AU5495099A

AU5495099A - Accessory for measuring or dosing, in particular electrochemical measurement sensor

Info

Publication number: AU5495099A
Application number: AU54950/99A
Authority: AU
Inventors: Jeam-Jacques Pauzon
Original assignee: Radiometer Analytical SAS
Current assignee: Radiometer Analytical SAS
Priority date: 1998-10-15
Filing date: 1999-10-15
Publication date: 2000-04-20
Also published as: FR2784606B1; EP0994350A1; FR2784606A1

Description

r/U.U II 2 Reguladon 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: ACCESSORY FOR MEASURING OR DOSING, IN PARTICULAR ELECTROCHEMICAL MEASUREMENT SENSOR The following statement Is a full description of this Invention, Including the best method of performing It known to Background of the invention: The present invention relates, in a general manner, to the field of measurement and dosing, and its subject is, more particularly, an accessory for chemical or electrochemical measuring or dosing, such as in particular (but not exclusively) an electrochemical measurement sensor.

Description of the prior art An electrochemical measurement set-up (or chain or system) for example for measuring the pH of a medium, comprises three main elements, as illustrated in Figure 1 of the appended schematic drawing: an electrochemical measurement sensor 1, placed in contact with the medium 2 contained in a measurement vessel 3; a measurement converter 4, connected up in the course of a measurement by an electrical link 5 to the electrochemical measurement sensor 1, and comprising means 6 for displaying the measured electrochemical parameter, such as the pH of the medium 2; calibration solutions 7, of precise and known characteristics, serving as references.

The measurement converter 4 calculates the value of the electrochemical parameter to be measured, by applying an appropriate algorithm to the value of 20 the electrical signal sent by the sensor 1, an transmitted on the link 5. This algorithm uses a series of parameters characteristic to the sensor 1, the socalled calibration parameters. These parameters are obtained during calibration, by immersing the sensor 1 in one, two or more calibration solutions 7, depending on the type of electrochemical measurement performed.

25 The diagram given by Figure 1 applies in particular to the following electrochemical measurements; -pH measurement: the sensor 1 consists of a pH-sensitive glass membrane electrode combined with a reference electrode which, for its part, is pH-sensitive. This type of sensor requires relatively frequent calibrations, especially if the measurements are carried out in difficult media, leading to rapid contamination; Ion measurements: various selective electrodes, sensitive to types of ions other than H+ are also used in a similar manner to the pH-sensitive electrode mentioned above. These electrodes must be calibrated with the aid of several calibration solutions.

Conductivity measurements: the electrical conductivity of the medium, in general a solution, is determined by measuring the electrical resistance between two metal electrodes immersed in this solution. A particular technique, using four electrodes, makes it possible, under certain conditions, to obtain more accurate results. Regardless of the type of sensor (with two, three or four electrodes), it must be calibrated with the aid of a calibration solution, so as to determine the constant which makes it possible to convert the measured resistance value into a conductivity value.

Mention may also be made of sensors whose operating principle is based on the utilization of current/voltage/time relationships, at the interface between a conducting or semiconducting constituent material of the sensor, and the measurement solution. Numerous biosensors are designed according to this principle.

In all cases, the calibration parameters are presently stored in the electronic memory of the measurement converter 4. Consequently, once the sensor 1 is separated from the measurement converter 4 with which it has been calibrated, this sensor becomes unusable, and the use of another converter involves a new calibration. This, in practice, it is not possible either to detach a sensor from its measurement converter, or to substitute one sensor for another on a given converter. Therefore, the present-day systems, as recalled above possess very limited flexibility.

*25 Summary of the invention The aim of the present invention is to avoid these drawbacks, by providing an electrochemical measurement sensor, or other similar accessories for ooo* measuring or dosing, which is enhanced in such a way as to no longer be necessarily tied solely to the measurement converter used for its calibration, and which can therefore be used also with another appropriate converter.

