Development of an EGFET Microsensor with 3D Structure for High-Specificity Cardiac Troponin I Detection

In this study, we used microelectromechanical systems (MEMS) technology to design a three-dimensional microsensor, which is based on an extended gate field-effect transistor (EGFET), to detect cardiac troponin (cTnI). A planar micro-reference electrode was integrated onto the same chip. All fabrication processes were compatible with integrated circuit and MEMS technologies, and the dimension of our cTnI microsensor was 1.0 cm × 0.8 cm. From measurements, microsensor sensitivity was 11.408 V (ng ml −1 ) −1 and sensing linearity was 0.961 in the 0–0.05 ng ml −1 range. In the 0.05–1 ng ml −1 range, sensitivity was 0.887 V (ng ml −1 ) −1 and linearity 0.933. The detection limit was 0.0063 ng ml −1 , and the response time was approximately 300 s. Bridge-type source read-out, temperature correction and temperature compensation circuits were also successfully designed and were used to reduce the influence of temperature on sensing signals.