Still image from a video shows how one circuit serves as the clocking signal of another circuit so that the branching fluids switch in unison. (Image courtesy of University of Michigan)

In order to simplify lab-on-a-chip devices for portable medical tests, University of Michigan researchers have created microfluidic integrated circuits. As reported in Science Daily, these microfluidic circuits regulate fluid flow without assistance from outside systems—just as electronic circuits route the flow of electricity on computer chips without external controls.

"In most microfluidic devices today, there are essentially little fingers or pressure forces that open and close each individual valve to route fluid through the device during experiments,” explains Shu Takayama, an associate professor in the University of Michigan department of biomedical engineering and the principal investigator on the project. “That is, there is an extra layer of control machinery that is required to manipulate the current in the fluidic circuit." Bobak Mosadegh, a doctoral student in Takayama's lab, adds, "We have literally made a microfluidic integrated circuit." A paper on this work, "Integrated Elastomeric Components for Autonomous Regulation of Sequential and Oscillatory Flow Switching in Microfluidic Devices," appears in the journal Nature Physics.

Microfluidic technology has been hindered by the requirement that each valve on a chip must be controlled by an off-chip actuator or pump. To overcome this limitation, Takayama’s research group has devised a strategy for automatically networking the fluidic counterparts of key electrical components—including transistors, diodes, resistors, and capacitors—to regulate fluid flow. Since these components are made using conventional techniques, they are compatible with all other microfluidic components, such as mixers, filters, and cell culture chambers, the researchers remark.

"We've made a versatile control system," Mosadegh said. "We envision that this technology will become a platform for researchers and companies in the microfluidics field to develop sophisticated self-controlled microfluidic devices that automatically process biofluids such as blood and pharmaceuticals for diagnostics or other applications. Just as the integrated circuit brought the digital information processing power of computers to the people, we envision our microfluidic analog will be able to do the same for cellular and biochemical information."