Electrolyte Insulator Semiconductor Capacitor (EISCAP) Biosensor

Electrolyte Insulator Semiconductor capacitors (EISCAPs) are sensitive to changes in the pH of the electrolyte which can be sensed as shifts in the capacitance–voltage characteristics of the device. The sensitivity to pH can be utilized for biosensing as the enzymatic hydrolysis of many bioanalytes produce acids and bases, changing the pH. The EISCAP is optimized for the detection of triglycerides with the enzyme lipase and urea with the enzyme urease. Good agreement was found between the measurements with the EISCAP and clinical measurements. The EISCAP was miniaturized using micromachining techniques. With the enzyme immobilized on the Insulator surface, a compact biosensor chip was fabricated and characterized.