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Liwei Lin, P.I.

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Program Goals:

The proposed research responds to the need for a low-power, constant-operation, self-contained and long shelf-life biological sample acquisition and assay system. The Berkeley Sensor & Actuator Center (BSAC) of the University of California at Berkeley with direct support of a BSAC Industrial Member Company is developing the technology for a fully integrated, fully regulated system for the acquisition, metering, buffering, delivery and assay of fluid biological samples based upon an innovative, water-powered microfluidic system.

Technical Approach:
In order to implement a wristwatch-sized bioassay system for long live, the issues of power, sample acquisition and assay must be directly addressed. In this research, these issues are mitigated by combining a micro dialysis needle, an osmotic pump system and an enzymatic assay. The micro dialysis needle will allow the acquisition of lactate from interstitial fluid in the human

body. The implementation of dialysis right at the point of sample acquisition in the interstitial layer of skin unburdens the system from many subsequent sample preparation issues such as the separation of red blood cells from the sample. The osmotic pump provides pumping power from the introduction of water. No electrical power need be consumed for the transport of fluid, and so the elimination of electrical pumping power makes possible extremely long system life. Further, the development of microvalves that require only 4 micro-Watts for actuation means that a standard wristwatch batter has the potential of powering the water-powered bioassay system for 1 to 3 years. Finally, the use of an enzymatic reaction to convert the lactate to hydrogen peroxide makes possible continuous testing. No enzyme is consumed in the assay process and the assay fluid may be intermittently pumped through the system on an ongoing basis, with an assay done each time a new slug of fluid is passed through the system.