Towards a biohybrid sensing platform built on impedance-based bacterial flagellar motor tachometry


Though the chemotaxis sensing system of Escherichia coli is known to approach fundamental biosensing limits, few attempts have been made to co-opt it as the front end for a biohybrid sensor. We propose a biohybrid sensor that electrochemically monitors chemotactic bacterial flagellar motor (BFM) rotation speed and direction to infer analyte concentration for a low-power, fast, and sensitive response. We first present the design and fabrication of a four point impedimetric array that uses current injection electrodes to circumvent electrode polarization screening, enabling solution resistance monitoring within a four-micron by four-micron region. We then demonstrate the first lithographically patterned silica shaft encoders for the BFM, which utilize localized biotin-avidin chemistry to selectively bind to the BFM and encode rotation. When these two components are integrated by bringing the rotating encoders in proximity with the microelectrodes, they will comprise an electrochemical method for observing the BFM. Such an impedance-based biohybrid sensor obviates the need for a microscope and in principle may be multiplexed and scaled to large arrays of bacterial cells, enabling the development of deployable low-power and fast sensing systems that directly observe the BFM to infer analyte concentration.

Proceedings of IEEE Biomedical Circuits and Systems Conference