[Ion Selective sensors for bio measurement]

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Acknowledgement

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

DECLARATION

I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

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Abstract

Recent progress in the design of new polymer membrane-based potentiometric ion-, gas- and bio-selective electrodes in chemistry laboratories at the University of Michigan (Ann Arbor) is reviewed. Emphasis is placed on describing the performance of devices for measuring anions (e.g., salicylate, thiocyanate, chloride and heparin) and gases (e.g., ammonia, carbon dioxide and oxygen) in biological samples, both in vitro and in vivo. Beyond direct measurement of key ions and gases in complex matrices, some of the new membrane electrode systems reported can serve as base transducers for the development of biosensors containing integrated biological reagents, including enzymes and antibodies. New approaches for mass fabricating solid-state ion and biosensor devices as well as future directions for research in the entire field of polymer membrane sensors are also described.

CHAPTER 1: INTRODUCTION6

Research Aims and Objective8

CHAPTER 2: THEORY9

Ion sensitive Field Effect Transistors (ISFETs)9

MOSFET10

ISFET12

Biomedical applications14

Other ISFET applications18

Ion selective sensor21

Principle of Ion-selective Membrane23

CHAPTER 3: STATE OF THE ART SURVEY26

Anion-Selective Electrodes26

Heparin sensor29

CHAPTER 4: DISCUSSION32

Ion-selective Membranes32

Enzymatic Membranes34

Separation Membranes37

New Potentiometric Gas Sensors39

Polymer membrane-based gas sensors40

Differential gas sensors43

Polymer Membrane-Based Biosensors46

Novel polymer membrane materials for ion sensors and biosensors46

CHAPTER 5: SUMMARY AND FUTURE DIRECTIONS50

REFERENCES54

CHAPTER 1: INTRODUCTION

The determination of the ionic constituents (K ÷, Ca 2+, H ÷, CI-,,..) of human electrolytes is very important in both, chronic illness and in acute menacing conditions. Potentiometric methods based on ion-selective electrodes gradually displace optical methods in clinical laboratories , Commercially available ion analysers are highly reliable with a high sample throughput. A disadvantage of such systems is that the analysis is carried out discontinuously, For critical care medicine on-line monitoring of the electrolyte concentration would be preferable. This can be done using an automated in rive system, To place the sensor in rive, a dramatic miniaturisation is required. Several approaches to miniaturise ISE-Sensors are known (micropipette , coated wire type, Capton based , micromachined type and ISFET-type). Small size in rive sensors often show unacceptable drift, which might .be due to the solid state internal contact, loss of membrane ingredients, water absorption or protein glotting.

Accordingly for high precision measurements the sensors must frequently be calibrated [8]. Our goal was to produce a small size potassium selective sensor assays, which can be used in a catheter or with an indwelling cannula. Miniaturisation of the system is realised using silicon technology. The potassium concentration is measured potentiometrically using an ion selective polymer membrane in combination with an Ag/AgCl/ p-HEMA reference electrode integrated on the same chip. To overcome problems resulting from a long time contact of the sensor with protein-containing sample solution, an ...