Ultra sensitive CMOS biosensor array for label free DNA detection: Circuit design consideration

Electrical biosensors are one strategy being explored for the development of a rapid point-of-care and onsite DNA testing tools since this technology is amenable to miniaturization, can be accurate and highly sensitive with simple instrumentation, and relatively inexpensive. A label free and fully integrated semiconductor sensor array based on differential charge-based capacitance measurement for DNA sensing is presented. The 4 × 4 sensor array circuit has been designed using a 2-poly 2-metal 1.2 μm CMOS process from ON Semiconductor. Each sensor features an integrated microelectrode of 16 μm². The linear sensitivity is 3 mV/fF for the target input capacitance range of 1 to 10³ fF. An array-clock controller scheme to selectively activate the array cell and capacitance-to-voltage conversion circuit has been proposed, enabling low power biosensor arrays.