DE102004040441A1 - Apparatus and method for determining the level of an ampoule - Google Patents

Abstract

The invention relates to a device for determining the level of a substance in an ampoule having at least two electrodes, between which the substance can be introduced; and to a method for determining the level of a substance in an ampoule having at least two electrodes, wherein the determination of the level is performed by measuring the capacitance of at least one capacitor formed by the at least two electrodes, wherein the dielectric constant of the at least partially between the at least two electrodes lying substance affects the capacitive coupling of the at least two electrodes.

Description

The The present invention relates to an apparatus and a method for determining the filling level an ampoule, in particular for determining the filling amount of a substance in one Ampoule or in a reservoir, for example in the medical Area in a drug reservoir of an infusion or injection device, wherein the Scope mainly in the surveillance and regulation of syringe pump type drug pumps, such as extracorporeal insulin pumps, or other dosing systems, such as Medicament pens or dialysate vials for microdialysis.

at the medical use of infusion or injection devices the exact dosage and delivery of a substance which is both solid and also liquid may be, such as insulin, hormone preparations or the like, important. This becomes common the level or the filling quantity the substance in an inserted into an infusion or injection device or insertable ampoule. For one thing, in such a Device monitored can be whether the set amount of substance was delivered or at all ready for delivery. On the other hand, it should be noted can, like the level the ampoule or the reservoir is.

The US 6,362,591 B1 relates to an apparatus and method for automatically detecting occlusion or malfunction of a drive system in a medical infusion system. In this case, the electric current is measured to an infusion pump and when a threshold value is exceeded, an alarm is triggered, whereupon the motor of the pump is moved back to reduce the fluid pressure in the system.

The DE 198 40 992 A1 relates to a method for monitoring the pressure of a product fluid to be dosed in an infusion or injection, which can be released from a container by advancing a piston. Here, a force exerted by the piston on the housing reaction force is measured and fed to a controller for driving the piston, which controls the drive of the piston taking into account a comparison result.

From the US 6,542,350 B1 For example, there is known a device for dispensing a medicament in which only the volume of a container is measured by means of a condenser, the capacitance of the condenser changing with the position of a bellows.

It is an object of the present invention, an apparatus and a method for simple and energy-saving determination of filling level or the filling quantity a substance in an ampoule or in a reservoir to enable.

These Task is governed by the objects of independent claims solved. Advantageous embodiments emerge from the dependent claims.

The inventive device for determining the filling level an ampoule has at least two electrodes, between which one in particular for medicinal substance usable substance, which both solid as well as liquid can be, can be introduced. In particular, too 3, 4, 5 to 20 or more than 20 electrodes be provided between which the substance can be introduced. It is under the Term "between" in the sense of the invention understood that the introduced substance as a dielectric at least a capacitor acting from the at least two electrodes is formed, in the area of which the substance is located. there the substance does not necessarily have to It may be the only dielectric of the capacitor, but it can also other materials, such as components of the infusion or injection device or the ampoule, in particular a contained in the infusion or injection device Plug, or air between the capacitor plates lie. includes the device of the present invention, for example, two electrodes, so For example, the substance stored in an ampoule can be so between serving as capacitor surfaces Electrodes lie that the two electrodes depending on the level the ampoule at least partially over the substance acting as a dielectric is capacitively coupled. Includes the device according to the invention For example, the substance may be between the three electrodes Electrodes are that they serve as a dielectric for at least one of two the capacitor formed of the three electrodes acts, with preference at least two of the three electrodes as capacitor plates over the Dielectric are capacitively coupled to each other. 4, 5 to 20 or more As 20 electrodes are preferably arranged so that a substance dependent on from the degree of filling an ampoule as a dielectric of one or more pairs of electrodes formed capacitors acts.

A capacitive level measurement of the ampoule according to the invention can also be carried out if the substance in the ampoule is not in extends the region of the electrodes, so the substance is not between the capacitors formed by electrodes. If electrodes are arranged, for example, in the region of the outlet opening or at the opposite end of the ampoule, it can be determined whether the ampoule has already been completely emptied or completely filled.

In the device for determining the level of the ampoule is that is, the difference in the relative dielectricity of air, the substance or the drug and / or parts of the Infusion or injection device or the ampoule exploited to determine the capacity by capacitance or capacitance measurements level or the filling quantity a substance in an ampoule or in a reservoir determine.

Advantageous At least one of the electrodes is designed so that they are in their length about the ampoule length corresponds and prefers the length of the Ampoule that can be filled with a substance, or the length of the Ampoule in whose area measurements can be made, which hereinafter referred to as "active Ampoule length "is called. Thus, at least one of the electrodes preferably extends over the entire ampoule length or the entire active ampoule length, so it has the same Length like the ampoule or as the fillable with a substance part the ampoule.

extend For example, exactly two electrodes over the entire length of Ampulle, this results in a device according to the invention, with each level the ampoule through the capacitive coupling of the electrodes and consequently also every filling quantity the substance in the ampoule can be detected if, for example the ampoule geometry, so for example the inner diameter or also other parameters are known. Here is the level for example, with a suitable arrangement of the electrodes to the measured capacitance value of the capacitor formed by the electrodes. A low level leads accordingly to a small measured capacitance value. In contrast, can from a high measured capacitance value of the capacitor a high level and consequently a high capacity the substance in the ampoule be closed.

