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WO1993004371A1 - Circuits analyseurs servant a analyser des echantillons sur des electrodes sensibles aux ions - Google Patents

Circuits analyseurs servant a analyser des echantillons sur des electrodes sensibles aux ions Download PDF

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Publication number
WO1993004371A1
WO1993004371A1 PCT/US1992/007100 US9207100W WO9304371A1 WO 1993004371 A1 WO1993004371 A1 WO 1993004371A1 US 9207100 W US9207100 W US 9207100W WO 9304371 A1 WO9304371 A1 WO 9304371A1
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WO
WIPO (PCT)
Prior art keywords
voltage
amplifier
sensor
circuit
electrode
Prior art date
Application number
PCT/US1992/007100
Other languages
English (en)
Inventor
John R. North
Robert L. Kay
Original Assignee
Porton Diagnostics Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Porton Diagnostics Inc. filed Critical Porton Diagnostics Inc.
Publication of WO1993004371A1 publication Critical patent/WO1993004371A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/483—Physical analysis of biological material
    • G01N33/487—Physical analysis of biological material of liquid biological material
    • G01N33/48785—Electrical and electronic details of measuring devices for physical analysis of liquid biological material not specific to a particular test method, e.g. user interface or power supply

Definitions

  • the present invention relates to circuitry for analyzing samples on ion sensitive electrodes and more particularly to amplifier circuitry within the analyzer.
  • ISE ion selective electrodes
  • these electrodes are used in conjunction with an analyzer as part of a diagnostic system.
  • a disposable sensor including such electrodes on-which a sample of fluid, such as blood, can be placed. Once the sensor is in contact with the analyzer and the fluid is in position on the sensor, the analyzer can provide an indication of an ion concentration in the blood sample, such as an indication of potassium concentration.
  • the analyzer is designed to have interaction with single-use sensors, sensors are constantly being attached and detached from the analyzer. This produces static caused by the friction between the sensor and the analyzer during the attachment and detachment operations. Furthermore, static may be transferred to the sensor and/or the analyzer from the body of the operator. This static can destroy an unprotected amplifier circuit in the analyzer, thereby rendering the analyzer device ineffective or unusable. Additionally, the state of the amplifier circuit, from open circuit to closed circuit, changes regularly with the attachment and detachment of the sensor. As a consequence, voltage transients occur in the system which can also negatively influence the measurements taken with the analyzer amplifier circuitry.
  • Sensors may be subjected to conditions that degrade the quality of the sensor package or possibly render it ineffective prior to its attachment to an analyzer.
  • the known analyzer is unable to detect the quality of the sensor presently attached to the analyzer and is unable to determine if it is necessary to discard a sensor before use.
  • the known analyzer is incapable of detecting the removal of a calibration gel disposed on an attached sensor and is further unable to detect when a sample of fluid has been applied to the sensor.
  • the present invention addresses each of the noted problems with the known analyzer by providing amplifier circuitry having a unique configuration and under the control a microcontroller driven by application specific software.
  • the present invention protects the analyzer amplifier circuitry from negative effects of static buildup due to attachment and detachment of sensors with respect to the analyzer.
  • the design provides enhanced quality assurance for individual sensors in use with the analyzer.
  • the analyzer accomplishes this by providing the capability of testing each sensor after it is properly positioned in the analyzer.
  • the amplifier circuit of the present invention provides the capability of detecting the removal of a calibration gel associated with the sensor, of detecting a deposit of a sample on the sensor, and of taking certain measurements at fixed time intervals following these detections.
  • the circuitry of the present invention provides the capability of measuring resistance across the ion sensitive electrode using the smallest possible current flow. This reduces any negative drifting resistance measurements which have been known to arise due to the effect of larger currents on the ion selective electrode configuration. The reduced current in the testing mode reduces the variation of the ISE.
