Wearable strain sensor for human motion detection based on ligand-exchanged gold nanoparticles

[Display omitted] •A wearable strain sensor based on thin films of ligand-exchanged gold nanoparticles was fabricated.•Effects of particle size, ligand chain length, number of layers and substrate thickness on sensing performance were examined.•The sensor was able to detect strain as small as 0.075% with gauge factor of 26.•The prototype sensor fabricated on polydimethylsiloxane substrate was successfully used to detect motions of finger and wrist. A wearable strain sensor consisting thin films of organic ligand-exchanged gold nanoparticles (Au NPs) was fabricated and optimized by tuning particle size, ligand chain length, number of layers and substrate thickness. The thin films of 5 layers of 8-mercaptooctanoic acid-exchanged Au NPs with size of 9nm deposited on polydimethylsiloxane substrate exhibited the best performance with excellent gauge factor, high sensitivity, and good reproducibility. The sensor was able to monitor human motions induced by finger and wrist movements. In addition to facile fabrication, this prototype version of wearable strain sensor appears to be practically feasible for the detection of minute human motions.