Investigation of a cantilever structured piezoelectric energy harvester used for wearable devices with random vibration input

•A piezoelectric energy harvester used for human motion energy harvesting.•Energy harvesting capability of using a linear harvester in random vibration input.•Performance tested in real-life activities in hand-arm and head motions.•Output power enough to drive medical sensors in real applications.•Guidance to help designers to balance the choice of a linear and nonlinear systems in energy harvesters. The capability of using a linear kinetic energy harvester – A cantilever structured piezoelectric energy harvester – to harvest human motions in the real-life activities is investigated. The whole loop of the design, simulation, fabrication and test of the energy harvester is presented. With the smart wristband/watch sized energy harvester, a root mean square of the output power of 50 μW is obtained from the real-life hand-arm motion in human’s daily life. Such a power is enough to make some low power consumption sensors to be self-powered. This paper provides a good and reliable comparison to those with nonlinear structures. It also helps the designers to consider whether to choose a nonlinear structure or not in a particular energy harvester based on different application scenarios.