A CMOS cantilever-based label-free DNA SoC with improved sensitivity for hepatitis B virus detection

This paper presents a highly-integrated DNA detection SoC, where several kinds of cantilever DNA sensors, a readout circuit, an MCU, voltage regulators, and a wireless transceiver, are integrated monolithically in a 0.35 μm CMOS Bio-MEMS process. The cantilever-based biosensors with embedded piezoresistors aim to transduce DNA hybridization into resistance variation without cumbersome labeling process. To improve detection sensitivity for low DNA concentration use, an oscillator-based self-calibrated readout circuit with high precision is proposed to convert small resistance variation ( of original resistance) of the sensor into adequate frequency variation and further into digital data. Moreover, its wireless capacity enables isolation of the sample solution from electrical wire lines and facilitates data transmission. To demonstrate the effectiveness of full system, it is applied to detect hepatitis B virus (HBV) DNA. The experimental results show that it has the capability to distinguish between one base-pair (1-bp) mismatch DNAs and match DNAs and achieves a limit of detection (LOD) of less than 1 pM.