Geometry-assisted dielectrophoretic localization on a CMOS sensor array for label-free detection of viable Escherichia coli.

Authors

Siyao Chen, Yoshihisa Yamashige, Naoshi Kondo, Yuichi Ogawa, Keiichiro Shiraga

Published in

The Analyst. Aug 06, 2026. Epub Aug 06, 2026.

Abstract

Rapid and sensitive detection of viable bacteria is essential in food safety, healthcare, and environmental monitoring. Although label-free electrical biosensing offers a rapid and simplified alternative to conventional methods, its performance is often constrained by inefficient transport and accumulation of target cells at the sensing interface. Here, we present a microfluidic geometry-assisted dielectrophoretic (DEP) enrichment strategy integrated with a 65 GHz LC-oscillator dielectric sensing platform for label-free detection of Escherichia coli. A Y-shaped microfluidic architecture coupled with a high-density DEP electrode array (62 × 24, 3 × 3 mm²) enables spatial redistribution of bacteria from a wide upstream region into a confined downstream detection channel. This geometry-induced concentration enhances the effective local cell density per sensing element, thereby amplifying the initial sensing response under the same DEP operating conditions. Under optimized conditions (500 kHz, 0.01 S m^-1), distinct DEP behaviors of live, pasteurized, and autoclaved cells enable preferential enrichment of viable bacteria. Compared with a straight-channel configuration, the proposed design achieves a 20-fold enhancement in sensitivity, with a detection limit of 4.4 × 10³ CFU mL^-1 within 20 min, further improved to 8.8 × 10² CFU mL^-1 with extended enrichment. Unlike systems that use the same electrodes for DEP manipulation and impedance sensing, this platform separates the two electrical functions into co-located DEP and LC sensing units. It enables localized, per-element frequency-shift mapping of geometry-enhanced bacterial accumulation within the CMOS array.

PMID:
42560296
Bibliographic data and abstract were imported from PubMed on 06 Aug 2026.

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