Microbiosensors for Clinical and Process Analysis

Abstract

Microbiosensors for urea and adenosine triphosphate (ATP) are prepared with ion sensitive field effect transistor (ISFET) modified by enzymes such as urease and H ⁺-ATPase respectively. The Micro-urea sensor gives a linear relationship between the initial rate of the output gate voltage change and the logarithmic value of urea concentration between 16.7 and 167 mM. Determination of urea is possible within 30 s. The optimum pH is 6.0–6.5, at 37 °C. The system can be used for 20 d with only slight loss of enzymatic activity. The micro-ATP sensor can be used for the ATP determination. A linear relationship was obtained between the initial rate of change of the differential gate output voltage and the logarithm of the ATP concentration over the range 0.2–1.0 mM ATP-sensing system exhibited a response to 1 mM ATP for at least 18 d.