The for example, on or near The ampoule provided electrodes can take various forms in dependence of the type or shape of the ampoule or the infusion or injection device. In a preferred embodiment According to the present invention, at least one of the electrodes is flat and / or bent and / or annular and / or strip-shaped and / or is in the form of cylinder jacket segments. Consequently, each of the at least two electrodes can be shaped differently be, i. it can any combination of shapes possible be. However, it is also possible for each of the at least two electrodes to have the same shape, such as a ring shape, strip shape or the shape of cylinder shell segments exhibit.

at a preferred embodiment According to the invention, the at least two electrodes are arranged that they are cut from one level at least in one place, with the ampoule inserted is perpendicular to the ampoule longitudinal axis. Preferably, the at least two electrodes are arranged that at least in one area of the ampoule from the perpendicular cut together on the ampoule axis normal planes become. The at least two electrodes are arranged, for example, that they are in the longitudinal direction the ampoule or the infusion or injection device at least partially overlap. Preferably, the at least two electrodes are in the longitudinal direction arranged the ampoule or the infusion or injection device so that at least two electrodes overlap in the longitudinal direction at least partially. It can For example, two electrodes facing each other so that one electrode Completely or, for example, three quarters, half, a quarter, or only minimally overlapped by the other electrode. The electrodes can be formed in the circumferential direction of the ampoule next to each other, as long as they are, in the preferred embodiment, in the longitudinal direction the ampoule or the infusion or injection device at least partially overlap, so cut off from one level at least in one place, with inserted ampoule perpendicular to the ampoule longitudinal axis stands. But this cutting plane is merely an imaginary auxiliary plane to check if overlap at least two electrodes at least at one point in the longitudinal direction, to see. For example, two electrodes face each other so that they are in the longitudinal direction the ampoule or the infusion or injection device at least overlap at one point, so can At this point, they are connected to each other by capacitive coupling as capacitor surfaces of the act through it formed capacitor. Thus, the respective overlapping surfaces of the serve at least two electrodes for forming a capacitive coupling and thus to the formation of one or more capacitors with those capacitance measurements carried out can be resulting in dielectric properties between the electrodes or the capacitor surfaces lying substance and thus closed on the substance itself or the level of the substance can be.

At least one is particularly preferred the electrodes arranged in the circumferential direction of the ampoule or the infusion or injection device. In this case, a plurality of electrodes may be arranged in the circumferential direction so that they are spaced next to each other or overlap in the circumferential direction and are preferably arranged separately from each other in the longitudinal direction.

Advantageous the electrodes are arranged so as to be spaced from each other from 0.1 to 7.0 mm. It can each have a same specific Distance between the electrodes to be chosen, the electrodes can However, also different distances from each other in the longitudinal and / or circumferential direction have from said distance range.

Of Further can the electrodes are preferably arranged so that they are in the longitudinal direction of the ampoule next to each other and / or offset from each other, where they are for Example are arranged mutually shifted in the circumferential direction. In this case, for example, one electrode may lie opposite a plurality of electrodes, in the longitudinal direction the ampoule or the infusion or injection device next to each other and / or staggered to each other, each one of which at the point where it overlaps with the opposite electrode, with the opposite electrode is capacitively coupled and thus forms a capacitor with this. Consequently, many capacitor pairs can be formed if, for example, a long electrode has multiple short electrodes across from lies or a plurality of electrodes is opposite.

According to one preferred embodiment of present invention is the device for determining the level a substance equipped with an ampoule, in which the substance may be contained or the substance may be introduced. there the ampoule can be placed in the infusion device designed as a disposable device or injection device be included, so for example be firmly connected to this, or can be used as a reusable device trained infusion or injection device be introduced and removed again.

Preferably are at least one and for example all the electrodes on the Ampoule arranged. In this case, the at least one electrode is special preferably on the exterior of the Arranged ampoule and is particularly firmly integrated into the ampoule, i.e. she is an integral part of the ampoule, respectively of the reservoir and is therefore at each change of the reservoir or the ampoule also exchanged. This is particularly advantageous because in this arrangement the at least one or for example also all electrodes as an integral part of the ampoule or of the reservoir, for example measurement errors due to contamination the ampoule for example by fingerprints, largely excluded can be. For the Applying the electrodes on the ampoule are different from the For example, a method known in the art can be used Screen printing, vapor deposition or electroplating. As well The electrode system can also be at least partially metallized film or formed by a flex-print and for example by an adhesive layer with preferably known dielectric Properties applied to the ampoule or the reservoir become. It is also possible the electrodes in the production process directly into the walls of the reservoir. These different methods of Applying or integrating into the ampoule can of course also be arbitrary be combined with each other, so that, for example, an electrode directly on the ampoule, an electrode on an adhesive layer the ampoule and an electrode is integrated into the ampoule. Independent of the realization is preferably a corrosion protection, for example by hard gold plating, provided.

Prefers the ampoule on a recognition element, which data, such as For example, ampule-specific calibration data, contained respectively can save. This recognition element can be particularly simple formed as a specific characteristic surface profile on the ampoule which, for example, due to depressions or elevations the surface of the Ampoule conclusions on the stored data permits. The calibration data can but also for example in a known from the prior art Barcode be stored, from which the data, as known, read out can be. On the ampoule can also be a transponder as a recognition element be provided, which the stored ampule-individual Send information as needed. In the case of the contained or stored Information can be any type of data that for calibration of the ampoule or the infusion or injection device can be used such as the size, the Shape, material or capacity of the ampoule used.

