A fluid model of pulsed direct current planar magnetron discharge.

We simulated a pulsed direct current (DC) planar magnetron discharge using fluid model, solving for species continuity, momentum, and energy transfer equations, coupled with Poisson equation and Lorentz force for electromagnetism. Based on a validated DC magnetron model, an asymmetric bipolar potential waveform is applied at the cathode at 50-200 kHz frequency and 50-80% duty cycle. Our results show that pulsing leads to increased electron density and electron temperature, but decreased deposition rate over non-pulsed DC magnetron, trends consistent with those reported by experimental studies.

Nanodroplet Depinning from Nanoparticles.

Nanoscale defects on a substrate affect the sliding motion of water droplets. Using in situ transmission electron microscopy imaging, we visualized the depinning dynamics of water nanodroplets from gold nanoparticles on a flat SiNx surface. Our observations showed that nanoscale pinning effects of the gold nanoparticle oppose the lateral forces, resulting in stretching, even breakup, of the water nanodroplet.

Fabrication of nanoscale nozzle for electrohydrodynamic (EHD) inkjet head and high precision patterning by drop-on-demand operation.

Electrohydrodynamic (EHD) spraying has been utilized in applications varying from micro-colloid thrusters to technology for film deposition and inkjet printing. Recently, EHD inkjet heads were developed to facilitate the fabrication of printed electronics such as digital displays, printed circuit boards (PCBs), and solar cells. Here, we report the fabrication and application of nanoscale nozzles for EHD inkjet printing.

Liquid meniscus oscillation and drop ejection by ac voltage, pulsed dc voltage, and superimposing dc to ac voltages.

The electrohydrodynamic (EHD) spraying technique has been utilized in applications such as inkjet printing and mass spectrometry technologies. In this paper, the role of electrical potential signals in jetting and on the oscillation of the meniscus is evaluated. The jetting and the meniscus oscillation behavior are experimentally investigated under ac voltage, ac voltage superimposed on dc voltage, and pulsed dc voltage.