The prototype of creatinine sensor using differential extended-gate FETs was fabricated for the application of continuously measurement in point-of-care diagnosis of chronic kidney disease. The voltage drift of this sensor caused by temperature changes in the test solution and by fluorescent light irradiation was significantly reduced by introducing a differential circuit. The sensor showed a reversible voltage response to increases or decreases in creatinine concentration in phosphate buffer solution. The detectable range of creatinine concentration is 0.01 - 0.3 mg/mL, covering the high end of the serum creatinine concentration range in healthy adults to the threshold for starting dialysis.