According to a further preferred embodiment of the invention, the device for determining the filling level of a substance in an ampoule comprises an infusion or injection device in which the ampoule is contained or into which the ampoule can be introduced. This infusion or injection device may include a syringe pump type drug pump such as extracorporeal insu or other dosing system, such as drug pens or dialysis vials for microdialysis.

is at least one of the electrodes is arranged on the ampoule is these preferably from an associated on the infusion or injection device contacted contact element arranged. These contact elements can for Example designed in the form of spring-mounted pins or contact springs and so for example when inserting an ampoule on electrodes to press. To wear To avoid electrodes and contact elements, the contact elements before inserting the ampoule or the reservoir into the infusion or injection device at a distance from the associated ones Electrodes should be located remotely and not contact them. Only after the introduction of the ampoule or the reservoir into the infusion or injection device, the contact elements brought into contact with the electrodes. In addition to this direct, electrical Contacting of the electrodes by the contact elements are also other contacts conceivable in which no direct physical contact, i. no contact between the contact elements and the associated electrodes exists. So can the contact elements in turn also be designed as electrodes, with a respective associated, arranged on the ampoule, measuring electrode by capacitive coupling to contact. Preferably, an anti-rotation device provided for a correct and reproducible alignment with respect to the To ensure contact elements.

It can Also, at least one or all electrodes disposed on or in the infusion or injection device being, including embodiments possible are where some of the electrodes on the ampoule and a Part of the electrodes arranged on the infusion or injection device are. If the entire electrode system is a component of the infusion or injection device, so it will not be changed together with the ampoule, but remains when replacing the ampoule in the infusion or injection device. At this embodiment the device of the present invention corresponds advantageously the inner contour of the electrodes of the outer contour of the ampoule, i. the electrodes are at a constant distance at each point or touch the ampoule these.

The at least one electrode may also be applied to a carrier, whose Inner contour of the outer contour the ampoule corresponds, so that the at least one electrode or the at least one carrier at each point a constant radial distance to that in the Infusion or injection device has lying ampoule or touched. This at least one Carrier exists advantageous from non-conductive material, in particular plastic, to isolate the conductive electrodes from the infusion or injection device. The at least one electrode as well as the at least one carrier can in this embodiment realized the present invention in different ways become. So can For example, the electrodes realized as a flex-print and in the carrier be glued. Alternatively you can the carriers even with the MID technology known metallization and structuring at least partially metallized, in turn on their surface as electrodes to act. Furthermore, preferably a high-quality corrosion protection, for example in the form of a hard gold plating, provided for the electrodes, to a defined coupling via the entire life of the device to ensure.

Advantageous is when using straps in the infusion or injection device on at least one of the carriers Attached pressure element, for example in the form of a pressure spring, which is a secure pressure of the carrier in the radial direction ensures the ampoule.

at a further embodiment of the invention the ampule is a plug of conductive or dielectric Material or a combination of these materials, preferably so in the ampoule that he has an empty or substance-free ampoule part separates from an ampoule part filled with the substance. It is under the empty ampoule part within the meaning of the invention understand that there is not the substance to be administered, but probably other substances or materials, such as Air or components of the device may be included. Especially Preferably, the plug is designed so that it along the ampoule longitudinal axis can be moved to, for example, administering the substance to enable. Of the Plugging may be due to its normally different dielectric Properties opposite Air or substance to be administered by capacity measurements from the filled and the empty or substance and stopper-free ampoule part be differentiated.

Furthermore, the device of the present invention preferably has a reading and / or evaluation unit for reading out and / or evaluating the calibration data of the recognition element. This reading or evaluating unit can be designed so that it can scan the surface of the ampoule, for example with the aid of a laser beam, in order to obtain conclusions about the already mentioned individual calibration data from the characteristic surface profile. However, the reading unit can also be used as a scanning device with an associated evaluation be formed device to win the information stored in a bar code information. The reading unit can also be designed as a reading or detection device of a transponder located on the ampoule in order to read out the ampoule-individual calibration data and to evaluate them in the associated evaluation unit.

Prefers includes the device for determining the level of a substance in an ampoule a temperature sensor, with which by measurement the temperature of the temperature coefficient of the measuring device by calculation can be compensated and / or active temperature compensation for example with a cooling or heating device performed can be.

at the method according to the invention for determining the filling level a substance in an ampoule by means of at least two electrodes is the capacitive coupling of at least two electrodes of the level the ampoule and thus the capacity of the substance in the ampoule. It influences the between the respective capacitor surfaces lying substance the capacity the capacitor arrangement due to their dielectric properties. This can easily determine which substance is between the respective capacitor surfaces or in the area of which the substance is condensed or at which position of the respective capacitor, the boundary layer or the level the substance is located. By evaluating the measured capacities of the through the respective overlapping ones Electrode pairs formed capacitors, the level of a substance. For example, there are two electrodes so opposite, that they overlap at least partially and thus a capacitor Forming can be done by measuring the capacitance of the capacitor on top of it lying dielectric and thus on the intervening substance getting closed. This can be used to determine what proportion of the Substance or to what proportion of air or another substance or Material between the electrodes is present, which is directly on the level or the filling quantity to close the substance in the ampoule.

