates that a threshold pressure in the fluid channel 121 has been exceeded, which in turn indicates an occlusion in the infusion set.

A light-emitting diode, e.g. in the infrared range. A suitable light sensor is e.g. a photodiode or a phototransistor which forms part of a sensor circuit in a manner known per se.

The present pressure detection device basically not only enables the determination that a predetermined threshold value of the pressure has been exceeded, but also fundamentally enables a quantitative determination of the pressure. For this purpose, the light source can be designed so that it does not only connect the optical element 200 to one Place illuminated along the longitudinal direction of the optical element, but over a certain area of its length or even over the entire length of the optical element. The light sensor can be designed to quantitatively detect the amount of light reflected, e.g. by emitting a signal, the strength of which depends on the amount of light received, or by being designed as a line sensor with several sensor fields along the length of the optical element.

The administration of a liquid medicament by an administration device of the type mentioned here does not usually take place continuously, but rather incrementally in administration cycles at intervals of a few minutes. With each administration process, only a relatively small amount of the liquid medicament is expelled. Accordingly, the pressure detection device proposed here does not need to be operated continuously, but can be activated in a targeted manner at certain times of an administration cycle in order to determine the pressure conditions at these times. In this way, considerably less electrical energy is required for the pressure detection device than with continuous operation.

Second embodiment

A second embodiment of a pressure sensing device according to the present invention is illustrated in FIGS. 11-19. Again, the pressure detection device is designed in an adapter 100 'which is basically constructed very similar to the adapter 100 of the first embodiment. In this regard, reference is made to the description of the first embodiment above. The same parts are denoted by the same reference numerals as for the first embodiment. Differences to the first embodiment exist in particular in the design of the detection area in the adapter 100 'and in the design of the optical element 200'.

In contrast to the first embodiment, in the second embodiment the base surface of the detection region of the base body 110 is flat and does not have a groove. The optical element 200 'is generally cuboid in shape and is flat on its upper side. On its underside, the optical element 200 'has a plurality of V-shaped grooves 231 running parallel along its longitudinal direction (in the present example nine parallel grooves), the cross section of which has the shape of an equilateral, right-angled triangle. These grooves can be seen particularly well in FIG. At their proximal end, the grooves end in a common distribution space 232 which communicates with the central fluid channel 121 of the adapter via a vertically extending bore 132. In order to reduce the cross section of the bore 132 to the diameter of a capillary, a cylindrical insert (not shown here) can be inserted into the bore 132, which is constructed exactly like the feed section 220 of the optical element 200 according to the first embodiment. At their distal end opposite the distributor space 232, the grooves 231 are connected to a pressure equalization space 233 which extends upward into the optical element.

The optical element 200 'is connected with its underside 230 to the base of the detection area of the base body 110, e.g. by laser welding. The grooves 231 together with the base area form a plurality of detection capillaries running parallel to one another. At their proximal end, these capillaries are connected to the central fluid channel 121 of the adapter 100 'via the distributor space 232 and the supply channel described above. At their distal end, the detection capillaries are connected to the pressure equalization space 233 and are thereby indirectly closed.

During normal operation of the administration device, the detection capillaries are completely filled with air in this embodiment as well. The distribution space 232 and at least a part of the supply duct are also filled with air. In the event of a pressure increase in the central liquid channel 121, liquid again rises through the supply channel. If the pressure exceeds a certain threshold, the liquid reaches the distributor space 232 and from there it passes into the detection capillaries. Once again, the liquid compresses the air previously located in the detection capillaries and in the pressure equalization space 233. The compressive force that the compressed air opposes the liquid at a certain liquid level can be adjusted by the volumes of the pressure equalization space 233 and the distribution space 232. The operating range of the pressure detection device can therefore be adjusted by changing these volumes.

