Fabrication and Study of On-Chip Electrode for Capacitive Type Uric Acid Sensor

In this paper, a miniaturized biosensor with covalently immobilized uricase enzyme on Polydimethylsiloxane (PDMS) over SiO2/Si substrate is proposed. The PDMS is used as a sensing layer in this work because it is economical, simple to fabricate and an ideal membrane for enzyme immobilization. A PDMS cast with microfluidic channels is bonded with PDMS/SiO2/Si substrate and this aids in realizing a hand-held sensor. The capacitance vs. voltage (C-V) measurement is carried out for the buffered uric acid solution acting as electrolyte over PDMS/SiO2/Si substrate. The C-V characteristics show a linear right shift for increasing concentration of uric acid. The average sensitivity of the sensor for uric acid solutions of the concentration range of 1-9mg/dL is found to be 1.09 mV/mg/dL. The repeatability and stability of the sensor are found to be good.