Especially the level is preferred the substance to be administered by a two-step procedure according to the present Invention determined. At least three electrodes are arranged in this way that they overlap by form at least two single capacitors. By measuring the capacity at least one single capacitor can be determined in the range which single condenser is the boundary layer of the substance filled Area to the empty or substance-free area of Ampoule, i. in the area which single capacitor itself the level the ampoule is to derive therefrom the amount of that contained in the ampoule To determine substance.

In A second step can now be done by measuring the capacity of that one Single capacitor or those single capacitors, where the boundary layer is, the exact position the boundary layer and thus the exact level can be determined. For this can in particular also the measured capacitance or values and / or information about the dielectric constant the substance can be used. This multi-step process for Measurement of the level of the Substance in the ampoule offers the advantage of greater accuracy and safety, because the dynamic range or range of the measurement by one Factor is reduced by the number of electrodes used depends. For example, if there are N single electrodes of an electrode with one the active length the ampoule corresponding length, wherein from the first step of the two-stage process is known in Range of which of the N individual electrodes is the level or the boundary layer of substance-filled and substance-free area, only needs to be determined at which point or position of the determined individual electrode itself the level or the boundary layer is located. The through this single electrode with the opposite Electrode formed capacitor has a maximum capacity, which is the 1 / N times the maximum capacity a capacitor corresponds, in which the N-single electrodes through a single electrode to be replaced, the area of the total area of Corresponds to N individual electrodes. The dynamic range is corresponding the capacity measurement when using N single electrodes and thus of N single capacitors lower by a factor of N while the required resolution of the Measurement does not change. additionally elevated also the safety when using N-single electrodes, because the formed N-Einzelkapazitäten an additional absolute scale the resolution I / N represent, where l denotes the active ampoule length.

Preferably, the level of the substance in the ampoule can be determined by determining the stopper position in the ampoule. In this case, a measurement of the capacitance of at least one capacitor formed by the at least two electrodes is carried out, between which at least part of the plug is located. The dielectric constant of the plug affects the capacitive coupling of the at least two electrodes and results in the measurement of a different capacitance value as compared to the measurement of the capacitance of the capacitor formed by the same electrodes at least a capacitor containing as a dielectric, for example, the substance or air to be administered. About the position of the plug can now be closed on the level of the substance in the ampoule.

Of Further, the position of the plug in the ampule and thus the level the ampule too a measurement of the total capacity three parallel connected capacitors. It forms the empty or substance-free and stop-free area of the Ampoule the dielectric of the first capacitor, the plug the Dielectric of the second capacitor and filled with the substance area the dielectric of the third capacitor. The capacitor surfaces of the respective capacitors must not necessarily be separate electrodes. It is also possible by means of two electrodes, between which the substance-filled area, the plug and the empty area of the ampoule lie, the capacities of the to determine respective individual capacitors and by their parallel connection the total capacity to investigate. Likewise however, more than two electrodes can be used. By measurement the total capacity can with knowledge of the relative dielectric constant of the used Substance, the plug material used and the empty Be rich, immediately the stopper position in the ampoule and thus the level the ampoule are calculated.

In addition, can prior to each of the described embodiments for determination the level the substance in the ampoule in the filled state of the ampoule one Reference measurement of capacity or the capacities at least one capacitor formed by the at least two electrodes carried out become. This in turn can increase the accuracy of the method according to the invention be reached, since now a reference value of the capacity or the capacities to disposal by measuring the capacitance of at least one capacitor was obtained, the dielectric, for example, exclusively from the substance to be administered. This leads in particular to an increase in accuracy the measurement, as factors that affect the measurement undesirably, such as measurement inaccuracies due to, for example, soiling or abrasions of the components of the device, diminished respectively can be eliminated.

so kann bei jeder Berechnung des Kapazitätsverhältnisses c der Kapazitätswert eines Kondensators neu in den Zähler aufgenommen werden, was in obiger Glei chung einer Erhöhung des Wertes x, x ∊ [1....N], entspricht, womit zum Beispiel aus einem Vergleich der Kapazitätsverhältnisse auf den Einzelkondensator geschlossen werden kann, an welchem sich die Grenzschicht beziehungsweise der Füllstand der Substanz befindet. Befindet sich zum Beispiel eine Substanz wie ein Medikament mit höherer Dielektrizitätskonstante als Luft in der Ampulle, so werden die Kapazitätswerte C₁ bis C_x-1 der Kondensatoren, zwischen denen sich die Substanz nicht befindet, kleiner sein als die Kapazitätswerte C_x bis C_N, an denen sich die Substanz zumindest teilweise befindet. Folglich kann in diesem Beispiel aus dem minimierten Wert des Kapazitätsverhältnisses c leicht ermittelt werden, im Bereich welches Einzelkondensators oder welcher Einzelelektrode C_x sich die Grenzschicht beziehungsweise der Füllstand der Substanz befindet.In particular, when determining the filling level of the ampoule with the aid of the capacitors formed from the electrodes, both absolute capacitance values, ie the respective measured value of the capacitor, and ratios of measured capacitance values can be used. For example, with the use of N single electrodes and an electrode opposite the N individual electrodes, the filling level of the ampoule can be determined by the formation of capacitance ratios, for example, so that capacitance ratios are formed until a certain value of the capacitance ratio is reached. For example, if you form the ratio c

Thus, with each calculation of the capacitance ratio c, the capacitance value of a capacitor can be newly included in the counter, which in the above equation corresponds to an increase in the value x, x ε [1 .... N], which, for example, results from a comparison of Capacitance ratios can be closed to the single capacitor, at which the boundary layer or the level of the substance is located. For example, if a substance such as a drug having a higher dielectric constant than air is in the vial, the capacitance values C ₁ to C _{x-1 of} the capacitors between which the substance is not located will be smaller than the capacitance values C _x to C _N where the substance is at least partially located. Consequently, it can easily be determined in this example from the minimized value of the capacitance ratio c, in the region of which individual capacitor or which individual electrode C _x the boundary layer or the fill level of the substance is.

