Electrohydrodynamic Direct-Writing Fabrication of Microstructure-Enhanced Microelectrode Arrays for Customized and Curved Physiological Electronics

Metal-based patterned conductors have a key role in flexible and curved micro/nanodevices. However, the fabrication of micro/nanoscale metal-based electrodes with excellent electrical conductivities and well-organized flexible/curved polymeric substrates remains a major challenge associated with a posttreatment. In this study, a maskless and direct-writing method of electrohydrodynamic jet (e-jet) printing combined with the conventional wet etching process is developed for fabrication of microscale conductive features of microstructure-enhanced patterned electrodes without high-temperature treatment. Customized metal-patterned electrodes and various metal-patterned electrode arrays are fabricated on a flexible/curved polyethylene terephthalate substrate. In addition, ultraviolet-curable hierarchical micro/nanostructures can be fabricated by stable cone-jet and electrospray modes. The results of electrocardiography (ECG) and electromyography signal measurements show that the added microstructures can increase the contact between the metal microelectrodes and skin surface, which yield lower disturbance and baseline drift and enable a stable ECG signal acquisition. Overall, e-jet printing is a promising mask-free approach for fabrication of conductive metal patterns for flexible and stretchable devices.