Oscillator-Based Electrochemical Capacitance Imager with Frequency-Division-Multiplexed Readout
Abstract
Electrochemical biosensors, built using complimentary-metal-oxide semiconductor (CMOS)
technology, have shown promise for various applications in health-care diagnostics, disease
detection, and life science research. Unlike traditional bench-top instrumentation, CMOS-based platforms offer large-scale integration of sensor pixel arrays and readout electronics
on the same chip, yielding improved spatial resolution, throughput, and signal-to-noise
ratio (SNR) compared to non-integrated systems.
In this thesis, we present the design and electronic characterization of a CMOS oscillator-
based electrochemical capacitance imager for biosensing. The imager features both time-
division multiplexed (TDM) and frequency-division-multiplexed (FDM) readout, and is
suitable for overcoming Debye-length-screening effects in integrated electrochemical biosensors. The implementation of FDM readout enables improved frame rate or improved signal-to-noise ratio (SNR) when compared to an imager that employs standard TDM readout.
Each pixel in the array contains a 5-MHz–180-MHz capacitance-to-frequency converter
(CFC) to detect changes in the interfacial capacitance at an in-pixel working electrode,
ranging in area from 2×2-µm 2 to 200×200-µm 2.
We report experimental results from electronic characterization of a 420-pixel, 3.0×2.5
mm 2 capacitance imager, fabricated in a 1.8-V, 0.18-µm mixed-signal CMOS process. To
the best of our knowledge, our work is the first demonstration of a CFC-based CMOS
capacitance imager for biosensing with both TDM and FDM readout.
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Cite this version of the work
Ashwin Krishnan
(2022).
Oscillator-Based Electrochemical Capacitance Imager with Frequency-Division-Multiplexed Readout. UWSpace.
http://hdl.handle.net/10012/18083
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