Design and demonstration of a novel micro-Coulter counter utilizing liquid metal electrodes

This paper describes the design and demonstration of a novel, easily fabricated micro-Coulter counter utilizing liquid metal electrodes. Fluid and electrode channels were fabricated simultaneously in a single lithographic patterning step. Eutectic gallium-indium (EGaIn) was injected into the device to form functional electrodes in a cross-channel parallel configuration. Functionality of the device was demonstrated at an ac excitation frequency of 5 kHz using a polymer microsphere suspension and simple post-processing techniques. The device successfully detected particles, exhibiting an output response proportional to particle size. EGaIn was demonstrated to be an effective micro-fluidic electrode material and provided a novel approach for the fabrication of a functional micro-Coulter counter.