The detection of the liquid columns present in the detection capillaries also takes place in this exemplary embodiment by optical means. The incident light is coupled in through the flat upper side 236 of the optical element 200 'and the reflected light is coupled out again in the opposite direction from this upper side. This is illustrated in FIG. 17 and is shown in more detail in FIG. Each of the grooves 231 has a first flat flank 234 and a second flat flank 235. Incident light 431 which strikes the first flank 234 of a specific groove is reflected by the boundary surface formed on this flank by total reflection in the direction 432, provided that there is air at this boundary surface. The reflected light 432 hits the second flank of the adjacent groove and is reflected again there, provided that there is again air there. The twice reflected light 441 is antiparallel to the incident light and is received by the light sensor 440. If, however, there is liquid rather than air at the interfaces, the incident light is refracted into the liquid, as indicated schematically by arrow 433, and only a small part of the incident light is reflected in direction 432. Most of the remaining reflected light is refracted into the liquid again at the next interface (indicated by arrow 442), and only a very small, unavoidable remainder is reflected as reflected light 441 to the detector 440.

In order to achieve the greatest possible sensitivity, the light source 430 preferably extends over the entire width of the arrangement of detection capillaries, and the light sensor 440 also preferably has a corresponding width. This is only indicated schematically in FIG. Such a “light curtain” can be generated for the incident light by suitable lens arrangements from one or more point light sources, as is known per se from the prior art. It is also known per se from the prior art to focus a reflected light curtain back onto one or more points.

Again, it is advantageous if the light source is designed to illuminate the detection capillaries over their entire length or at least over a certain part of their length, and if the light sensor is designed to quantitatively detect the amount of light reflected. For this purpose, the light sensor can in turn be designed as a line sensor along the longitudinal direction of the detection capillaries or even as a two-dimensional array sensor. Such sensors are known from the field of digital cameras and are available at low cost.

FIG. 17 also illustrates how the light source 430 and the light sensor 440 interact with a control device 300. The control device controls a drive motor 301, which acts on a medicament reservoir 302 in such a way that a liquid medicament is dispensed from the reservoir 302 by activation of the drive motor. The pressure at the outlet of the reservoir 302 is, as is only indicated schematically in FIG. 17 by the line 303, detected by a pressure detection device of the type described here. The motor is activated at regular intervals (administration cycles) for a relatively short time. At certain times in each administration cycle, the light source 430 and the light sensor 440 are activated in order to sense the pressure at the outlet of the reservoir 302. If the amount of light detected by the light sensor falls below a threshold value or other predetermined conditions for the amount of light are met (e.g. the amount of light has decreased by a certain difference to the amount of light in the previous cycle or a certain amount of light has fallen below a certain threshold value several times), the control device generates an alarm signal. On the basis of the alarm signal, the control device can emit an acoustic alarm via an acoustic signal transmitter 304 (e.g. a buzzer), an optical alarm via an optical signal transmitter 305 (e.g. an LED), or a tactile alarm, or the control device can stop the motor 301.

The control device 300 with the motor 301, the signal transmitters 304, 305, the light source 430 and the light sensor 440 can be accommodated in a reusable base unit 310, while the drug reservoir 302 is in a disposable cartridge 320 and the optical element with the Detection capillaries can be located in an adapter that can be detachably attached thereto.

Modifications

While the invention has been described above on the basis of exemplary embodiments, a large number of modifications of the pressure detection device according to the invention are of course possible. Referring to the first embodiment, e.g. another shape of the optical element is possible. In particular, the light coupling-in surfaces and the light coupling-out surfaces of the optical element 200 can be curved instead of flat. In particular, a semi-circular or semi-electric cross-section is possible, as is illustrated schematically in part (b) of FIG. 10. The optical element of the first embodiment can also consist solely of the prismatic main section 210, and the feed section 220 can be designed as a separate component. In the first embodiment it is also not absolutely necessary for the detection capillary to be formed by a groove in the base body 110. A corresponding groove can also be formed in a suitable insert part for the base body, or the detection capillary can be delimited by a groove in the optical element. In order to allow the light to fall in from above instead of obliquely from the side in the first embodiment, the detection capillary can also have a different cross-sectional shape than the rectangular cross-sectional shape described here. In particular, a prism-shaped area can protrude into the cross section of the detection capillary from above, on whose inclined lateral flanks a boundary surface to the interior of the detection capillary is formed. Such a shape is illustrated in part (c) of FIG.