  • Fig. 1 illustrates a cross sectional view of a disposable sensor used with an analyzer designed in accordance with an embodiment of the present invention.
  • Fig. IA illustrates an enlarged portion of the disposable sensor of Fig. 1.
  • Fig. 2 illustrates a schematic diagram of a closed loop amplifier circuit in an analyzer in accordance with an embodiment of the present invention.
  • Fig. 3 is a flow chart for a calibration algorithm implemented with the analyzer of the present invention.
  • Fig. 4 is a flow chart for a gel cap removal detection algorithm implemented in the analyzer of the present invention.
  • Fig. 5 is a flow chart for a sample-applied detection algorithm implemented in the analyzer of the present invention.
  • Fig. 6 is a flow chart for a sample measurement algorithm implemented with the analyzer of the present invention.
  • Fig. 7 is a table describing operational modes available to the analyzer of the present invention.
  • Fig. 1 illustrates a cross section of an embodiment of an sensor that uses ion selective electrode technology.
  • Fig. IA shows an enlarged view of a portion of the electrode of Fig. 1.
  • a substrate card 1 includes channels 2 for receiving electrodes 3. Two electrodes are illustrated. However, typically three electrodes will be used. The electrodes may be chlorodized silver electrodes.
  • a bar code 4 is mounted on a bottom portion of the substrate card 1.
  • the electrodes 3 extend through base 5 into chambers 6' and 6' ' in which electrolyte gel 7 is disposed.
  • the chamber is formed in a hollow portion of the body 8 as it is mounted on base 5.
  • the body and the base are sealed together by seal 9 and the base is mechanically bonded to the substrate card 1.
  • a reference junction is provided between chamber 6' and chamber 10.
  • the latter chamber is formed as a hollow region between a cap 11 and the top surface of the body 8.
  • a calibration gel 12 is disposed in chamber 10.
  • a reference junction 13 is disposed to communicate between chamber 6' and chamber 10.
  • an ion selective membrane 14 shown enlarged in Fig. IA communicates between the chamber 10 and the chamber 6''.
  • the bar code includes information describing the characteristics of the associated sensor. In particular, the bar code will identify the calibration value associated with the sensor set at the time the sensor is manufactured. The calibration value is related to the salt concentration of the calibration gel.
  • Fig. 2 illustrates in schematic form the closed loop electrode amplifier circuit for use with the sensor of Fig. 1.
  • this circuit 20 two relay coils are provided to control three switches 21, 22, 23.
  • Switches 21 and 22 are under control of a first relay coil (not shown) while switch 23 is under the control of a second relay coil (not shown) .
  • the sensor under test 24 is shown to have three electrodes, a left electrode L, a center electrode C, and a right electrode R.
  • the right electrode is always connected to the pole designated Measure associated with switch 22 while the center electrode is always conducted to the pole designated MeasureCR associated with switch 23.
  • electrode L when the sensor is positioned on the analyzer, is connected to pole MeasureLR of switch 23.
  • Switch 23 moves between the MeasureCR pole and MeasureLR pole, while remaining connected to the Measure pole of switch 21.
  • Switches 21 and 22 move between the positions Protect and Measure under the control of a single relay such that both switches will either be in the protect mode or in the measure mode at the same time.
  • Pole A of switch 21 is connected to the output of loop integrator U2 which may be a low offset operational amplifier. The output of this amplifier is also connected to an analog to digital converter (not shown) such that digitized signals can be provided to a microcontroller which produces controls for operating the relays.
  • the pole B of switch 22 is connected to the Protect pole of switch 21 and is also connected to the "+" input of sense amplifier Ul providing signal v s ⁇ ns ⁇ along signal line 25.
  • This voltage corresponds to the voltage across resistance R sens ⁇ -
  • the output of the sense amplifier Ul is also provided to an analog to digital converter for transfer to the microcontroller control circuitry.
  • the output of sense amplifier Ul is provided as output V s ⁇ nse and is connected to the "- " input of loop integrator U2.
  • the output of the loop integrator U2 is designated V ⁇ l ⁇ ct .
  • the "+'• input of the loop integrator U2 is connected to a reference voltage supply providing voltage V r ⁇ f .