For this purpose, the subject of the invention is essentially an accessory for chemical or electrochemical measurement or dosing, which comprises an "electronic tag" containing in its memory characteristic calibration parameters for this accessory, the contents of this memory being interrogable without contact, via radio link, from a measurement converter or other controller with a built-in transmitter.

Such an accessory is in particular an electrochemical measurement sensor, in which case, in accordance with the invention, the electronic tag is built into or attached to the body of the electrochemical measurement sensor and contains, in its memory, the calibration parameters for this electrochemical measurement sensor.

Thus, the inventive idea consists in associating, with the sensor itself, an electronic memory of sufficient size to contain the calibration parameters for the sensor, access to this memory being possible on the basis of a measurement converter equipped with a transmitter. Once the calibration has been performed, the measurement converter used will be able to write the calibration parameters into the memory of the sensor. Thereafter, measurements may be performed with this sensor, using any other converter capable of "reading" the calibration parameters in the memory of the sensor. Said sensor is therefore no longer tied solely to the converter used for its calibration.

As will be readily understood, the invention achieves great flexibility, 20 whilst guaranteeing the accuracy of the measurements since each converter is S adapted to the calibration parameters which can vary from one sensor to another. Moreover, the design, which is the subject of the invention, makes it possible to create novel adapted products, comprising: more or less automated calibration stations, carrying out the calibration 25 of the sensors and loading their characteristic parameters into their memory; measurement converters, using the values of the calibration parameters contained in the memory of the sensor employed, and establishing the value of the parameter measured with the aid of this sensor on a solution, or other sample.

These two functions may be grouped together on a single instrument.

The implementation of the invention involves the use of electronic tags, these being components which are presently being increasingly used in the fields of sale and the protection of goods (as an antitheft device), of access control, etc. These devices, which are commonly designated by the initials RFID (standing for the expression "Radio Frequency IDentifier"), allow the detection and identification of an object, at greater or lesser distance and without mechanical or electrical contact, with the aid of a simple radio link. Figure 2 shows diagrammatically the principle of such an electronic tag designated overall by the label 8, which comprises in particular a memory 9, as well as an aerial 10. This electronic tag 8 is used in combination with a transmitter 11, itself also provided with an aerial 12, the bidirectional radio link set up between the electronic tag 8 and the transmitter 11 being symbolized at 13 by a doubleheaded arrow. More particularly, there now exist so-called passive electronic tags for which the energy of the radio wave originating from the transmitter 11 is sufficient to power the tag 8 electrically, thereby doing away with the need for any specific energy source for this tag. Rewritable electronic tags are also available; for example, read/write electronic tags, with a memory capacity of 2 kilobits on an area of 1 cm 2 are presently available, at modest cost.

The inventive idea, applied to an electrochemical measurement sensor, therefore consists in building into or attaching to the body of such a sensor an electronic tag of the kind explained above, which will thus constitute the sensor 20 memory in which calibration parameters of the sensor may be stored. Once calibrated, this sensor can be used with any measurement converter capable of S "reading" the contents of the electronic tag, thus signifying that an appropriate transmitter is built into the measurement converter.

In view of its capacity, the memory of the electronic tag can contain, in •25 addition to the measurement sensor calibration parameters, other information such as: production parameters, check parameters, calibration log, etc., which characterize the "life" of the sensor.

The production parameters may in particular be: the type of sensor, the batch number, the date of manufacture.

The control parameters are, for example: the slope and the ordinate at the origin (in the case of a sensor with a linear-response electrode), the reference potential, the date of the next control.

The storing of the calibration background consists in keeping the record of the last calibrations (the number depending on the memory capacity available for this function), this record comprising: slope, ordinate at the origin, response time, calibration date, scheduled date for the next calibration. On the basis of these data, the measurement converter will be able to calculate the optimal date for the next calibration, or else recommend a maintenance service, or else the replacement of the sensor.

