摘要
The charge carried by biomolecules immobilized on the electrode surface causes a direct change in the electrode capacitance, enabling capacitive sensors to provide label-free real-time biodetection for point-of-care diagnostic applications. Capacitive sensors are easier to design and implement than other FET (field effect transistor)-based label-free biosensing devices. This work presents a 16 &null 16 capacitive sensor array implemented in a 0.35-&null CMOS (complementary metal oxide semiconductor) process. The signal-to-noise ratio of on-chip switched-capacitor readout benefits from the reduced parasitic capacitance through monolithic integration. The interdigitated sensing electrodes have an area of 30 &null 30 &null <sup>2</sup> and a measured capacitance of 57.3 fF in air. The pH measurement exhibited a capacitive sensitivity of 151 fF/pH. The DNA (deoxyribonucleic acid) measurements showed a capacitive sensitivity of 94 fF/log<sub>10</sub>[DNA] from 10 aM to 100 pM at a clock frequency of 2 MHz.