  • the sense amplifier Ul corresponds to an electrometer operational amplifier.
  • the relays are controlled to isolate the amplifiers from the control electrodes until such time as there has been some dissipation of the static charge.
  • the relays control switches 21 and 22 to be in a Protect mode so that both switches are in contact with the respective protect poles. This protects the amplifiers from the actual process of the generation of static charge. Thus, any negative impact of such a charge generation mechanism is avoided.
  • the analyzer microcontroller then implements a control routine whereby the relay positions are altered with a specific timing and measurements are taken using low bias currents to determine the characteristics of the sensor.
  • a bar code reader reads the assigned characteristics of the sensor from the bar code associated with that sensor and stores that information in a memory associated with the microcontroller. This information is used in calculating calibration compensation.
  • the closed loop amplifier requires only the two amplifiers and the two relays to accomplish the same tasks as an instrumentation amplifier. This offers a savings in printed circuit board area. Furthermore, where resistance measurements may occur at currents higher than 100 pA with an instrumentation amplifier, much smaller currents are utilized in the closed loop amplifier circuitry, thereby avoiding the negative effect which can arise by exposing the electrodes to higher currents over a period of time.
  • the closed loop amplifier can also be made to respond to a self test while it is being protected from static discharge. In its protected state, the electrode is completely disconnected from the amplifier and the loop output V ⁇ l ⁇ ct is basically connected directly to its input v s ⁇ ns ⁇ .
  • a key aspect of the closed loop design is that if any component in the loop fails, the loop integrator will saturate. If the loop integrator, U2 in Fig. 2, is monitored by the microcontroller, then the general health of the loop can be determined by its response to a change in the resistance current input. If the loop response during self test does not correspond to an expected value, it can be deduced that there is a degraded or completely failed component in the loop. A failed component would likely trigger loop saturation while a component degradation would produce a response which differs from the normal response without causing loop saturation. Analyzer software can perform an auto calibration of the gain of the closed loop amplifier. Thus, a gain correction can be made that utilizes the same voltage reference as the microcontroller uses to calibrate out any gain drift or initial error. It is also possible to roughly measure the bias current of the electrometer.
  • the closed loop amplifier capability provides a self test capability that can verify all amplifier components with the exception of the two relays and the actual electrode contacts.
  • the amplifier circuit operation is under the control of a microcontroller.
  • the microcontroller controls the amplifier circuit in accordance with previously stored software programs which cause the microcontroller to produce the necessary control signals for carrying out desired operations with the amplifier circuit.
  • Various software controlled operations and the reasons for carrying out these software operations are described below.
  • the electrical resistance across the entirety of the sensor should be within certain limits. If the resistance is too high, this indicates a broken connection or a defective membrane with insufficient charge carrying ability. If the electrical resistance is too low, this indicates a perforated membrane with no ion selectivity. The voltage output using one of these damaged ISE devices would not reflect the concentration of the selected ion and could lead to an inappropriate medical diagnosis. Furthermore, the electrical resistance between the center electrode and the right electrode must also be between certain limits. Too high a resistance indicates a broken connection whereas too low a resistance would represent a short circuit.
  • An additional feature of the reference electrode resistance is that its value is a function of the salt concentration in its electrolyte gel and in the calibration gel. Since ions can diffuse freely between these two gels, their salt (electrolyte) concentrations will be the same. The concentration of the selected ion in the calibration gel directly determines the calibration "set point" of each individual sensor. This calibration value must be known for accurate readings. The calibration value is provided to the analyzer in the form of the bar code printed on each sensor. By accurate measurement of the right-center RC resistance, any change in the salt concentration of the calibration gel can be detected and compared to that when the sensor was manufactured. Such changes could occur as a result of water loss from the electrode.
