Small volume fluid handling in single and multiphase microfluidics provides a promising strategy for efficient biochemical assays, low-cost point-of-care diagnostics and science kits for educational applications. A significant barrier towards low-cost field deployment of programmable microfluidics is that incorporating multiple pumps, mixers and discrete valve based control of nanoliter droplets in an integrated, programmable manner without external bulky components has remained elusive. Here, a self-contained, hand-crank driven, multiplex and robust programmable microfluidic platform, combining the idea of punch card programming with arbitrary microfluidic control is presented. A paper tape encodes information as a series of punched holes. A mechanical reader/actuator reads these tapes and correspondingly executes a series of operations onto a microfluidic chip coupled to the platform in a plug-and-play fashion. Enabled by the complexity of codes that can be represented by a series of holes in punched paper tapes, we demonstrate independent control of 15 on-chip pumps with enhanced mixing, on-off valves and novel on-demand impact based droplet generators. A water quality assay utilizing colorimetric assay for pH, ammonia, nitrites and nitrates is presented as an example. With its portable and robust design, low-cost and ease-of-use, we envision punch card programmable microfluidics will bring complex control of microfluidic chips into field-based applications in low-resource settings and children around the world thus bringing microfluidics and low-Reynolds number hydrodynamics to everyday classrooms.
Born and raised in Nakuru, Kenya, George is a graduate student at Stanford University with a passion for developing medical technologies especially for low resource settings. Inspired by his mother who was a nurse, he often found great joy in performing first-aid on his siblings whenever they would get hurt while playing out in the field when he was younger. Discovering his love and aptitude for the sciences and hoping to find ways to help improve health outcomes for his countrymen, George left Kenya to study engineering at Harvey Mudd College. Prior to coming to Stanford, he got additional training at Johns Hopkins as a masters student in biomedical engineering, the World Health Organization as part of its technology and facilities team, as a research engineer in two medical device firms, and as a lab technologist at the Massachusetts General Hospital cancer center and the center for engineering in medicine. Currently in his third year in a joint program of a masters in medicine and bioengineering phd, George is developing a technology platform that he invented with his advisor that can potentially be used for medical diagnostics, monitoring the environment and science education, for extremely resource limited settings. He sees his work as a way to contribute towards breaking down barriers and helping get access to potentially life-saving technologies to people who have been traditionally underserved all over the world. Outside of the lab, he enjoys tending to crops, trail running and exploring the great outdoors.