Bubble nucleation on micro line heaters under steady or finite pulse of voltage input

Nucleation temperatures on micro line heaters under steady voltage input were measured precisely by obtaining the I-R (current-resistance) characteristic curves of the heaters having dimensions of 50 μm in length, 3 or 5 μm in width, and 0.583 μm in thickness. The bubble nucleation temperature on the heater with 3 μm width is higher than the superheat limit, while the temperature on the heater with broader width of 5 μm is considerably less than the superheat limit. The nucleation temperature under a finite voltage pulse input was also measured for 5-μm width heater. The nucleation temperatures were also estimated by using the molecular cluster model for bubble nucleation on the cavity free surface with effect of contact angle. The bubble nucleation process was observed by a microscope/35 mm camera unit with a flash light of μs duration.