Test Structures for Stepwise Deformation Sensing on Super-flexible Strain Sensors

Developing MEMS sensors with a high strain sensing range (up to 0.6) and a stepwise sensing mechanism could enable widespread downstream applications, by allowing intimate, mechanically conformable integration with soft biological tissues. Most approaches to date focus on challenges to associate the sensing mechanism with high peak strains under large deformation. By designing and characterizing test structures with multi-switching electrodes on super-flexible substrates, this research has established a strategy for stepwise strain-sensing mechanism based on elastic instabilities. The growing and co-existence of wrinkles and creases on multiple electrodes with different dimensions are observed under lateral strains ranging between 0.3 and 0.6. Initial electrical measurements of the multi-switching mechanism has been demonstrated with a two stage resistance value change observed under changing compressive strain. Further investigation will focus on the device optimization and mechano-electrical signal processing.