A NEMS-Array Control IC for Subattogram Mass Sensing Applications in 28 nm CMOS Technology

The miniaturization and cost reduction of a gas chromatograph is addressed in this paper, leveraging on nanoelectromechanical systems (NEMS) detectors and a mixed-signal integrated circuit. The instrument and chip architectures are thoroughly described, characterized, and compared to other approaches like thermal conductivity detectors (TCDs). The 28 nm CMOS circuit addresses the sequential and parallel driving and readout of NEMS arrays with resonance modes in the 10 MHz to 1 GHz range. It integrates an analog-to-digital converter (ADC), two digital-to-analog converters (DACs), and 4 tone DSP [lock-in amplifier (LIA) and direct digital synthesizer (DDS)] for increased throughput. Its area is 0.9 mm
²
and it draws 68 mW of power compared to 10 cm
²
and 3 W in previous discrete implementations. Lab and field characterizations show that the combined NEMS and IC can provide down to 10 ppb limits of detection (LOD) on selected gas species.