A Soft Three-Axis Load Cell Using Liquid-Filled Three-Dimensional Microchannels in a Highly Deformable Elastomer

The advances in soft robotics have increased the need of soft sensors in various applications involved with physical interactions between humans and robots. In this letter, we propose a soft multiaxis force sensor made of multimaterial elastomer layers and embedded microfluidic channels that are sensitive to compression perpendicular to the channel length. The microchannels are geometrically divided into multiple segments for detecting forces in three axes. When a force is applied to the top surface of the sensor, the microchannels are compressed by multisegmented force plates made of rigid plastic. While the microchannels located on the sides in the structure detect shear forces, the microchannel at the bottom detects normal force. The three-dimensional configuration of the microchannel physically separates the side channels from the bottom channel and consequently enables mechanical decoupling of shear forces from normal force. The letter describes the design and fabrication of the proposed sensor and discusses the experimental results for sensor characterization.