Fabrication and characterization of human finger ridge-inspired soft elastomeric pressure sensor with liquid metal-embedded microchannels

Abstract

Soft sensors are flexible and stretchable, and because of this, they can be used on a wide range of surfaces, regardless of their size or shape. Such sensors may have applications such as in human–robot interaction, healthcare, soft robotics and human motion detection, where they can sense their surroundings and provide information. In this work, a soft piezoresistive sensor inspired by human finger ridges has been fabricated with liquid metal (EGaIn) electrode-filled embedded microchannels on elastomeric material (Ecoflex 0030) and characterized for a pressure range of 0 to 280 kPa at different compression rates. The sensitivity of the elastomeric sensor increases and the limit of detection (LOD) decreases with a reduction in compression rate. In this work, microchannels on soft and stretchable elastomers are cast on a metallic mold prepared using the micromilling method. This method reduces the complexity of developing microchannels on the soft material using the metallic mold. The sensor has microchannels with a cross-section of 200 μm × 200 μm, an active sensing area of 10 × 10 mm² and overall dimensions of 15 × 15 × 2 mm³. At a low compression rate, this sensor exhibits a maximum sensitivity of 0.126 kPa⁻¹ and a high linearity of 0.98, a LOD of 68 Pa, a response time of 30 ms and stability for 10 000 consecutive cycles at 100 kPa load. The developed sensor was shown to successfully differentiate various objects (soft to hard) based on the feedback it received when it was deployed on the gripper of an industrial manipulator. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.