Integrating An Extended-Gate Field Effect Transistor in Microfluidic Chips for Serum Creatinine Potentiometric Detection

Monitoring creatinine levels in urine helps to recognize kidney dysfunction. In this research we have developed a photocurable membrane for the detection of serum creatinine. Using a system based on field-effect transistors, we carried out comparative tests of creatinine recognition in solutions prepared in different matrices. The device was able to detect creatinine in water, synthetic urine and pH 4 buffer from the lowest concentration tested (3 mmol L-1), covering values between 21 % and 31 % within the range of creatinine variation for healthy individuals (3-27 mmol L-1) with measurement linearity of 97 %. The LOD achieved in the test was 1.31 mmol L-1 under flow conditions. With LOQs between 4.34 mmol L-1 and 24.13 mmol L-1. The system performed very well in the measurements, with hysteresis ranging from 1.1 % to 8.6 % for the different matrices tested. Up to 90 days after manufacture, the sensor still maintained more than 70% of its initial response, even when used periodically during the first week and when stored unused at -18 ºC, it was able to maintain 96.7 % of its initial response. The device used in the flow test only had a useful life of three days due to membrane saturation, which was not reversible. In the interference test, the membrane was also shown to respond to the urea molecule, but in a different response window, which allowed the contributions of the two molecules to be differentiated. EGFETs can be used to identify variations in creatinine concentration and can help in therapeutic decision-making.