Automated Cycling System for Characterizing Ink-Jet Printed Flexible Films for Sensors

Reliability testing of electronic devices is vital; anything from temperature and humidity resistance to mechanical fatigue of materials needs to be tested to ensure devices can hold up to their needed life expectancy— particularly in the field of biosensors and flexible conductors. Unfortunately, the research for specific techniques can be scarce, and often devices need to be tested in their own unique way. In this work, we have developed an automated system for reliability testing of strain-dependent sensors through the cyclic bending of a polyimide substrate with a conductive graphene film. A device was created using a 180-degree servo motor in combination with an Arduino microcontroller. The servo motor was then paired with a rack and pinion gear set to function as a linear actuator and bound to an independently built sliding mechanism that serves as the control and measurement of repeated bending operations. The substrate with the graphene film was then attached to a source meter to measure the current flow in situ over time. Subsequently, this device was able to repeat multiple bend cycles identically, eliminating the need to do it by hand and creating uniformity toward data gathering for comparative experimental studies. As such, the automated cycling system fulfilled its purpose towards a reliability test for which the graphene film showed the ability to withstand fatigue through repeated loading.