A fully integrated wireless CMOS microcantilever lab chip for detection of DNA from Hepatitis B virus (HBV)

In this work, a fully integrated DNA detection system-on-a-chip (SoC) was implemented by 0.35 μm commercialized standard CMOS process for label-free and real-time detection of Hepatitis B virus (HBV) DNA. The chip implementation was achieved in the Taiwan Semiconductor Manufacturing Companyʹs (TSMC) 0.35 μm CMOS process. The implemented chip size was 6 mm by 5 mm. It included microcantilever DNA sensors, readout circuits, a microcontroller unit (MCU), and an on-off key (OOK) wireless transceiver (TX/RX). The DNA sensing device, based on piezoresistive type microcantilever, was achieved by post processes after the standard CMOS circuit fabrication. The post processes included Au deposition to enhance its biocompatibility and reactive ion etching (RIE) to release the miscrocentilever. To evaluate the sensing device, the 19-mer nucleotide probe DNA of HBV conservative sequence was modified with thiol group to cross link onto the Au layer. To enhance the performance of the integrated SoC, furthermore, the oscillator-based self-calibrated readout circuit was designed and implemented. In addition, the wireless capability was accomplished by the OOK TX/RX. The experimental result revealed that the DNA detection SoC has good selectivity between one base-pair mismatched DNA and all matched DNA. This DNA SoC demonstrated the sensing limitation of 1 pM in the label-free DNA detection.