A Dual-Sensing CMOS Array for Combined Impedance-pH Detection of DNA with Integrated Electric Field Manipulation

We have developed a CMOS System-on-Chip capable of concurrent DNA detection and actuation towards ultrafast and accurate molecular diagnostics. The system relies on a sensor array to perform electrochemical imaging by combining potentiometric ion-sensitive field-effect transistor (ISFET) sensing with impedance spectroscopy to concurrently detect DNA molecules and protons generated during an amplification reaction at high resolution. The impedance sensing electrodes are also used to conduct DNA manipulation using dielectrophoresis (DEP), further improving performance. The system achieves a maximum electric field strength of 2.5MV/m, generated with an AC voltage input of 1.8V, which is suitable for a battery supplied portable device. The sensing system made of EIS and ISFET front-ends are implemented in 0.18 μm CMOS technology. The ISFET sensing system presents a readout sensitivity of up to 129 mV (with a gain of 15 dB) with programmable controlled gate voltage to compensate non-idealities. Lastly, the EIS system is able to detect an impedance up to 100 MO within a frequency range between 100Hz-100kHz, presenting a dynamic range of 84.1 dB. The integrated systems achieve dual sensing and actuation for electrochemical DNA sensing with improved performance.