ISFET GLUCOSE SENSOR FOR UNDILUTED SERUM SAMPLE MEASUREMENT

A glucose sensor composed of an ion-sensitive field-effect transistor (ISFET), an enzyme-immobilized membrane and an external membrane is proposed. The external membrane, which is albumin highly crosslinked by glutaraldehyde, restricts glucose diffusion to expand the measuring range and make a stable response in a low buffer-capacity solution. The glucose concentration in a serum sample is measured using this sensor without dilution by the buffer solution; the sensor outputs show a good linear relationship with up to 300 mg/dl glucose concentration.