I. Introduction
Sensing complex multi-modal deformation is critical in the development of soft robots whose large deformations exhibit non-linear mechanical properties [1], [2]. This is because the complex deformations of a soft robot's body and surface caused by contact with the external environment contain a wealth of sensory information. A sensing system is required to design a feedback loop. However, due to the soft robots' deformability, we cannot simply divert traditional sensing systems designed and optimized for stiff and rigid robotic systems. A sensing system for soft-bodied robots ideally should capture multi-modal continuum deformation (e.g., bending, compression, and twisting), be easily installed on the soft body, and measure the deformation distributions.