With Help the geometry of the ampoule and / or the dimensions of the ampoule and / or information on dielectric properties of the ampoule and / or the contained therein Substance or a substance displacing the substance during the dispensing process can in the inventive method advantageous in addition to the determined level the capacity the substance in the ampoule. This is special then helpful, for example, to determine whether the entire amount of the substance has been administered or to determine whether the desired Quantity, for example those set on an infusion or injection device Amount, was administered.

Preferably is used in determining the stopper position or the Level or the capacity in an ampoule in addition an active temperature compensation performed to the accuracy and Safety of the measurement or the measurements to increase.

Preferably, the present device can also be used to determine the nature of a substance in the ampoule or in the reservoir. By measuring the capacitance value of at least one capacitor formed by at least two electrodes, for example Knowing the dielectric properties of various substances on the nature of the substance are GE closed. In particular, it is also possible, for example, to use N individual electrodes and one opposite electrode to form many, in particular N, individual capacitors, from whose capacitance values the type of substance is determined by means of known dielectric values of different substances. For example, it would be possible to deduce the dielectric constant of the substance from the measured capacitance values knowing the overlap of the respective electrodes or the filling level or the filling quantity of the substance, which can be compared, for example, in a look-up table with known dielectric constants, to obtain the value the dielectric constant directly to determine the substance.

Preferably can, for example, in a defined filling state of the ampoule, such as at complete filled Ampoule, the type of substance are determined and then by means of one listed herein Process, in particular cyclically, determines the level of the ampoule become.

Especially can all of the described methods for determining the level the or the filling quantity be used in the ampoule to determine the type of substance. Preferably, it is first the level or the capacity of the Substance in the ampoule determined and then, for example, under note the dielectric properties of various substances a determination the type of substance performed.

The Invention will be described below with reference to preferred embodiments to be discribed. Show it:

1 an injection device according to a first embodiment of the present invention;

2a and 2 B an ampoule with capacitive Füllmengenmessung according to a two-th embodiment of the invention in longitudinal section and in cross section;

3 a measured capacity and its regression line as a function of the released substance volume;

4 a development of the cylinder circumference of an ampoule with capacitive level or Füllmengenmessung;

5 an improved form of the measuring device according to 4 with segmented electrode;

6 an example of measured individual capacities of the arrangement according to 5 ;

7a and 7b a schematic representation of a possible contact arrangement in the withdrawn state and in the working state;

8th a schematic representation of an electrode assembly as part of the infusion or injection device.

1 schematically shows an ampoule or a reservoir 1 in an infusion or injection device 1a , in which among other things a reading unit 16 and an evaluation unit 17 , as well as a temperature sensor 18 are included. At one point is on the ampoule 1 a recognition element 15 applied. In addition, there are two electrodes on the ampoule 2a and 2 B , as well as in the ampoule 1 a substance to be administered. The two electrodes 2a and 2 B have the same length both in the longitudinal and in the circumferential direction of the ampoule 1 In particular, approximately completely overlap, resulting in a relatively good capacitive coupling between the electrode 2a and the electrode 2 B is obtained. Between the two electrodes 2a and 2 B There is a substance-filled area in the ampoule 5 and an area not filled with substance or filled with air 4 , which due to their different dielectric properties, the capacitive coupling of the electrodes 2a and 2 B vary greatly. This difference in dielectric constant of the substance to be administered, for example, a drug such as insulin, to air is usually given, since the dielectric constant of most drugs is significantly greater than that of air. Consequently, the electrodes acting as capacitor surfaces between the two will become 2a and 2 B change measured capacitance value as a function of the level or the amount of substance in the ampoule. In general, an increase in the amount of substance due to the higher dielectric constant compared to air will lead to an increase in the measured capacitance value and a decrease in the amount of substance to a decrease in the measured capacitance value. Thus, a measured capacitance value can clearly indicate a certain fill level and with the help of the geometry and dimensions of the ampule, which can be detected by a detection element 15 can be stored on the ampoule and by a reading unit 16 read out and / or an evaluation unit 17 can be evaluated, assigned to a specific unique fill quantity.

