Solid state potentiometric sensor for the estimation of tributyrin and urea

We report fabrication of a potentiometric biosensor on silicon for the estimation of tributyrin and urea based on enzymatic reactions. The sensor is an electrolyte-insulator-semiconductor capacitor (EISCAP) that shows a shift in the measured C-V with changes in the pH of the electrolyte. This pH shift can be induced by the enzyme-mediated hydrolysis of tributyrin and urea which results in acidic and basic solutions, respectively and an EISCAP can be effectively used for the detection of these bioanalytes. A silicon nitride based EISCAP was used for the first time to detect triglycerides and urea. The sensor was able to detect millimolar concentrations of the bioanalytes (tributyrin/urea). The most important features of the tributyrin and urea sensor are high sensitivity, long life-time, easily built at a low cost, micro-construction and short response time. Optimization of the conditions for the enzymatic reaction and calibration of the sensor are included.