Flexible Fiber Interconnects for Soft Mechatronics

Recent advances in flexible electronics, soft sensors and soft actuators are paving the way towards replacing hard printed circuit boards for soft counterparts in various applications (e.g. soft robotics, wearable devices, etc.). The need to achieve robust electrical connections between both soft and traditional rigid components poses many challenges. In particular, the in-extensiblility of commercially available interconnects (e.g. single/multi-strand conductive wires, conductive metallic tapes, etc.) can affect the structural properties of soft components. Herein we present the design and demonstrate the fabrication method for making flexible fiber interconnects (FFI) by printing flexible guide-paths and simultaneously layering and embedding conductive yarns within. The effectiveness and robustness of the flexible interconnects for use within soft structures is characterized. Simple FFI designs can be used within structures undergoing up to 200% strains without interfering with the substrate stress-strain behavior. Electrical conductivity is also shown to be stable even during cyclic loading.

I. Introduction

Recent advances in materials and fabrication techniques have enabled the development of novel flexible electronics, soft sensors, and soft actuators [1]–[3]. Traditional printed circuit boards, rigid electronic components and batteries are also giving way to soft alternatives for various applications in soft robotics and wearable devices [4], [5]. This shift in hardware configurations has created challenges for electrical connections. Several soft systems are required to undergo large deformations while maintaining stable connectivity between various electrical components. Commonly used interconnections such as insulated conductive wires [6], [7], copper traces [8] and etched copper sheets [9] offer favorable electrical properties, but they are not flexible enough and can affect the structural properties of soft mechatronic components.