Wearable and implantable devices are currently used for a variety of functions, including health tracking and monitoring.    However, supplying energy usually requires cumbersome batteries and downtime due to recharging.    Now, an international team of researchers suggests that advances in materials and electronic design may be able to convert biomechanical energy into electric energy, paving the way for devices that can be worn and implanted but do not require constant recharging, according to Larry Cheng, Dorothy Quiggle Career Development professor in the Department of Engineering Science and Mechanics and an affiliate of the Institute for Computational and Data Sciences.   "In this particular review, we are looking at possible energy supply without the need for batteries and other components, so it's of particular interest to create these energy harvesters for self-powered devices or ones that could also be used t