Energy Harvesting from the Human Body

To improve thermal energy harvesting from the body, a complex set of microclimates, components, and functions must be considered in relation to each other. While many energy harvesting improvements highlight the importance of device and material optimization, little focus has been geared towards improving the collective textile-electronic as a whole. The objective of this project is to integrate thermal energy harvesters into a knit textile and to make a power generation map for locations and activity scenarios from thermal energy harvesting on the body. A test method for evaluating the performance of a TEG in a wearable form is developed and demonstrated using both in-lab and out-of-lab procedures. The fabrication procedure developed in this project demonstrates a method of integrating rigid devices into a flexible substrate. The wearable device is used in a human trial to study energy harvesting during series of activities in different environmental conditions.

We use finite-element simulations explore how convection and conduction change the heat flux through the textile and the thermoelectric generator (TEG). This project shows which knit properties improve thermal energy harvesting by modifying the environment immediately surrounding the TEG using these simulations. These simulations provide guidance on critical design considerations for integrating wearable technology with knit textiles. Textile swatches were knit and characterized accordingly for validation of the simulation results. The research shows the significant effect of stitch density on air permeability of the textile and corresponding heat flow induced by convection.

The results from the simulations led to the design of a knitted shirt with structured stitches that promote energy harvesting. The shirt is used in a human trial, which covered a series of activities in different environmental conditions. The results of these trials confirm the influence of convection on thermal energy harvesting in addition to mapping energy harvesting levels over the torso. As wearable technology advances, this work can be referenced as a foundation for investigating textile design based on human factors and device functionality.