2a and 2 B show a second embodiment of the present invention, wherein additionally a plug 3 , for example made of rubber or plastic, in the ampoule 1 is included and one empty or substance and stopper-free or air-filled ampoule part 4 from a substance filled part 5 separates. The promotion of the substance is carried out by a movement of the plug 3 along the ampoule longitudinal axis 6 opposite to the direction indicated by s. Again, the capacitive level measurement by means of two electrodes 2a and 2 B performed in the form of cylinder jacket segments whose inner contour of the outer contour of the ampoule 1 equivalent. Also these two electrodes 2a and 2 B correspond in length to the active ampoule length l and point in the circumferential direction of the ampoule 1 from each other a certain distance from a distance range of 0.1 to 7.0 mm, so are by two columns 8a and 8b separated from each other. Electrically, this arrangement corresponds to a parallel connection of three capacitors C ₁ , C ₂ and C ₃ , wherein the first capacitor C ₁ through the two electrodes 2a and 2 B as capacitor surfaces and the empty part 4 the ampoule 1 is formed as a dielectric, the second capacitor C ₂ through the two electrodes 2a and 2 B as capacitor surfaces and the plug 3 is formed as a dielectric and the third capacitor C ₃ through the two electrodes 2a and 2 B as condenser surfaces and the substance-filled ampoule part 5 is formed as a dielectric. Also in this arrangement, the different dielectric constants of air, substance and plug affect the measured capacitance values. For the total capacitance C, due to the parallel connection of the three capacitors, the linear relationship with the plug position s results: C = C 1 + C 2 + C 3 = (l - s) C ' 1 + C 2 + sC ' 3 where C ' ₁ and C' ₃ denote the length-related capacitances given by the geometry and the relative dielectrics, and as a rule C ' ₃ >C' ₁ . By virtue of this relationship, by measuring the total capacitance C directly, the plug position s in the ampule 1 and the proportional level in the ampoule 1 are calculated, which in turn determines the amount of substance in the ampoule 1 can derive.

In 3 By way of example, the capacitance C _{measured measured} in an experiment is shown as a function of the substance or medicament volume released from the ampoule or the reservoir for a standard insulin ampule and physiological saline solution as the test fluid. The comparison with the regression line C _fit , which is also shown, shows an overall good linearity. The visible remaining nonlinearity from about 200 IU results essentially from the non-ideal, manual adjustment of the electrodes.

In the arrangements according to 1 and the 2a and 2 B The capacity measurements are performed in a wide dynamic range, so that a high resolution for an accurate determination of the level must be obtained. Thus, for example, for a 300 IU insulin ampule, which corresponds to a content of 3 ml insulin of insulin concentration of U100, at a required resolution of 0.1 IU, the dynamic range is at least 1: 3000, the dynamic range in this regard being the ratio of the required resolution of 0.1 IU and the measurement range, 300 IU.

The arrangement according to 5 instead of in 4 to be recognized arrangement of a developed cylindrical ampoule lateral surface with the two electrodes 2a and 2 B whose length corresponds to the active ampoule length, as in 1 and 2 shown points instead of the second electrode 2 B a series of N (here with N = 20) single electrodes 2b ₁ . 2b ₂ , ... 2b _N on which along the ampoule longitudinal axis on the opposite side of the electrode 2a are arranged. With the aid of this arrangement, instead of the single-stage analog measurement of the filling level, a two-stage measurement of the filling level can be carried out, which leads to a lower dynamic range and thus to a more accurate measurement.

As can be seen, in this arrangement, N single capacitors resulting from the first electrode 2a with the N opposite individual electrodes 2b ₁ . 2b ₂ , .... 2b _N be formed. In a first step, the capacitance values of the N individual capacitors are first determined by measurements, which can be carried out both simultaneously and sequentially, in order to determine in the region of which electrode 2b _x with x ε [1 ... N] the boundary layer of the substance with the empty area or the substance with the stopper is located. This first step can be regarded as a first discrete measurement, because of a finite number of N single capacitors that single capacitor and thus that electrode 2b _X is determined in whose or in whose area the boundary layer is located. For the determination of the exact filling level or the exact filling quantity, the capacity of the one electrode is then subsequently determined in a second step, which is carried out with an analog measuring method 2a and the electrode 2b _x , in the region of which the boundary layer or the fill level is located, the capacitor formed is measured or the capacitance value measured in the first step is evaluated. As the capacitor area of the electrode 2b _x N times smaller than the capacitor area of the electrode 2 B out 4 is also the maximum capacity of the measured single capacitor from 5 1 / N times the maximum capacity of the capacitor according to 4 while the resolution of Mes does not change. This also reduces the dynamic range of the through the electrodes 2a and 2b _X formed capacitor N times compared to that by the electrodes 2a and 2 B formed capacitor 4 , In addition to the lower dynamic range of the capacitance measurement has an arrangement according to 5 with segmented electrode 2b ₁ . 2b ₂ , ... 2b _N the advantage of greater safety, since the N individual capacities represent an additional coarse absolute scale of resolution I / N, where l corresponds to the active ampoule length.

An example of measured individual capacitances C _n , n ε [1 ... N] shows 6 for N = 20 individual electrodes, wherein the fill level or the substance-air boundary layer or the substance-stop boundary layer is located at the ninth electrode. In the area of the first eight electrodes, air is in the form of a dielectric, which leads to a low or minimum capacity C _min . The ampoule space between the individual capacitors 10 to 20 is filled with a substance or a medicament whose dielectric constant is greater than that of air, which results in a higher or maximum measured capacitance C _max . In the region of the ninth capacitor there is a sudden increase in the measured capacitance value, the value of which lies between the minimum capacitance value, in the case of air as dielectric, and the maximum measured capacitance value, in the case of the substance as dielectric, since in the region of the ninth electrode both air and Substance is present and thus enter both associated dielectric constants in the calculation of the capacity of the ninth capacitor. The exact position of the filling level or of the boundary layer at the ninth electrode or at the ninth capacitor can now be determined from this capacitance profile, which can now be processed both internally and as an intermediate result, by measuring and evaluating the capacitance value taking into account the dielectric properties of the substance.

