Design, fabrication and characterization of an integrated micro heat pipe

The design, fabrication and characterization of an integrated microsystem consisting of micro heat pipes, a micro heater, temperature and capacitive microsensors are presented. CMOS-compatible micromachining techniques are utilized to fabricate the micro heat pipe device capped by a nitride layer. In order to allow clear visualization of flow patterns during operation, the process has been modified using a glass wafer to cap the heat pipes. Temperature distributions along the micro heat pipes have been measured using the microsensors located next to the heat pipes. The capacitive microsensors have been used to measure the void-fraction, taking advantage of the large difference between the dielectric constants of the liquid and vapor phases.