Fabrication of Microfluidcs Channel with Bilayer Mo Mask and glass bonding using custom design clamp

Abstract

Fabrication of microfluidic channel with the right compatibility between microfluidic substrate and fluid is one of major challenge. In addition, fabrication of a deep microfluidic channel with smooth walls is another challenge. To overcome these challenges, this paper presents the fabrication and bonding of microfluidic deep channel on a glass substrate. For the fabrication of deep microfluidic channels a novel good quality bi-layer molybdenum (Mo) film deposited by sputtering is used as a mask for the wet etching of bulk glass substrate. The Mo mask is able to sustain the BOE mixed with HCl solution attack during wet etching process to assist in the formation of deep channels. It is found that maximum channel depth of $390 \mu\mathrm{m}$ is obtained with optimized parameters. It is also observed that compared to BOE mixed with HCl, BOE: HNO 3 has higher etch rate and provides smooth channels using the Mo mask. This leads to formation of comparatively deeper channels. Further, glass to glass bonding is achieved by a unique and custom made clamp designed without using any weights. The fabricated microfluidic deep channels in glass substrates can find potential application in the microfluidic heat sink electronic circuits and bio fluidic sensor applications. Also, the structures like cantilever and valves can be easily integrated inside the deep microfluidic channel for further advanced MEMs device applications.