Abstract

As technology is advancing, more complex, efficient, and powerful devices are being made. These powerful devices generate a lot of heat which needs to be taken out to maximize their performance. Hence, efforts are being made to improve cooling techniques for these devices. Boiling is one such technique used in the cooling of devices. The heat transfer performance in the flow boiling systems is higher than that in pool boiling systems. With a simple add-on tapered manifold over a plain surface, we can convert pool boiling to flow boiling. This study will lead to improved performance and reliability of microelectronic devices, supercomputers, server chips, etc. The forces from bubbles growing can provide a pumpless, self-sustained unidirectional flow effectively transforming pool boiling into the extremely efficient flow boiling, resulting in energy savings. MEMS pressure sensor array will be mounted at the end of tapered manifold to map the pressure field around a nucleating bubble. The thesis describes the design, fabrication, packaging, and testing of a bulk micromachined sensor array that is capable of monitoring the pressure progression of a bubble. The sensor utilizes an extremely thin 225 nm square Si3N4 diaphragm which is produced by etching away the bulk silicon with XeF2 through holes present in the diaphragm. A unique process flow was developed to achieve the diaphragm thickness in nanometers. Four polysilicon piezoresistors, mounted on the surface of the diaphragm, where the stress is maximum, are used by the sensor. The thesis also discusses the results obtained from the response of the fabricated sensor. Various attempts were made to get a voltage output in response to applied pressure. These values were acquired over a number of experiments repeated at similar experimental conditions to demonstrate the repeatability of the calibration data. The value of sensitivity, derived from the slope of the linear calibration plot of Vout (V) vs. Pressure (Pa), is 5.26 μV/Pa, which is very close to the required target hyper-sensitivity of 5 μV/Pa.

Publication Date

8-2022

Document Type

Thesis

Student Type

Graduate

Degree Name

Electrical Engineering (MS)

Department, Program, or Center

Department of Electrical and Microelectronic Engineering (KGCOE)

Advisor

Ivan Puchades

Advisor/Committee Member

Satish G. Kandlikar

Advisor/Committee Member

Robert Pearson

Campus

RIT – Main Campus

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