Drop-on-Demand Electrohydrodynamic Printing of High Resolution Conductive Micro Patterns for MEMS Repairing

Electrohydrodynamic (EHD) printing was employed here to fabricate conductive micro patterns for printed electronic devices. EHD printing offers fine pattern fabrication through additive manufacturing that has several advantages when compared to conventional lithographic techniques. One of the major advantages of additive manufacturing is its ability to print on already fabricated devices for the purpose of alteration or repair. However, printing of micro patterns on a fabricated MEMS device is a tedious task due to the electrostatically induced disturbances in cone jet and the formation of satellite droplets. In this study, a modified EHD printing technique called drop on demand (DOD) process was used to print silver micro patterns on a MEMS device with high accuracy. The focus here was to optimize the technique and parameters, and modify the system hardware to enable patterning on an un-treated device surface. Parameters like supply voltage, waveform shape and frequency, pneumatic pressure, and ink flow rate have been studied and optimized to achieve repeatable and stable conductive patterns up to 3 mu m. The modified EHD-DOD system also eliminates the problem of static surface charges by using low voltage thus enabling printing of highly repeatable sub-10 mu m conductive patterns well suitable for MEMS repair.