Fabrication of microfluidic devices through deep wet etching

Abstract

Soda-lime glass is a commonly used, cheap and accessible material. Just like any other glass, it offers unique optical properties. Most of the incoming light is transmitted through the glass, which makes soda-lime an attractive material to be used in analytical and observational purposes. For this reason, glass is an excellent source material for microfluidics practices. Microfluidics is the manipulation of the fluids in micro-scales; enclosed microfluidic systems offers a variety of possibilities in biochemical research, since most bio mechanism operate on micro-scale. However, fabrication of microfluidic systems offer challenges. In this paper, multiple fabrication methods was attempted to create a microfluidic device that can be utilized in cell sorting purposes.

Hydrofluoric acid (HF) is a strong chemical and it is commonly practiced to generate patterns on glass-based materials. To withstand HF, glass surface was covered with either chromium or gold. In this experiment, two different concentrations of HF were tested; 6% and 48% HF. Generation of deep patterns were consuming excessive time with 6% HF, protective mask was unable to withstand the harsh conditions. On the other hand, increasing the concentration by eightfold decreased the time consumption by 47 times. Main findings of this study was the usage of high concentration of HF and application of gold layer, chromium layer was not durable enough. Flow was generated successfully within the device, sample beads were transported effortlessly. Many of the reported methods in this paper can be improved; however, a working fabrication method was developed.