DEVELOPMENT OF AN INTEGRATED THERMAL BIOSENSOR FOR THE SIMULTANEOUS DETERMINATION OF MULTIPLE ANALYTES

A flow injection thermal microbiosensor was designed for the simultane ous determination of multiple analytes. The biosensor consisted of fiv e thin-film thermistors which were located along a single microchannel . The device was fabricated on a quartz chip by micromachining. The fe asibility of employing this system for the detection of two independen t enzyme reactions was demonstrated using two different pairs of enzym es, urease-penicillinase and urease-glucose oxidase. The enzymes were immobilized on agarose beads, which were then sequentially packed into distinct regions of the microchannel, Using this method, samples cont aining urea mi?red with penicillin V or with glucose were simultaneous ly analysed, Linear ranges of up to 20 mmol l(-1) urea, 40 mmol l(-1) penicillin V and 8 mmol l(-1) glucose (saturated with O-2) were obtain ed using a flow rate of 30 mu l min(-1) and a sample volume of 20 mu l . The relative standard deviations for urea and penicillin V assays we re 1.13 and 2.42% for the first 100 samples and 1.17 and 2.78% for 200 samples, respectively. The sensor is capable of analysing 25 samples per hour.