Flexible and Wearable Thermoelectric Devices for Personal Cooling and Thermal Haptic Sensations

In this presentation, we will show our recent work on the design and fabrication of flexible and wearable thermoelectric devices (TEDs) for personal cooling and thermal haptic applications. First, a wearable personal cooling garment is developed based on flexible TEDs, which are solid-state refrigeration devices that can pump heat against a temperature difference and thus are suitable for personal cooling applications in hot environments. The flexible TEDs can make conformal contact with the skin to provide direct cooling without bulky heat sinks. The design of the individual TEDs and the garment system is optimized for the metabolic heat flux and environment thermal conditions. The garment is shown to maintain the skin temperature within its thermal comfort zone over a long duration in a hot environment of up to 40 ^oC under mild forced convection conditions. The garment can provide thermal comfort at even high ambient temperature with a more efficient heat sink. With the advantages of lightweight, flexible, controllable and long-term effective cooling, the TED cooling garments can contribute to enhancing human health in a hotter climate that is accompanied by increasing frequency, intensity, and duration of extreme heat events

Second, the flexible TEDs can offer heating and cooling with high spatial and temporal resolution, making them ideally suited for thermal haptic sensation, which is still absent compared to other common sensations (such as visual, audio, tactile) in virtual/augmented reality applications. We fabricated and integrated thin flexible TEDs (with a total thickness of less than 1 mm) that can make conformal contact with human skin and induce rapid heating and cooling (over 4 ^oC per second), surpassing the thermal detection threshold for strong sensations in human skin. By combining different operational strategies, we introduced complex thermal sensations, paving the way for potential real-time thermal haptic sensation in VR/AR applications.