Dongshin Kim

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Pheromone responses are highly context dependent. For example, the C. elegans pheromone ascaroside C9 (ascr#3) is repulsive to wild-type hermaphrodites, attractive to wild-type males, and usually neutral to "social" hermaphrodites with reduced activity of the npr-1 neuropeptide receptor gene. We show here that these distinct behavioral responses arise from(More)
We show that it is possible to use single layer soft lithography to create deformable polymer membranes within microfluidic chips for performing a variety of microfluidic operations. Single layer microfluidic chips were designed, fabricated, and characterized to demonstrate pumping, sorting, and mixing. Flow rates as high as 0.39 microl min(-1) were(More)
We have developed an in-plane bi-polymer check-valve for controlling microfluidic flow and preventing contamination between solutions by tilizing the elastic force of a swollen hydrogel. The valve was created using microfluidic tectonics, a fabrication procedure that allows construction f microscale components and autonomous systems using liquid-phase(More)
The pressure required to drive flow through a microfluidic device is an important characteristic of that device. We present a method to measure the flow rate through microfluidic components and systems, including micropumps and microvalves. The measurement platform is composed of two pressure sensors and a glass tube, which provides series resistance. The(More)
A fabrication platform for realizing integrated microfluidic devices is discussed. The platform allows for creating specific microsystems for multistep assays in an ad hoc manner as the components that perform the assay steps can be created at any location inside the device via in situ fabrication. The platform was utilized to create a prototype microsystem(More)
While living systems have developed highly efficient ways to convert chemical energy (e.g., ATP hydrolysis) to mechanical motion (e.g., movement of muscle), it remains a challenge to build muscle-like biomimetic systems to generate mechanical force directly from chemical reactions. Here we show that a continuous flow of reactant solution leads to by far the(More)
This paper studies hydrogels created by photopolymerization with a uniform beam of light. Under some conditions the density profiles of the resulting hydrogels were uniform cylinders, mirroring the illumination profiles. However, under other conditions, gels with hollow cylindrical shapes were formed. We studied the photopolymerization of(More)
Communities around the country are facing an increasing number of problems for which traditional government action is failing. This has led to a growing realization that the public sector must increase its capacity to innovate. In an effort to do so, the public sector has increasingly turned to networks of public, private, and non-profit organizations.(More)
The alignment step in fabricating multi-height photoresist masters is a critical and time-consuming process. SU8 masters that combine very thin and thick layers can be difficult to align because of low contrast visibility. We increase visual contrast by selectively developing alignment marks to ease fabrication of masters with thick resist layers deposited(More)