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Bubble Nucleation of Highly Superheated Water on Thin Film Platinum Films supported by SiN Membranes using a Low-Noise Bridge Circuit

Published

Author(s)

Eric J. Ching, Michael J. Carrier, C. T. Avedisian, James R. Young, Bruce R. Land, Richard E. Cavicchi

Abstract

This study describes the use of stress-minimized thin film platinum (Pt) membrane configurations (200 nm thick, 150 μm long, 10 μm wide) for promoting bubble nucleation of water near its superheat limit. The membrane designs consist of Pt films deposited on 200 nm thick SiN layers over bulk Si, with membranes being formed after etching Si from the back side. Results are compared with more conventional Pt films supported by SiO2 and Si substrates. The average metal temperature is monitored by a bridge circuit with capacitive and inductive filtering to reduce noise in the output signal. Voltage pulses ranging between 0.5 μs to 20 μs are imposed on the bridge to electrically heat the Pt film, and bubble nucleation occurs at temperatures that are obtained by converting the measured resistance to temperature after a calibration. The paper includes discussion of fabrication of the films, the bridge circuit design for monitoring the change in electrical resistance during the power pulse, the temperature calibration process, and the experimental procedure for measuring the temperature during a power pulse. The results show that approximately 26% less energy is needed to trigger bubble nucleation at the superheat limit of water for a microheater fabricated on a membrane compared to a microheater of the same aspect ratio fabricated onto a bulk Si substrate. The highest nucleation temperatures were realized at heating rates of nearly 109 °C/s. The potential for employing back-side etched devices is suggested for both fundamental studies of phase transitions of highly superheated liquids and in applications where bubble nucleation is an important process such as for ink-jet printers and microscale bubble pump designs.
Citation
International Journal of Heat and Mass Transfer
Volume
79

Keywords

boiling, superheat, bubble nucleation, inkjet, bubbles, printer, microscale, bubble pump, homogeneous nucleation

Citation

Ching, E. , Carrier, M. , Avedisian, C. , Young, J. , Land, B. and Cavicchi, R. (2014), Bubble Nucleation of Highly Superheated Water on Thin Film Platinum Films supported by SiN Membranes using a Low-Noise Bridge Circuit, International Journal of Heat and Mass Transfer, [online], https://doi.org/10.1016/j.ijheatmasstransfer.2014.07.081 (Accessed April 19, 2024)
Created November 30, 2014, Updated October 12, 2021