A number of modifications are also possible in the second embodiment. The grooves 231 do not necessarily have to be triangular in cross section as long as they have two flanks which are inclined to one another. The angle enclosed by these flanks is preferably 90 °, as in the present exemplary embodiment, but can also be greater than 90 ° if it is desired that the entering and the reflected light run in different directions in the optical element. Correspondingly, the optical element can in this case be provided with obliquely running light coupling surfaces and light coupling out surfaces on its upper side. The pressure equalization space 233 can optionally be omitted so that the detection capillaries are directly closed at their distal ends. Conversely, in the first embodiment, a pressure equalization space can also be provided at the end of the single detection capillary, as in the second embodiment. A large number of other modifications are possible.

REFERENCE LIST

100, 100 ́ <sep> adapter 110 <sep> base body 111 <sep> connection area 112 <sep> annulus 113 <sep> needle protection 114 <sep> annulus 115 <sep> outer wall 116 <sep> leading edge 117 <sep> Guide bar 118 <sep> needle holder 120 <sep> hollow needle 121 <sep> liquid channel 130, 130 ́ <sep> detection area 131 <sep> longitudinal groove 132 <sep> bore 200, 200 ́ <sep> optical element 210 <sep> main section 211 < sep> underside 212 <sep> light coupling surface 213 <sep> light decoupling surface 214 <sep> upper side 215 <sep> side surface 216 <sep> alternative cross section 220 <sep> feed section 221 <sep> feed groove 222 <sep> through-hole 230 <sep> underside 231 <sep> Longitudinal groove 232 <sep> Distribution chamber 233 <sep> Pressure compensation chamber 300 <sep> Control device 301 <sep> Drive motor 302 <sep> Medication reservoir 303 <sep> Line 304 <sep> Acoustic signal transmitter 305 <sep> Optical signal transmitter 310 <sep> Base unit 320 <sep> cartridge 410 <sep> light source 411 <sep> incident 412 <sep> refracted light 420 <sep> light sensor 421 <sep> reflected li cht 430 <sep> light source 431 <sep> incident light 432 <sep> reflected light 433 <sep> refracted light 440 <sep> light sensor 441 <sep> reflected light 442 <sep> refracted light

Claims (16)

