Design, mechanics, and operation of spiral-interconnect based networked sensor for stretchable electronics

Currently, stretchable electronics has gained intensive attention due to its numerous applications, especially for implantable medical diagnostics and soft actuator based surgeries. A practical stretchable system requires the use of a feedback-assisted structure, i.e., that can detect the movement of the device, analyze the data, and manage the motion, referred to as digitally controlled actuation. An island-interconnect configuration is used to attain the stretchable electronics such as a spiral interconnect is commonly used architecture due to its high stretchability and ability to accommodate large deformations. Here, we fabricate the microscale stretchable series networks and experimentally demonstrate their stretching profiles. A systematic comparison using experiments and finite element method modeling illustrates the mechanical response of the series network up to their fracture limit and shows the stretchability of 160% before the fracture. Cyclic testing shows that the spiral-interconnect experiences no fracture up to 412 cycles. We then devise a sensing mechanism, which detects the actual movement of the island during stretching. The sensitivity and resolution of the sensing mechanism are 1.4 fF/μm and 0.7 μm, respectively. Our proposed sensing mechanism might digitally control the soft robotic-arms and actuators for next-generation drug delivery and targeted application of artificial entities.