Sensor device

Details Sensor device Sensor device

1996-10-16

1999-05-25

Dung, T.

Chemistry: electrical and wave energy

Apparatus

Electrolytic

204403, 204416, 204418, 205778, 205779, 2057815, 2057825, 205787, 205789, G01N 27404

Patent

active

059067195

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to sensor devices such as are used in the determination of a component or components which may be present in a fluid sample such as a physiological fluid (e.g. blood, urine) or an effluent.
PCT Application No. PCT/GB92/00443 (Publication No. WO-A-92/16647) discloses a sensor device which is suitable for detecting a targeted lipophilic component present in a fluid sample and providing an output representative of the content of the component in the sample. This device incorporates a permselective membrane which is substantially impermeable to charged non-lipophilic species that may be present in samples to be analysed and being selective, by partitioning, for lipophilic species. As a result, a preselected lipophilic component in the sample partitions into and diffuses through the barrier for detection on the other side thereof.
In preferred embodiments of the aforesaid PCT application the membrane is of PVC incorporating a plasticiser (which acts as a permselective medium) such as dioctylphthalate or iso-propyl myristate. Such membranes are preferably used in an amperometric sensor incorporating an electrochemical detection arrangement comprising an electrode system and a liquid or gel phase electrolyte medium which is interposed between the membrane and the electrodes. The electrode system may comprise a working electrode and a reference (or pseudo reference) electrode. The electrolyte medium provides a charge carrier system which ensures that a current may flow between the electrodes.
Whilst giving satisfactory results, the use of the electrolyte medium (which is usually, but not necessarily, aqueous) does however present a number of disadvantages. In particular it complicates cell construction and is not particularly suitable for use in dry reagent strip format sensors.
It is therefore an object of the present invention to obviate or mitigate the abovementioned disadvantages.
According to the present invention there is provided a sensor device for detecting a predetermined component present in a fluid sample and providing an output representative thereof, the device comprising a permselective membrane incorporating a charged organic species, said permselective membrane being at least partially impermeable to charged substantially non-lipophilic species that may be present in the sample, and an electrode arrangement in intimate contact with the membrane but not exposed at the side thereof to be presented to the fluid sample.
Therefore in accordance with the invention the permselective membrane incorporates a charged organic species (which may function as a charge carrier) and as such it is possible for the electrode arrangement to be in intimate contact with the membrane. The membrane therefore, combines both the functions of supporting electrolyte and permselective barrier. The need to provide a separate liquid or gel phase electrolyte medium between the electrodes and the membrane is thus avoided. This provides significant advantages including the possibility of highly simplified cell construction with no liquid reagents, such constructions being suitable in principle for dry reagent strip format sensors.
A further advantage associated with the use of the charged organic species is that organic phase electrochemistry can be exploited allowing a wider voltage range to be applied than can be used with aqueous electrolyte layers (due to the break down of water at high voltages).
The electrode arrangement may be in intimate contact with the face of the membrane opposite to that face which is presented to the sample. Alternatively the necessary intimate contact may be achieved by virtue of the electrodes being incorporated within the membrane without being exposed to the sample.
Sensor devices in accordance with the invention are preferably non-potentiometric devices. Most preferably the sensor devices are amperometric devices in which the electrode system comprises a working electrode and a reference or pseudo-reference electrode system. In operation of such devices, the working

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I.M. Christie, P.H., Treloar and P. Vadgama, "Platicized poly(vinyl chloride) as a a permselective barrier membrane for high-selectively amperometric sensors and biosensors", Analytica Chimica Acta, vol. 269, 1992 month unavailable.

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