ENHANCED ELECTRO-OSMOTIC FLOW PUMP FOR MICRO-SCALE HEAT EXCHANGERS

Non-uniform heat flux generated by microchips can create "hot spots" in localized areas on the microchip surface. This research presents an improved design of an active cooling electro-osmotic flow (EOF) based micro-pump for hot spots thermal management. The design of the micro-pump was simpler and more practical for the application compared to designs presented in literature. Most micro-channel heat sink devices presented in literature were silicon based. Though silicon has better thermal conductivity when compared to polymers used in micro-devices fabrication, processes of silicon fabrication are complicated and time consuming. Also, most micro-channel fabrication processes use silicon etching which leads to rough walls within the micro-channel. An improved design, which uses a combination of silicon and Polydimethylsiloxane (PDMS), is being developed and tested. The main idea of this design is to utilize the favorable thermal properties of silicon while achieving both smoother charged surfaces and ease of fabrication of PDMS material. The EOF micro-pump was tested for four cooling fluid namely, DI water, distilled water, borax buffer, and Al2O3 nanoparticles suspended in water solution. A maximum flow rate of 31.2 mu L/min was achieved using distilled water at 500 V of EOF voltage. Such micro-pump with this flow rate range can be implemented in a closed loop heat rejection system for hot spot thermal management. Moreover, it can be used in Lap-on-chip and uTAS application for sample transport.