Given the customary use of calibration solutions, as explained earlier with reference to Figure 1, the invention is also advantageously applicable to a measurement accessory consisting of a calibration solution contained in a vessel, in which case the electronic tag is built into or attached to the vessel and contains, in its memory, information, such as: production parameters: type, batch number, date of manufacture; traceability data: identification of the primary standard solution; control parameters: exact value and uncertainty level, expiry date; logbook: date of first use, usage dates.

Thus "tagged", the calibration solution can be used in association with an electrochemical measurement sensor equipped with an electronic tag, such as defined above, and with a measurement converter incorporating a transmitter able to "interrogate" both the measurement sensor and the calibration solution.

oo i In this way, a complete and consistent electrochemical measurement system is obtained which is very reliable and which notably improves metrology aspects: the calibration operations can be completely automated, in the most advanced versions of the system. In simpler versions, the operator can be guided step by step through a sequence of simple manual actions, whilst all the data transfers are carried out automatically.

The use of the electronic tag affords a significant improvement in the o. reliability of the measurements, by assisting the user in the application of the rules of "Good Laboratory Practice". In particular, because the electrochemical measurement sensor keeps all its parameters in its memory, the risk of error due to erroneous calibration of the measurement converter is eliminated.

Moreover, in a general manner, the data contained in the electronic tags 6 of the sensor and of the calibration solution constitute very reliable records for printing measurement reports.

The extension of the use of electronic tagging to the operators and the samples of analytes provides a fully reliable acquisition of all data elements required to comply with the Good Laboratory Practice (GLP) standards. Results are automatically and reliably linked to: sample, operator, sensor, calibration date, calibration operator, calibration solutions.

Brief description of the drawings The invention will in any event be better understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of examples, accessories for the measuring or dosing in accordance with the invention, used in various applications: Figure 1 (already mentioned) represents, basically, a conventional electrochemical measurement chain; Figure 2 (already mentioned) is a basic diagram of an electronic tag associated with a transmitter and usable within the context of the present invention; Figure 3 is a basic diagram of an electrochemical measurement system using a measurement sensor and calibration solutions with electronic tags; 20 Figure 4 is a basic diagram of an electrochemical measurement system stemming from that of Figure 3, but incorporating complementary elements; Figure 5 illustrates, diagrammatically, another application of the present invention.

S* In Figure 3, which represents an electrochemical measurement system in S 25 accordance with the invention, the elements common to those of Figures 1 and 2 S (described earlier) are designated by the same numerical labels. This system also comprises, in a general manner, an electrochemical measurement sensor 1, a measurement converter 4 and at least one calibration solution 7.

According to the invention, an electronic tag 8 is built into the body of the electrochemical measurement sensor 1, the electronic tag 8 containing in particular, in its memory, the calibration parameters for this sensor 1.

Incorporated into the measurement converter 4 is a transmitter 11, equipped with an aerial 12, which communicates via a bidirectional radio link 13 with the electronic tag 8, in such a way as to "interrogate" the sensor 1 and to "read" its calibration parameters, when carrying out a measurement, for example the measurement of the pH of a medium 2 contained in a measurement vessel 3.

For the requirements of the drawing, the antenna 12 has been represented outside the casing of the measurement converter 4, but in practice, given the small transmission distance (not exceeding 10 to 20 cm), this antenna 12 could easily be built into, for example, the front face of the casing of the converter 4.

The or each calibration solution 7 comprises, for its part also, an electronic tag 8' built into the vessel containing this solution. During the use of a calibration solution 7, the transmitter 11 of the measurement converter 4 "reads" the data contained in the memory of the electronic tag via a radio link 13'.

As illustrated in Figure 4, the electrochemical measurement system described earlier can again incorporate the product samples to be analyzed and/or the operator or operators involved during the measurement. Stated otherwise, electronic tags 18 are associated with the product samples to be analyzed, such as the medium 2 contained in the vessel 3, and other electronic tags 19 are again carried by each operator 20. Like the previous ones, these additional electronic tags communicate, via radio links symbolized at 21 and at 22 respectively, with the measurement converter 4 incorporating a transmitter.

