Facile Fabrication of Microfluidic Chips for Education
Authors:Hina Bhatia, Rahul Venkatraman
Mentor:Roger. C. Lo, Professor of Chemical Engineering , California State University, Long Beach
Microfluidics is an emerging field that represents the cusp of semiconductor fabrication and chemical engineering systems. Microfluidic devices operate primarily in the laminar flow regime, where mixing takes place due to diffusion or changing geometry such as bends or turns. Incredibly sophisticated and portable reactor systems can be fabricated to manipulate miniature amounts of fluids. Its applications vary from wastewater testing to on-site drug production. As microfluidics finds increasing applications in new areas, there is a strong need for general awareness and in-depth understanding in chemical engineering education. However, when it comes to giving students a hands-on experience in this exciting area, an educator is often faced with prohibiting constraints, such as the cost of materials and the need for hands-on cleanroom training to fabricate these microfluidic devices. In this work, we present a quick and inexpensive way to fabricate simple microfluidic chips for educational purposes. Tubular geometries were patterned on paper wafers using a hot glue gun, and then microchips were cast in Knox Gelatin. Whole milk with red and blue food coloring was used as the operating fluid because it was dense and provided high contrast. Simple Y-shaped channels were used to demonstrate two- and three- channel contacting patterns that have boundary layers and slow diffusion mixing zones. Effective laminar mixing by using bends was observed on a two-channel serpentine. We fabricated a pH test chip using pH paper embedded in a straight channel chip. Acids and bases were pumped into the microchannel to demonstrate pH tests. We also taught students to etch copper-coated slides to perform pattern transfer to make their souvenirs at the end of the 16-hour lab session. The total budget was less than $500 for 30 students.