  • step 301 the microcontroller sets the amplifier relays to the RL voltage mode. In this mode, switches 21 and 22 are moved to contact the respective Measure poles and switch 23 is moved to contact the pole MeasureLR.
  • step 302 the microcontroller sets a wait period based on a projected settling time for removing transients. In one embodiment, this wait period is set as 19 seconds.
  • the voltage at V ⁇ l ⁇ Ct is then measured four consecutive times as indicated in step 303. An average of these four values is calculated in step 304 and is stored in the microcontroller related memory as V cap . It is noted that a gain of approximately ten is present in this voltage and must be accounted for before using it in a Nernst equation for detecting ion concentration. However, the gain need not be accounted for in the resistance computation.
  • step 305 The amplifier relays are then set to the RL resistance mode in which the relays are placed in the same measuring positions but a resistance measurement is carried out, step 305.
  • step 306 the microcontroller enters a wait mode for settling. This can be 9 seconds. After the wait period has elapsed, the value of the voltage at V ⁇ l ⁇ ct is again measured four consecutive times as indicated in step 307. An average of these four values is calculated in step 308 and stored as Vlcl.
  • step 309 the amplifiers are set for the RC voltage mode whereby the switch 23 is moved to the MeasureCR pole. The device then enters into a wait mode as in step 310, which can be 19 seconds, to allow for settling.
  • the value at V ⁇ l ⁇ ct is measured four consecutive times at step 311 and an average of these four values is calculated and stored as Vrcl in step 312.
  • the amplifier relays remain in the same positions and the RC resistance operation is set in step 313 and the device enters another wait mode 314 to allow for settling. This wait period can be 9 seconds.
  • step 315 the voltage at v ⁇ i ⁇ c i s measured four consecutive times.
  • the average of these four values is calculated at step 316 and stored as Vrc2.
  • the amplifier relays are set into the PROTECT BIT NO. 1 mode where both switches 21 and 22 are moved to be in contact with their Protect poles.
  • the microcontroller compares the values to resistance values that define an acceptable resistance range. If the resistance values are outside of the acceptable range, the sensor must be discarded without being used. Additionally, the resistance value of the RC connection is used as a representation of the ion concentration of the calibration gel. The microcontroller can provide calibration adjustments based on differences between the detected ion concentration and that which it expects to see in view of the information appearing on the sensor bar code.
  • This same calibration process can be carried out using a drift rate threshold algorithm rather than a fixed rate algorithm.
  • the device detects when settling has occurred. Consecutive measurements are made after the device is placed in the appropriate measurement mode and when a difference voltage value between seven of eight consecutive measurements is less than plus or minus 1.00 mV as measured at the A/D input it is detected that the system has undergone settling. This is indicative that the voltage is considered stable. Four consecutive values are then measured and averaged as in the fixed time algorithm. All of the resistance values of interest in the calibration mode may be detected in this manner. The same ultimate calculations for the resistance of RC and LC can then be carried out in the same manner as in the fixed time algorithm.
  • the software in the microcontroller also controls a determination of gel cap removal as well as a determination of the application of a sample to the sensor.
  • the flow chart of Fig. 4 illustrates the steps involved in testing for gel cap removal.
  • the amplifier relays are set to the RC resistance mode in step 401.
  • the value of V ⁇ l ⁇ ct is measured at step 402.
  • the value is compared to a standard value of 1.200 volts in step 403. If the value of V ⁇ l ⁇ ct exceeds 1.200 volts, representing the saturation of the integrator, the cap is detected as being off, step 404.
