Multi-Modal Microfluidic Bend Sensor for Soft and Robotic Sensing Applications*

Bend sensors play a pivotal role in gaining insights into the dynamic behavior of flexible mechanical systems and bolstering safety considerations. This paper introduces a novel microfluidic-based multi-modal bend sensor that offers tremendous potential for a wide range of applications, especially in robotics and microsystems. Our bend sensor features a flexible substrate embedded with a liquid metal-filled microchannel filled. The fabrication process utilizes simple and cost-effective 3D printing and soft-lithography techniques. As the microchannel deforms, the sensor measures changes in electrical resistance across its terminals, providing reliable indications of bending intensity and direction. By incorporating rectangular through-voids in close proximity underneath the serpentine microchannel, the bending-induced change in the length and cross-sectional area of the microchannel is magnified. This resulted in an enhanced bending sensitivity. Experimental characterizations demonstrate the sensor's effectiveness and versatility under various bending conditions. Furthermore, the sensor is capable of detecting the amount of applied pressure as well as the degree of twisting, expanding its functionality. With its soft and flexible nature, the novel multi-modal bend sensor can be seamlessly integrated into wearable technology and soft robotics applications, offering real-time insights into bending, pressure, and twisting for improved safety and control.