In preliminary work to confirm that the zoospores could indeed be detected passing the electrodes, and to confirm that the frequency dependence of the signal was roughly as expected from the simulations presented in Figure , the zoospores were introduced into the microfluidic channel (constriction 5 in Figure ) by a flow generated by the syringe pump, while the in-phase current response to a fixed frequency (5k -300k Hz). AC signal was monitored in real-time. The passing of zoospores successfully triggered a sharp peak in the recorded signal (Figure ), which visual observation confirmed was indeed due to the passage of a spore between the electrodes (Support Information Video 3). The amplitude and the signal-to-noise ratio (SNR) demonstrated a clear dependence on the AC frequency of the input potential sine wave. The statistical analysis of the sensing signal is presented in Figure . The behaviour was as expected from the design considerations presented above. An optimum SNR was found at around 50 kHz.