Fabrication of the Lab on a Chip required 3 steps. First, a CAD file was created of the LOC design. Next, acrylic wafers were milled with a CNC machine from the CAD design. Finally, a plain polydimethylsiloxane (PDMS) lid needed to be molded to enclose the channels and wells of the acrylic wafer. The Lab on a Chip needed to be sealed with a flexible lid in order to insert liquid into the wells and channels. In Lab 5, to mold the lids, PDMS resin, a silicone rubber, and a hardener were mixed together and then poured into a petri dish. Mixing the resin and hardener creates bubbles in the solution so a method of degassing was required. A vacuum was used to get rid of any bubbles in the petri dish. A vacuum lowers the pressure causing the bubbles to expand by increasing the volume of gas. The lower pressure also reduces the solubility of air in the liquid causing the bubbles to rise to the surface. Cycling vacuum and atmospheric pressure effectively removed the bubbles to create a defect free mold. The dishes were placed in a desiccator several times in order to remove all of the bubbles. A glass stirring rod was also used to remove any final bubbles that remained. The molds were then cured until the next lab session where they were demolded.
Chip Lid Molding Process
