A hybrid bacteria and microparticle detection platform on a CMOS chip: Design, simulation and testing considerations

This paper presents a hybrid bacteria and microparticles detection platform based on a CMOS technology. Vertical face to face microelectrode arrays are implemented onto CMOS chips by connecting the metal and via layers together. A CMOS post-processing procedure based on Deep Reactive Ion Etching (DRIE) is used to release the microelectrodes and to construct microchannels in between. With medium flow of the fluid, Bacteria and microparticles are allowed to pass through the microchannels, where impedance variations are measured using a microelectrode pair on the wall, and then detected by electronic circuits embedded on the same chip. This microelectronic/microfluidic hybrid system targets screening individual bacterium or microparticle with high throughput and accuracy. The system architecture is presented first, followed by the detailed model, design, simulation and parameters of the prototype. The CMOS post-processing, specific packaging and testing procedures are also introduced in this paper. Finite element analysis method (FEM) and circuit simulations confirm that a single microparticle, 5 μm in diameter, can be detected by the proposed microsystem. Based on preliminary etching results, pairs of released electrodes 10 μm *2 μm *8 μm (L x W x H), also contribute to validate the feasibility of the CMOS post-processing procedure.