A micro sensing probe for detecting individual biological cells

While detecting individual biological cells is essential in cytometry for counting cells and analyzing the cellular contents, miniaturized cell-detecting devices are desirable not only for on-site biomedical analysis but also for in situ monitoring of cell dynamics. To study the electrical detection mechanism, a micro sensing probe has been developed on silicon wafers using microfabrication technology. The device consists of an array of through-holes in diameter of 20, 60, and 100 μm, with gating electrodes around the holes for cell sensing. An interfacing system including demodulation and signal processing circuitry is built to convert impedance change into electrical pulses. The pulse signals were acquired by a Lab View program for automatic pulse detection and analysis. The sensing mechanism has been tested on microbeads with high-frequency AC excitation and preliminary results indicate that the pulse amplitude distributions correlate with the size of beads. Further refinement on the sensor design and testing of the device for cell detection and analysis are expected.