UC San Diego

AbstractSports coaches help athletes develop and improve their skills by assessing their ability to perform motion primitives that make up functional sports tasks. Sports coaching today is mostly done visually, which demands constant attention and can be imprecise. While sensors like electronic textiles and surface electromyography can measure muscle engagement, they are susceptible to movement artifacts and noise due to surface electrode issues. Therefore, the work reported here focuses on our development of self-adhesive, fabric-based sensors that can be directly affixed onto skin for monitoring skin-strains and distributed muscular engagement during functional movements. The vision is that these sensors can be readily used by sports coaches and individuals to better assess motion primitives and the execution of sports tasks. The approach integrates piezoresistive graphene nanosheet thin films with kinesiology tape (K-Tape). Because every location of the film is responsive to strains, electrodes can also be judiciously placed along the nanocomposite for distributed strain sensing. Nanocomposite or “Smart K-Tape” sensors were fabricated, and electromechanical tests were conducted to characterize their tensile, compressive, and cyclic sensing properties. Upon confirming their linearity, repeatability, stability, and high sensitivity, individuals wore Smart K-Tape sensors over different muscle groups as they performed prescribed exercise and stretching movements. The Smart K-Tapes outputted unique waveforms that revealed the speed and duration of muscular engagement through movement sequences. Furthermore, the region of muscular contraction could also be localized using each Smart K-Tape as a distributed strain sensor, which demonstrated promise as a convenient and quantitative motion primitive assessment tool relevant for sports coaching and athletic skills development.