Highly Stretchable and Transparent Microfluidic Strain\nSensors for Monitoring Human Body Motions

Abstract

We report a new class of simple microfluidic strain sensors with\nhigh stretchability, transparency, sensitivity, and long-term stability\nwith no considerable hysteresis and a fast response to various deformations\nby combining the merits of microfluidic techniques and ionic liquids.\nThe high optical transparency of the strain sensors was achieved by\nintroducing refractive-index matched ionic liquids into microfluidic\nnetworks or channels embedded in an elastomeric matrix. The microfluidic\nstrain sensors offer the outstanding sensor performance under a variety\nof deformations induced by stretching, bending, pressing, and twisting\nof the microfluidic strain sensors. The principle of our microfluidic\nstrain sensor is explained by a theoretical model based on the elastic\nchannel deformation. In order to demonstrate its capability of practical\nusage, the simple-structured microfluidic strain sensors were performed\nonto a finger, wrist, and arm. The highly stretchable and transparent\nmicrofluidic strain sensors were successfully applied as potential\nplatforms for distinctively monitoring a wide range of human body\nmotions in real time. Our novel microfluidic strain sensors show great\npromise for making future stretchable electronic devices.