  • the amplifier relays are then returned to the PROTECT BIT no. 1 mode, step 405. This last step is important because after cap removal, the amplifier inputs are susceptible to electrostatic events should the user touch the electrode top. If V ⁇ l ⁇ ct is not greater than 1.200 volts, steps 402 and 403 are repeated.
  • the algorithm for detecting the presence of a sample is similar to that for detecting removal of the gel cap.
  • the amplifier relays are set to the RC resistance mode in step 501 and the voltage value at v ⁇ i ⁇ c is measured at step 502.
  • the measured voltage value is compared to a standard value of 1.200 volts in step 503. If the voltage value is greater than 1.200 volts, then no sample is present and steps 502 and 503 are repeated. If the measured voltage value is less than 1.200 volts, a sample is present and the device returns to the PROTECT BIT no. 1 mode in step 504. This last step is important because the amplifiers are susceptible to electrostatic discharge events should the user touch the electrode top.
  • step 601 the amplifier relays are set to the LR voltage mode.
  • the device then is placed in a wait mode for 60 seconds to allow for settling with respect to transients in step 602.
  • the voltage value at V ⁇ l ⁇ ct is measured four times consecutively in step 603.
  • the four values are used to calculate the V sol using a simple arithmetic average of the four measured values, step 604.
  • the alternative to the fixed time sample measurement algorithm is a drift rate threshold algorithm.
  • This algorithm is the same as that for the fixed time algorithm except that instead of setting a fixed time for settling of transients, the voltage is measured immediately upon entering the voltage mode and is repeatedly measured until such time as a voltage difference between 7 of 8 consecutive measurements is less than plus or minus 1.00 mV at which point the voltage is considered to be stable. Then, the multiple measurements and average calculations steps can be executed for determining the voltage with the sample present, V sol .
  • Fig. 7 illustrates a table for describing a matrix with respect to the mode of operation and the states of the amplifier relays and the types of measurements to be conducted.
  • the amplifier relays are set to the protect mode so that there is no actual measurement.
  • the switch for controlling either RL or RC connections is set to the RL position and the device is generally set to a resistance measurement mode while no actual measurement is carried out.
  • a PROTECTED BIT no. 2 mode similarly sets the amplifier relays into the protect mode and provides the RL connection as opposed to the RC connection. In this mode, a voltage measurement operation is set, but not carried out due to the status of the amplifier relays.
  • the amplifier relays are placed in the measurement position, switch 23 is set to the MeasureLR pole and the device is placed in a voltage measurement state.
  • the device is the same as in the RL voltage measurement status, except that the switch 23 is now placed into contact with the MeasureRC pole.
  • the device is set in the resistance measurement mode and the amplifier relays are set in the measurement position.
  • the switch 23 is placed in contact with the MeasureLR pole while for the RC measurement the switch contact is placed in contact with the MeasureRC pole. There are two disallowed modes shown in the chart. This indicates that when the amplifier relays are set in the protect mode, the switch 23 cannot be in contact with the center pole C.
  • the center-right (RC) resistance is the resistance of the center wire, the calibration gel, the reference junction, the reference gel and the reference electrode circuit. It must be measured by the analyzer for two purposes, with different specifications. First, there should be a low accuracy measurement with low enough current to permit continuous monitoring for up to five minutes without polarization effects. This is carried out for the detection of the removal of the calibration gel and for the indication of the application of a sample. Additionally, there must be a high accuracy measurement having a better than 10 Koh resolution in 1 to 5 x 10 6 resistance. Current is limited by the polarization limit of the center wire and the reference wire.
  • the center-left (LC) resistance includes wires and gels but is dominated by the membrane resistance. This resistance is measured during development to establish the required amplifier characteristics and to ensure that procedures are available to cast membranes with consistent resistance. In this mode, the current should be minimized to avoid the effects of anomalous conductance mechanisms and intramembrane polarization which might affect subsequent membrane performance.
