We are 3D printing SARS-COVID-19 vaccine microneedle patches. This image shows a CFD simulation of a microneedle forming in a PDMS mold. Air is being pulled into the semi-permeable PDMS mold by a negative pressure suction while polymer flows into a cavity to form a semi-conical microneedle. Each air and fluid particle is identified and represented in different color path lines. I took this image to investigate microneedle formation behavior and predict polymer loading time.