Improvements in Microboiling Device Design

Abstract

Small ribbon heaters (10 μm - 20 μm wide) have been used for many years to study the formation of microbubbles in liquids when short voltage pulses are applied. This thesis describes improvements in the device design with an emphasis on smaller and more sensitive heaters. I used a novel method of creating 250 nanometer wide heaters to keep both the fabrication time and costs as low as possible by using a focused ion beam to create the heaters from a set of larger devices. Ribbon heaters are usually fabricated on a thin SiO2 layer on a silicon wafer which acts as a large heat sink whose effect becomes more pronounced the smaller the heater width. Suspending the heaters on a thin membrane dramatically increased their sensitivity in microboiling experiments. The suspended devices required the development of a very low stress platinum deposition process.