  • This resistance is also checked by the analyzer during the calibration state to ensure that the membrane has resistance greater than the minimum resistance for an integral, puncture-free membrane. This requires a low accuracy and low current reading. Finally, this resistance is checked by the analyzer after the application of a sample to check that a sample is covering or contacting the membrane. This is also carried out with low accuracy and low current requirements.
  • the resistance of the electrode is known to vary as the magnitude of the electric current applied to it varies, it is important to determine the resistance of the electrode at minimum current levels.
  • a precision, voltage controlled current source in the range of 10 pico amp to 1 na ⁇ o amp is required.
  • the system of the present invention uses a simple control loop that forces the output of amplifier Ul to be equal to the reference input V r ⁇ f to amplifier U2, as shown in Fig. 1.
  • Amplifier Ul measures the voltage across the reference resistor R s ⁇ ns ⁇ *
  • An Y voltage appearing across R s ⁇ nse is t e result of current flowing through that resistor and the electrode under test.
  • the control loop will force a current through R s ⁇ ns ⁇ and the electrode under test to make V s ⁇ n ⁇ equal to V ref .
  • the loop is commanded to make the current through R s ⁇ ns ⁇ equal to zero. That does not exactly happen due to error sources in the amplifiers.
  • the bias currents of amplifier Ul appear to the loop as a current through R s ⁇ ns ⁇ .
  • the loop will produce an equal, but counter current that results in V S ⁇ IJse equal to V r ⁇ f .
  • This current cannot be prevented from flowing through the parallel network formed by R S ⁇ n ⁇ e and the electrode under test.
  • the bias current from amplifier Ul is the minimum current possible in this design. For this reason, amplifier Ul was chosen to be an electrometer amplifier as it has the lowest possible currents, 75 fA.
  • a second error source is the input offset voltage of amplifier 1.
  • Input offset voltage is the amplifier's residual imbalance at its input (that is, zero volts output is produced when the input is equal to its offset voltage) .
  • the loop will force current through R s ⁇ nse until the resulting voltage at the positive input of amplifier 1 produces V S ⁇ nse to be equal to V r ⁇ f . This error can be measured and corrected.
  • V r ⁇ f If V r ⁇ f is adjusted to a value other than zero, the loop will still force V s ⁇ ns ⁇ equal to V r ⁇ f . This will produce a controlled current through R s ⁇ ns ⁇ - That current will be equal to V r ⁇ f /(Kl x R s ⁇ n8 ⁇ ) .
  • a key advantage of this circuit is the ability to change the effective value of R s ⁇ ns ⁇ or (or inversely, V r ⁇ f ) by changing the gain, Kl. If R s ⁇ ns ⁇ and Kl are calibrated and measured in advance, the resistance of the device under test can be determined by measurement of V ⁇ l ⁇ Ct and V r ⁇ f .
  • the effects introduced can be removed by simply measuring the voltage and utilizing that measurement in the calculation of the resistance under test.
  • the gain of amplifier Ul has been optimized to minimize the offset voltage effects from amplifier U2.
  • amplifier Ul becomes the major error source in the system.
  • the effects from amplifier Ul bias currents and offset voltage drive the basic system accuracy.
  • the gain of amplifier Ul is set high enough to make these error sources dominant over the equivalent sources in amplifier U2.
  • An additional benefit of providing amplifier Ul with gain is the scaling effect that it has on the reference input V r ⁇ f and the reference resistor R sense . As the gain is increased, the effect of V r ⁇ f is reduced by an equal amount. This allows precision control of the set current.
  • the parallel resistor-capacitor elements of the electrode can significantly complicate the stability analysis unless a set of simplifying assumptions are adhered to, such as: 1. the dominant pole of the nonelectrode portion of the control loop is always forced to be one decade above or below the high and lowest pole of the electrode (that is, make the loop faster or slower than any response from the electrode. A pole is essentially a low pass filter. The pole frequency is the point at which higher frequency components start to be attenuated.)
  • control loop is constrained to a first order, type 1 system (that is, one loop integrator only) .
  • the circuit design protects the amplifier circuitry from damage due to static which can arise through the multiple insertions and removals of the disposable sensors which are constituted by ion selective electrodes.