Anspruch [en] A device for detecting pressure in a liquid-conducting region of an administration device, comprising at least one detection capillary having a first, open end and a second, at least indirectly closed end, wherein the detection capillary is filled with a compressible gas at least in an area adjoining the second end is and is connected at its first end to the liquid-conducting area; a translucent optical element (200; 200) which immediately bounds the detection capillary to at least one side to form at least one interface, wherein the optical element has a light injection region (212; 236) for coupling incident light into the optical element and directing it to the interface at an angle of incidence such that the light at the interface undergoes higher internal reflection when the interface at the interface Gas is as if the liquid is at the interface, and wherein the optical element (200; 200) has a light extraction region (213; 236) for coupling out light reflected internally at the interface from the optical element (200; 200). The apparatus of claim 1, wherein the detection capillary (131; 231) is connected at its open end to a connection channel (221) connecting the detection capillary to the fluid-conducting portion (212). 3. Device according to spoke 2, wherein the connecting channel (221) is designed as a capillary. 4. The device of claim 3, wherein the detection capillary (131; 231) defines a longitudinal direction and wherein the connection channel (221) is bounded at least in part by an angled longitudinally extending feed region (220) of the optical element (200) located in a support for the optical element (200) extends into it. 5. Device according to one of the preceding claims, comprising a support (110) for the optical element (200), in which a groove (131) is formed, wherein the optical element (200) has a flat bottom which bounds the groove (131) along its longitudinal direction, and wherein the groove (131) bounded by the optical element (200) forms the detection capillary. The apparatus according to claim 5, wherein the light injection section (212) has a light coupling surface inclined to the flat bottom surface, and wherein the light extraction section (213) has a light extraction surface facing the light coupling surface with respect to a flat bottom surface and containing the longitudinal direction Symmetry plane is symmetrical. 7. Apparatus according to claim 1, comprising a support (110) for the optical element, wherein the optical element (200) has an underside which is sealingly mounted on the carrier (110) to form at least a first detection capillary and a second detection capillary extending parallel to the first detection capillary; wherein each of the detection capillaries has a first, open end and a second, at least indirectly closed end, and wherein each of the detection capillaries is filled with a compressible gas at least in a region adjacent to the second end and at its first end with the liquid-conducting region (121 ) connected is, wherein the optical element has at least one first and one second groove (231) parallel thereto on its underside so that the first detection capillary is partially delimited by the first groove and the second detection capillary is partially bounded by the second groove, wherein the first groove has a first interface (234) extending along a longitudinal direction between the optical element and the first detection capillary, and wherein the second groove has a longitudinally extending second interface (235) between the optical element and the second detection capillary, and wherein the first and second interfaces are angled relative to each other with respect to a direction perpendicular to the longitudinal direction such that light which passes from the light coupling region (236) of the optical element to the first interface (234) of the first groove and is internally reflected thereby, to the second interface (235) of the second groove to be reflected from there to the light extraction region (236). The device of claim 7, wherein the first and second interfaces form an angle of 90 ° with respect to each other such that light incident along an incident direction on the first interface (234) reflects off the first and second interfaces (235) is reflected against the direction of incidence of the second interface. 9. Apparatus according to claim 7 or 8, wherein the first and the second detection capillary are connected at its second end to a closed to the environment, common pressure equalization chamber (233). The apparatus of any of claims 7 to 9, wherein the first and second detection capillaries are connected at their first end to a common manifold space (232) for supplying the liquid to the respective detection capillary, and wherein the manifold space communicates with the liquid-conducting area via a communication passage (121) is connected. The apparatus of any one of claims 7 to 10, wherein said optical element (200) has a plurality of parallel grooves (231) on its underside defining a plurality of parallel detection capillaries, each of said grooves having first and second planar flanks extending along the longitudinal direction, wherein the flanks enclose an angle of at least 90 °, wherein the first flank of one of the grooves forms the first interface (234), and wherein the second flank of an adjacent flute forms the second interface (235). 12. Device according to one of the preceding claims, which further comprises: a controller (300) having a light source (410; 430) for coupling light into the light coupling region of the optical element (200; 200) and a light sensor (420; 440) for light reflected internally at the interface in the optical element in the light outcoupling region from the optical element, wherein the control device (300) is adapted to detect a measure of the amount of internally reflected light. An administering device for administering a liquid medicament, comprising a product container (302) for the liquid medicament, having an outlet; a drive means (301) for expelling the liquid medicament from the container under pressure by the outlet; such as An apparatus according to claim 12, wherein the open end of the detection capillary communicates with the outlet of the container (302), and wherein the control means (300) is adapted to increase the pressure based on the amount of light received by the light sensor (420; 440) Detect in the liquid drug and deliver an alarm signal at a pressure rise above a threshold. 14. The delivery device of claim 13, which comprises: a reusable base unit (310) comprising the drive means (302) and the control means (300) with the light source (410; 430) and the light sensor (420; 440); a replaceable cartridge (320) including the liquid drug product container (302) and connectable to the base unit (310) for expelling the liquid medicament from the product container (302); and an adapter (100; 100) connectable to the cartridge (320) to connect an infusion set to the cartridge and comprising a fluid conduit (121; 303) for delivering the liquid medicament from the outlet of the product container (302) to the cartridge To direct the infusion set, wherein the at least one detection capillary is formed on the adapter (100; 100) and is connected at its open end to the fluid line (121; 303). 15. An adapter (100; 100) for connecting an infusion set to an administering device comprising a mounting portion for attaching the adapter to an administering device; a terminal portion (111) for connecting the infusion set to the adapter; a liquid conduit (120, 121) extending from the attachment region to the attachment region; such as An apparatus according to any one of claims 1 to 12, wherein at least one detection capillary is connected at its open end to the fluid conduit. 16. A method of pressure sensing in a fluid-carrying region of an administration device, comprising: Providing a detection capillary, having a first, open end and a second, at least indirectly closed end, wherein the detection capillary is filled at least in a region adjacent to the second end with a compressible gas and is connected at its first end to the liquid-conducting region, and wherein the detection capillary is limited to at least one side, forming at least one interface directly by a translucent optical element (200, 200), Directs incident light onto the interface such that the light incident through the light launching region strikes the interface at an angle at which the light at the interface undergoes internal reflection when the gas is present at the interface, and wherein Light at the interface undergoes reduced reflection when the liquid is in the area of the interface; Detecting light reflected at the interface; and Determining a measure of the pressure in the liquid-conducting region based on the amount of light detected at the interface.