An array of 44 resistance temperature sensors with a radial resolution of 35 μm was fabricated around a re-entrant cavity (3 μm mouth diameter) on a thin silicon diaphragm with the intended purpose of obtaining highly resolved spatial and temporal measurements of the wall surface temperature during the boiling process. An Argon ion laser beam was used to provide a constant net flux of thermal energy to the backside of the diaphragm underneath the cavity and sensor area. This microsystem initiates and grows a single bubble at the center of the radial sensor array; all while the temperature variation underneath the bubble region during growth, departure, and rewetting is being measured with a frequency of 10 kHz. A high-speed CCD camera capable of taking over 3700 pictures per second is used to monitor the growth rate and departure process of the bubble from the surface, and correlated with the surface temperature measurement. The resulting temperature data can then be used to calculate the variation of the heat transfer coefficient under the bubble during the process of growth, departure, and rewetting. This experimental study provided unique experimental data to evaluate varieties of theories and speculations about the dynamics of bubbling at a microscale level. The focus of the current paper is on the details of the apparatus development and fabrication.
High-speed photodamage cell selection using a frequency-doubled argon ion laser
