All-electronic detection and actuation of single biological cells for lab-on-a-chip applications

A device sensing the change in capacitance as single cells flow through a microfluidic channel past interdigitated electrodes is described. A 0.45 aF resolution within a 3 ms time constant has been achieved. A cellpsilas electrical properties can vary greatly due to ionic currents, double layer effects, and membrane potential gradients (particularly when operating below 200 MHz). Sensing at microwave frequencies (1.6 GHz) greatly reduces these effects. Cells are simultaneously actuated by superimposing a low frequency (LF) signal, producing a dielectrophoretic (DEP) force. As the signal varies with the cellpsilas elevation, the relative magnitude and sign of the DEP force is inferred, without optical sensing.