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Abstract

Un analyseur est conçu pour recevoir des capteurs à électrode sensible aux ions et à usage unique. Les capteurs sont utilisés pour mesurer des concentrations ioniques dans des échantillons de fluide. L'analyseur comprend des circuits amplificateurs qui sont protégés par des relais afin de prévenir les effets négatifs de décharges statiques qui peuvent résulter de l'introduction et de l'enlèvement répétés des capteurs à usage unique. Un microprocesseur commandé par logiciel commande des algorithmes permettant de détecter l'enlèvement du gel d'étalonnage, l'application d'un échantillon sur le système d'analyse et l'analyse de cet échanitllon.
PCT/US1992/007100 1991-08-27 1992-08-26 Circuits analyseurs servant a analyser des echantillons sur des electrodes sensibles aux ions WO1993004371A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US750,534 1976-12-14
US75053491A 1991-08-27 1991-08-27

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WO1993004371A1 true WO1993004371A1 (fr) 1993-03-04

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PCT/US1992/007100 WO1993004371A1 (fr) 1991-08-27 1992-08-26 Circuits analyseurs servant a analyser des echantillons sur des electrodes sensibles aux ions

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0645626A1 (fr) * 1993-09-21 1995-03-29 Asulab S.A. Dispositif de mesure pour capteurs amovibles
EP1318399A3 (fr) * 2001-12-10 2005-04-20 Lifescan, Inc. Détection passive d'un échantillon pour commencer une analyse
US20090251152A1 (en) * 2006-12-22 2009-10-08 Mettler-Toledo Ag Method and device for monitoring and/or determining the condition of a measuring probe

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2051518A1 (de) * 1970-09-29 1972-04-27 Dahms H Verfahren zum Messen des im Blutserum enthaltenen Chlorids und Bicarbonats
FR2308099A1 (fr) * 1975-04-14 1976-11-12 Technicon Instr Mesure du pourcentage total en volume de particules present dans un echantillon liquide
GB2001443A (en) * 1977-07-22 1979-01-31 Eastman Kodak Co Testing apparatus for analysis of liquid samples
WO1985002257A1 (fr) * 1983-11-10 1985-05-23 Sentech Medical Corporation Analyseur de chimie clinique
EP0306158A2 (fr) * 1987-08-29 1989-03-08 THORN EMI plc Cartouche avec capteur

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2051518A1 (de) * 1970-09-29 1972-04-27 Dahms H Verfahren zum Messen des im Blutserum enthaltenen Chlorids und Bicarbonats
FR2308099A1 (fr) * 1975-04-14 1976-11-12 Technicon Instr Mesure du pourcentage total en volume de particules present dans un echantillon liquide
GB2001443A (en) * 1977-07-22 1979-01-31 Eastman Kodak Co Testing apparatus for analysis of liquid samples
WO1985002257A1 (fr) * 1983-11-10 1985-05-23 Sentech Medical Corporation Analyseur de chimie clinique
EP0306158A2 (fr) * 1987-08-29 1989-03-08 THORN EMI plc Cartouche avec capteur

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0645626A1 (fr) * 1993-09-21 1995-03-29 Asulab S.A. Dispositif de mesure pour capteurs amovibles
FR2710413A1 (fr) * 1993-09-21 1995-03-31 Asulab Sa Dispositif de mesure pour capteurs amovibles.
US5502396A (en) * 1993-09-21 1996-03-26 Asulab S.A. Measuring device with connection for a removable sensor
EP1318399A3 (fr) * 2001-12-10 2005-04-20 Lifescan, Inc. Détection passive d'un échantillon pour commencer une analyse
CN1296704C (zh) * 2001-12-10 2007-01-24 生命扫描有限公司 用于开始测定定时的被动样品检测
US20090251152A1 (en) * 2006-12-22 2009-10-08 Mettler-Toledo Ag Method and device for monitoring and/or determining the condition of a measuring probe

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Publication number Publication date
AU2508292A (en) 1993-03-16

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