A Low-cost Microfluidic Device to Study Nonequilibrium Physics of Colloids

Microfluidics is a field of research that involves manipulating micron-scale volumes of fluids. Microfluidic devices have many applications; in our lab, we use microfluidic devices to study active colloidal particles. In this study we develop a low-cost microfluidic device and use the device to study the dynamics of microscopic particles. To create a low-cost microfluidic device in the lab, we implement a method pioneered by Michelle Khine at UCI which utilizes inexpensive equipment. Materials needed to build a functioning chip are: an oven, a handheld Corona discharger, Shrinky-Dinks, and polydimethylsiloxane (PDMS). In a matter of minutes, a complete microfluidic device can be made. We use the devices to study the nonequilibrium dynamics of active self-propelled colloids. Active colloids are spherical particles that have a hematite cube embedded in them to create a Janus particle. These active colloids, under equilibrium conditions, undergo Brownian motion; however, when the particles are illuminated with blue light, they self-propel and generate active motion. We use microfluidic devices to study the dynamics of active colloids under flow. Our low-cost microfluidic devices allow us to study the microscale motion and force dynamics of active colloids.