Triple-State Liquid-Based Microfluidic Tactile Sensor with High Flexibility, Durability, and Sensitivity

We develop a novel triple-state liquid-based resistive microfluidic tactile sensor with high flexibility, durability, and sensitivity. It comprises a platinum-cured silicone microfluidic assembly filled with 2 μL liquid metallic alloy interfacing two screen-printed conductive electrodes on a polyethylene terephthalate (PET) film. This flexible tactile sensor is highly sensitive ((2-20) × 10^-3 kPa^-1) and capable of distinguishing compressive loads with an extremely large range of pressure (2 to 400 kPa) as well as bending loads. Owing to its unique and durable structure, the sensor can withstand numerous severe mechanical load, such as foot stomping and a car wheel rolling over it, without compromising its electrical signal stability and overall integrity. Also, our sensing device is highly deformable, wearable, and able to differentiate and quantify pressures exerted by distinct bodily actions, such as a finger touch or footstep pressure. As a proof-of-concept of the applicability of our tactile sensor, we demonstrate the measurements of localized dynamic foot pressure by embedding the sensor inside the shoes and high heels. This work highlights the potential of the liquid-based microfluidic tactile sensing platform in a wide range of applications and can facilitate the realization of functional liquid-state sensing device technology with superior mechanical flexibility, durability, and sensitivity.