7a and 7b show schematically an arrangement in which the electrodes 2a . 2b ₁ and 2b ₂ on the ampoule 1 are attached and by contact elements, as here metallic bending springs 9a . 9b ₁ and 9b ₂ , be contacted. Before and during the insertion of the ampoule or the reservoir are, as in 7a represented, the bending springs 9a . 9b ₁ and 9b ₂ in an initial state, ie it exists between the electrodes 2a . 2b ₁ and 2b ₂ and the associated contact springs 9 ₁ . 9b ₁ and 9b ₂ one gap each 10 so that the contact springs 9a . 9b ₁ and 9b ₂ and the electrodes 2a . 2b ₁ and 2b ₂ Do not touch during insertion to ensure smooth insertion of the ampoule and thus wear on the electrodes 2a . 2b ₁ and 2b ₂ and on the contact springs 9a . 9b ₁ and 9b ₂ to reduce or prevent. Only when the ampoule has been completely inserted into the infusion or injection device, the gap 10 for example, automatically or by the actuation or the triggering of a triggering element closed, the electrodes 2a . 2b ₁ and 2b ₂ So for example by a radial movement of the contact springs 9a . 9b ₁ and 9b ₂ through the contact springs 9a . 9b ₁ and 9b ₂ contacted, what in 7b is illustrated. The triggering element may be provided on or in the infusion or injection device and, for example, by inserting the ampoule 1 be triggered or operated for example by the user.

For applying the electrodes 2a . 2b ₁ and 2b ₂ Various methods known in the art may be used on the ampoule, such as screen printing, vapor deposition or electroplating. Furthermore, the electrodes can 2a . 2b ₁ and 2b ₂ are on an at least partially metallized film or formed by a flex-print or the like and permanently applied for example by means of an adhesive layer of known dielectric properties on the ampoule or the reservoir. It is also possible, at least one of the electrodes 2a . 2b ₁ and 2b ₂ In the production process to integrate directly into the walls of the ampoule or the reservoir or one of the electrodes 2a . 2b ₁ and 2b ₂ form as ampoule or reservoir itself. Regardless of the exact nature of the realization of electrodes 2a . 2b ₁ and 2b ₂ and contacts 9a . 9b ₁ and 9b ₂ can by a rotation of a correct and reproducible alignment of the electrodes 2a . 2b ₁ and 2b ₂ concerning the contacts 9a . 9b ₁ and 9b ₂ be ensured. It is also possible to apply corrosion protection to the electrodes, for example by means of hard gold plating, in order to ensure good contacting of electrodes 2a . 2b ₁ and 2b ₂ and contacts 9a . 9b ₁ and 9b ₂ over the entire life of the infusion or injection device.

8th shows a further embodiment of the present invention, in which all the electrodes 2a . 2b ₁ , and 2b ₂ , So the entire electrode system, are mounted on the infusion or injection device or the pump and thus are an integral part of the infusion or injection device. Here are the ampoule for clarity 1 and the three electrodes 2a . 2b ₁ and 2b ₂ slightly separated from each other. The electrodes 2a . 2b ₁ and 2b ₂ are in this arrangement on carriers 12 . 13 applied, which consist in this embodiment in particular of non-conductive material such as rubber or plastic, wherein the inner contour of the carrier or the dar on attached electrodes 2a . 2b ₁ and 2b ₂ the outer contour of the ampoule 1 equivalent. To over the entire circumference of the ampoule safe pressure of the support elements 12 . 13 to the three electrodes 2a . 2b ₁ and 2b ₂ and / or a safe pressure of the electrodes 2a . 2b ₁ and 2b ₂ to the ampoule 1 to ensure is on at least one of the two support elements 12 . 13 one on the carrier 12 . 13 acting pressure element, for example a pressure spring 14 , appropriate. In the present arrangement according to 8th is the carrier element 12 with a pressure spring 14 provided and thus performed resiliently in the radial direction. The electrodes 2a . 2b ₁ and 2b ₂ as well as the carriers 12 . 13 This arrangement can be realized in different ways. First, the electrodes 2a . 2b ₁ and 2b ₂ realized for example as a flex-print and in the carrier 12 . 13 be glued. Alternatively, the support elements 12 . 13 Even with metallization and structuring methods known from MID technology, they are at least partially metallized, so as to have the properties of one or more electrodes themselves. To ensure a defined coupling over the entire life of the infusion or injection device or the pump, is also here for the electrodes 2a . 2b ₁ and 2b ₂ a high quality corrosion protection required, for example in the form of a hard gold plating.

