On-chip integation of microfluid and cell detector for micro cell counter

Abstract

This paper describes on-chip integration of microfluid and cell detector for a micro cell counter. The device consists of a microchannel, a microwindow, a boron diffused resistor (BDR). It utilizes photoconductive property of the BDR, for detection, which shows the resistance change up to 10% when illuminated. The microchannel is made by transparent PDMS and the microwindow is made by opening metal film on glass substrate. When the cells pass the microwindow during transport in the microchannel by a peristaltic pump they shade illumination, from a fiber optic illuminator, on the BDR. Counting is performed due to resistance change (DeltaR) of the BDR at the moment. In the method the cells can be preserved intact because they are free from the electric field or the attachment of fluorescent markers which is conventional in the impedance spectroscopy method or the fluorescent activation method, respectively. The experiments with Sephadex G-25 beads ranging 70 to 100 mum in diameter showed signals of 20 mV. The detection principle and design are described in text, and the fabrication and experiments as well.