A micromachined high throughput Coulter counter for bioparticle detection and counting

We describe a micromachined Coulter counter with multiple sensing microchannels for quantitative measurement of polymethacrylate particles and pollen. A unique design with sensing microelectrodes in the center of the microchannels is demonstrated. This design creates isolation resistances among channels, and thus circumvents the crosstalk caused by automatic electrical connection among microchannels. When implemented using microfluidic channels, this design is appropriate for the sensing of microscale particles in deionized water or in dilute electrolyte solution. Our design has multiple channels operating in parallel, but integrated with just one sample reservoir and one power source. The results with a four-channel device show that this device is capable of differentiating and counting micro polymethacrylate particles and Juniper pollen rapidly. Moreover, the device throughput is improved significantly in comparison to a single-channel device. The concept can be extended to a large number of sensing channels in a single chip for significant improvement in throughput.