Laser Sintered Silver Nanoparticles on the PDMS for a Wearable Strain Sensor Capable of Detecting Finger Motion

A wearable strain sensor was fabricated by sintering silver (Ag) nanoparticles (NPs) with an ultraviolet laser on a semicured poly­(dimethylsiloxane) (PDMS) substrate. The semicured PDMS enabled the NPs to effectively penetrate through the PDMS surface, resulting in a thick layer with a sintered conductive pattern that contributed to reliable and stable resistive responses upon application of mechanical strain. Microstructures and cross sections of the laser-sintered NPs were investigated with varying laser power and scan speeds during the sintering process. A sensing mechanism is proposed based on the findings. The electromechanical responses of the strain sensors were characterized in terms of the process conditions. The response times and long-term cyclic responses of the strain sensors were evaluated. Finally, a wearable strain sensor was designed and fabricated for the detection of various finger and hand motions. A series of experimental demonstrations are presented that capture various gestures and grasping motions of the fingers according to the sensor prototype. The techniques and results of this research will aid the future development of flexible sensors, wearable devices, and related engineering and scientific applications.