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Download as PDFWearable Thermoelectric Generators
There exists great interest in the utilization of the human body as a possible power supply for running such electronics as medical monitoring devices and sensors. This project details the effective utilization of a new type of form-fitting, wearable, wristband thermoelectric heat sink, Figure 1, which relies on 2D heat-spreading for dissipating heat from the cold side of the TEG for the purposes of energy harvesting. The performance of the TEG/heat sink systems is limited by (1) the small working temperature differential between the body and ambient temperature; (2) the desire to use natural air convection cooling on the cold-side of the generator; and (3) the requirement for thin, light-weight systems that are comfortable for long-term use. The 2D heat-spreading wristbands produce 285 μW from a Bi2Te3 TEG module (256 thermocouples, each is 2 mm in thickness and 1 mm2 in area). The large available surface area of the wristband as well as the highly thermally conductive nature of copper ensures effective cooling of the cold side and allows heat to spread and dissipate throughout the wristband, thereby enhancing the effective heat transfer coefficient. A 75-minute field test was conducted that measured the voltage output from the TEG as well as the temperature difference across the module when worn on the upper forearm. In addition, the output of the TEG was connected to a commercially available DC-DC converter, which boosted the voltage to a steady 4.15 V, shown in Figure 2, allowing for coupling with external applications such as EKG chips and pulse oximeters.
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- Figure 1: A model of the wearable, wristband heat-sink. The heat-sink differs from other wearable heat-sinks in that 2D heat-spreading is utilized for effective cooling of the cold side of the TEG. The TEG/heat-sink system has a maximum thickness of 5 mm.
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- Figure 2: A 75-minute field test of the TEG/wristband system. In addition to measuring the open circuit voltage and temperature differential across the module, we also measured the output from a commercially available DC-DC converter. In particular, the output from the DC-DC converter showed a steady 4.15 V during the duration of the test.