The set of information thus acquired from the various electronic tags 8, 8', 18, 19 makes it possible to feed a database, in a totally reliable manner. In particular, the contents of this database satisfy the traceability-of-results 25 requirements defined by the rules of "Good Laboratory Practice", making it possible to reply at any time to the following questions: which measurement result, for which sample, by which operator and with which electrode sensor, calibrated under which conditions etc.

As illustrated by Figure 5, the invention is again applicable to an accessory of the dosing syringe 14 kind, also referred to as a "burette", which allows the accurate dosing of a volume of reagent. Such a syringe comprises a cylindrical body 15 whose inside diameter is known with low uncertainty, and an electromechanical device with controller 16, which makes it possible to translate a piston 17 in the body 15 with great accuracy. These syringes are used with socalled "titrators", which receive interchangeable syringes, so as to allow simple and rapid reagent changing. This raises a problem which is entirely similar to that encountered in respect to electrochemical measurement sensors, and which can be solved in an identical manner, by building into or attaching to the body of the dosing syringe 14 an electronic tag shown in Figure 4. Stored in the memory of the electronic tag 8" are the calibration data for this dosing syringe 14, taking into account the particular features of the profile of the dosing syringe 14. The controller 16 incorporates a transmitter 11, with aerial 12, which communicates via radio link 13 with the electronic tag and thus makes it possible to store, in the microprocessor of this controller 16, the calibration data specific to each syringe 14 used, so as to drive the movement of the piston 17, thereby achieving improved accuracy.

Description of the preferred embodiments It is evident that the invention is not limited solely to the embodiments described hereinabove by way of examples; on the contrary it embraces all e variant embodiments and variant applications complying with the same principle. In particular, one would not be parting from the context of the invention: by applying the latter to measurement sensors other than electrochemical sensors, which also require calibration, or again to other accessories for measuring or dosing; by attaching the electronic tag by any means to the accessory

S

25 concerned, this tag not necessarily being built into the body of said accessory; by storing all complementary data in the memory of the electronic tag, according to the nature of the accessory concerned, and as a function of the capacity of this memory.

Claims

1. An. accessory for chemical or electrochemical measurement or dosing, which comprises an "electronic tag" containing in its memory characteristic calibration parameters for this accessory, the contents of this memory being interrogable without contact, via radio link, from a measurement converter, or other controller with a built-in transmitter.

2. The accessory as claimed in claim 1, this accessory being an electrochemical measurement sensor, the electronic tag being built-in or attached to the body of the electrochemical measurement sensor and containing, in its memory, the calibration parameters for this electrochemical measurement sensor.

3. An electrochemical measurement sensor as claimed in claim 2, wherein the electronic tag of this sensor contains in its memory, in addition to the calibration parameters, other information chosen from: production parameters, control parameters, calibration background of the sensor.

4. The accessory as claimed in claim 1, this accessory being a calibration solution contained in a vessel, the electronic tag being built-in or attached to the vessel and containing, in its memory, information relating to the calibration S solution, such as production parameters, traceability data, control parameters, logbook, a calibration solution being usable in particular in association with an •5 electrochemical measurement sensor as claimed in claim 2 or 3. An electrochemical measurement system, which comprises an electrochemical measurement sensor as claimed in claim 1 or 2, at least one calibration solution as claimed in claim 4, and a measurement converter with S transmitter communicating via radio link, with the electronic tags of the sensor and of the of each calibration solution.

6. The electrochemical measurement system as claimed in claim 5, which furthermore comprises electronic tags associated with the samples to be analyzed and/or with the operators, these electronic tags communicating also, via radio link, with the measurement converter.

7. The accessory as claimed in claim 1, this accessory being a dosing syringe, the electronic tag built-in or attached to the dosing syringe containing in its memory the calibration data for this dosing syringe, taking into account the particular features of the profile of said dosing syringe. DATED this 15th day of October 1999. RADIOMETER ANALYTICAL S.A. WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA S