Low cost procedure for fabrication of micro-nozzles and micro-diffusers

Abstract

In this paper, we present a simple, rapid, and low-cost procedure for fabricating micro-nozzles and micro-diffusers using in microfluidic devices to control the flow of the fluid which pass through the microchannels. This procedure uses commercially accessible and typical materials, which is used in several applications in microelectronic labs. Glass is used as main substrate to get advantages of photo transparent specifications of this material. In this method a thick layer of positive photoresist on the glass substrate for fabrication of lens is utilized. A mild BOE solution with additional HCL is employed to achieve an excellent etching quality and a smoother etched surface. The depth of the surface can be reach to 100µm without PR damage effect after 1 hour of etching process. The aluminum evaporation process produces a thin layer of aluminum across the substrate which makes it as a block against passing the light. Dispensing SU-8 on Al layer and using UV back-exposure technique the tapered structured is fabricated as a mold for PDMS which can be used in different microfluidic applications. The simulation results shows that the focal length up to 800µm with the lens curvature of 150µm is achievable.