Claims (29)

Device for determining the level of a substance in an ampoule ( 1 ) with at least two electrodes ( 2a . 2 B ), between which the substance can be introduced. Device according to the preceding claim, wherein at least one of the electrodes ( 2a . 2 B ) corresponds in length to the ampoule length. Device according to one of the preceding claims, wherein at least one of the electrodes ( 2a . 2 B ) is flat, curved, annular or strip-shaped or has the shape of cylinder jacket segments. Device according to one of the preceding claims, wherein at least two of the electrodes ( 2a . 2 B ) are arranged so that the at least two electrodes ( 2a . 2 B ) are cut at least at one point from a plane which, with inserted ampoule ( 1 ) is perpendicular to the ampoule longitudinal axis. Device according to one of the preceding claims, wherein at least one of the electrodes ( 2a . 2 B ) in the circumferential direction of the ampoule ( 1 ) is arranged. Device according to one of the preceding claims, wherein the electrodes ( 2a . 2b ₁ . 2b ₂ , ... 2b _N ) have a distance of 0.1 to 7.0 mm from each other. Device according to one of the preceding claims, wherein at least two of the electrodes ( 2a . 2 B ) are arranged side by side in the ampoule longitudinal direction and / or offset from one another. Device according to one of the preceding claims with an ampoule ( 1 ). Device according to the preceding claim, wherein at least one of the electrodes ( 2a . 2 B ) on the ampoule ( 1 ) is arranged, in particular in the ampoule ( 1 ) is integrated. Device according to one of the two preceding claims, wherein the ampoule ( 1 ) a recognition element ( 15 ), in particular a transponder, a barcode or a characteristic surface profile which can store ampulla-specific data, in particular calibration data. Device according to one of the preceding claims with an injection device ( 1a ). Device according to the preceding claim, wherein at least one of the on the ampoule ( 1 ) arranged electrodes ( 2a . 2 B ) of an associated on the injection device ( 1a ) arranged contact element ( 9a . 9b ₁ . 9b ₂ , ... 9b _N ) is contacted or capacitively coupled with this. Device according to one of the two preceding claims, wherein at least one of the electrodes ( 2a . 2 B ) on or in the injection device ( 1a ) is arranged. Device according to the preceding claim, wherein at least one of the electrodes ( 2a . 2 B ) on a support ( 12 . 13 ), wherein the inner contour of the electrodes and / or the carrier ( 12 . 13 ) the outer contour of the ampoule ( 1 ) corresponds. Device according to one of the two preceding claims, wherein on at least one of the carriers ( 12 . 13 ) a pressure element ( 14 ) is attached. Device according to one of the preceding claims, wherein the ampoule ( 1 ) a stopper ( 3 ) of a conductive or dielectric material or a combination thereof. Device according to one of the preceding claims, wherein the device comprises a reading unit ( 16 ) and / or evaluation unit ( 17 ) for reading and / or evaluating the calibration data of the Erken element ( 15 ). Device according to one of the preceding claims, wherein the device comprises a temperature sensor ( 18 ) for active temperature compensation. Method for determining the level of a substance in an ampoule ( 1 ) with at least two electrodes ( 2a . 2 B ), wherein the determination of the filling level by measuring the capacitance of at least one of the at least two electrodes ( 2a . 2 B ) is carried out, wherein the dielectric constant of the at least partially between the at least two electrodes ( 2a . 2 B ) the capacitive coupling of the at least two electrodes ( 2a . 2 B ). Method according to the preceding claim, wherein at least three electrodes ( 2a . 2b ₂ , ... 2b _N ) form at least two individual capacitors and a measurement of the capacitance is carried out on at least one individual capacitor, in order to determine how large the quantity in the ampoule ( 1 ) contained substance is. Method according to the preceding claim, wherein for determining the exact position at which the boundary layer of the area filled with the substance ( 5 ) of the ampoule ( 1 ), a measurement of the capacitance is carried out on those individual capacitors in which the boundary layer is located and from the measured capacitance values and information about the dielectric constant of the substance, the fill level is calculated exactly. Method for determining the level of a substance in an ampoule ( 1 ) with at least two electrodes ( 2a . 2 B ), whereby the determination of the position of a plug ( 3 ) in the ampoule ( 1 ) by measuring the capacitance of at least one of the at least two electrodes ( 2a . 2 B ) is performed and the dielectric constant of the at least partially between the at least two electrodes ( 2a . 2 B ) plug ( 3 ) the capacitive coupling of the at least two electrodes ( 2a . 2 B ). Method according to the preceding claim, wherein to determine the position of the plug ( 3 ) in the ampoule ( 1 ) a measurement of the total capacitance of three capacitors connected in parallel is carried out, whereby the capacitance of a first capacitor is measured, which as dielectric the empty area ( 4 ) of the ampoule ( 1 ), the capacitance of a second capacitor is measured, which as dielectric the plug ( 3 ) and the capacitance of a third capacitor is measured, which as a dielectric substance filled area ( 5 ) of the ampoule ( 1 ) having. Method according to one of the five preceding claims, wherein in the filled state of the ampoule ( 1 ) a reference measurement of the capacitance of at least one of the at least two electrodes ( 2a . 2 B ) is performed. Method according to one of the six preceding claims, wherein a measurement of absolute capacitance values and / or a measurement of capacity ratios carried out becomes. Method according to one of the seven preceding claims, wherein with the aid of the geometry, the dimensions of the ampoule ( 1 ) and / or information on dielectric properties of the ampoule ( 1 ) and / or a substance contained therein from the level of the substance in the ampoule ( 1 ) a determination of the filling amount of the substance is carried out. Method according to one of the eight preceding claims, wherein an active temperature compensation is performed. Method for determining the type of substance, wherein from a measured capacitance value at least one of at least two electrodes ( 2a . 2 B ) formed capacitor or capacitor system and from known dielectric properties of various substances, the nature of the substance is determined. Method of determining the nature of a substance whereas, prior to the determination of the nature of the substance, a determination of the filling level according to one of the claims 19 to 27 performed becomes.