Strain-Induced Performance Variation in Stretchable Carbon-Nanotube Thin-Film Transistors and the Solution Through a Circular Channel Design

Taking flexible technology to a new level, intrinsically stretchable electronics enable new sensing capabilities by facilitating seamless integration of cyber-physical electronic systems with the human body. This is made possible by their superior mechanical characteristics that are capable of accommodating the dynamical movement and shape changes of soft biological tissues without asserting excessive constraints. While previous stretchable thin-film transistors (TFTs) could only operate at subkilohertz, our recent advancements in materials and fabrication processes have pushed stretchable TFT speed to the megahertz regime, rivaling that of the state-of-the-art flexible technologies. However, under deformation, significant change in device characteristics remains a major challenge that hinders circuit and system design for practical applications. In this study, we conduct a systematic analysis to identify the causes for the performance variations and present a novel circular channel design to mitigate strain impact on electrical performance. We show that this design significantly reduces the strain-induced current variation, from over 50 % to only a few percentages. This is due to the cancellation of the variations across different orientations within a 360(degrees) TFT channel.