Bubble Nucleation Pulse-Width in Thermal Inkjet Actuators Open Access

Thermal inkjet actuators operate by passing a current through an electrical resistor, the heater, in contact with a working liquid such as ink. This heats the liquid rapidly (dT/dt ≈ 10⁸–10⁹ K/s), and once the liquid temperature exceeds the superheat limit, it flash boils. The resultant high temperature (≈300° and pressure (≈ 10 MPa) bubble expands, forcing the ink through a nozzle, forming a droplet which then travels through the print gap until it strikes the media. Here, we discuss the bubble nucleation criterion for thermal inkjet technology, using numerical and analytical models. The models give comparable results, with differences of ten percent or less. These values are also found to compare fairly well with data from bubble visualization and droplet weight experiments.