Direct ink writing of flexible electronic circuits and their characterization

Abstract

The present work discusses the fabrication of low-cost, reliable and durable flexible electronic circuits from conductive carbon paste on flexible polyethylene terephthalate (PET) substrate using microdispensing direct ink write technique. Printing parameters such as pressure, substrate speed and gap size are optimized through Box–Behnken experimental design technique to achieve the desired quality of prints (patterns). For the nozzle with an inner diameter of 200\xa0µm, the system is able to produce pattern line width ranging from 198\xa0µm to 295\xa0µm, respectively. Based on optimized parameters, circuits such as foil grid and rectangular spiral are printed on a flexible PET substrate. The deposited patterns of circuits are morphologically characterized by optical microscopy and scanning electronic microscopy. Current–Voltage (I–V) characteristic is performed to evaluate the conductive performance of circuits. The sensitivity of circuits to bending is assessed by studying resistance response under fully bend and unbend angle of 90° and 0°. Durability and reliability of circuits are analyzed by subjecting circuits to continuous 500 bend cycles and study its resistance response. The analysis revealed that these direct ink write circuits are reliable, durable and stable in performance and are applicable to the flexible electronic application.