Fabrication of Circular Microfluidic Channels in Hydrogel

Jonah Schwartz

Mentor: Gayatri Pahapale.

Supervisor: Dr. David Gracias.

All tissues in our body are interspersed with a vast network of microchannels that facilitate nutrient and oxygen distribution to cells and also drain the waste out from the cell. To mimic this network of microchannels in a laboratory setting, researchers use microfluidic channels, which are essentially microchannels or ducts through the cells' environment. The most common technique used to fabricate the microfluidic devices is lithography, which yields channels with square and rectangular cross sections. However, channels in the body are circular, so that feature is very valuable. Although there are methods like micro-milling and 3D printing to create circular channels, these do not offer the flexibility of material, design, and scalability. Thus, it is still challenging to create channels that simulate the geometry of the in vivo channels and are also biocompatible. This paper will discuss the fabrication of circular microfluidic channels using reflow lithography and soft molding. In a lab setting, we would mold the half channels created by lithography onto a gelatin hydrogel and bond the two halves using adhesive such as transglutaminase to create a fully cylindrical channel. Gelatin is biocompatible and acts as an extracellular matrix that would simulate in vivo. This method is efficient and straightforward, allowing rapid fabrication of a variety of microchannels. Unfortunately, due to lack of lab equipment, the experiment shown in this paper is a simplified representation of that; using sacrificial layers of various sizes in jello to form our channels, as well as experimenting with tree shaped channels that have many branches that form a network. Creating microchannels quickly and efficiently is essential for tissue engineering, and this study will offer a facile method for microfluidic fabrication.