Research

Fluidic control

Microfluidic devices are promising for high throughput and complex analysis/production of biochemicals. For the task, the devices are becoming increasingly sophisticated, integrating increasingly larger numbers of expensive external controllers such as power supplies and syringe pumps. With this control-challenge that hampers broader use of microfluidic devices for high throughput and high complexity analysis/production, new ways to enable sophisticated on-chip control with a minimal reliance on external controllers are necessary.

Motivation and approach I

With only a power source, an electronic circuit implements sophisticated autonomous functions (i.e. no aid by other external units). Such functions are enabled by the smart arrangement of electronic transistors, resistors, and capacitors. Notably, an interesting analogy exists between electric and microfluidic parameters: electric resistors correspond to microfluidic channels having fluids, capacitors to chambers having elastomeric membranes, and electronic transistors to elastomeric valves. With this analogy, we mimic useful electric/electronic functions and develop new microfluidic devices. The devices are utilized to study cellular rhythms and to synthesize new materials.

Motivation and approach II

Surface tension is an intriguing phenomenon: The meniscus shape of a liquid-gas interface causes a pressure gradient in a liquid and drives the liquid’s spontaneous motion. Thus, when we use surface tension, we only need a very small and simple external control unit or none at all. However, sophisticated regulation of the streams by only surface tension is nontrivial. Here, we study the surface tension in an engineering viewpoint, look for its sophisticated control mechanism, and develop new microfluidic devices. The devices are used for bioassays such as immunoassay and nucleic acid testing.