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A wearable energy harvester (EH) incorporating a face mask with a thermoelectric generator is demonstrated. The function of this device is to generate electrical power from the heat produced by the human body, particularly breath, with the specific aim of powering wearable sensor applications. A prototype was built using a commercially available N95 face mask, a thermoelectric generator, and a heatsink. The performance of this EH device was assessed using experimental and numerical methodologies. The experimentally tested power output of the prototype was found to be ≈100 µW, with a corresponding power density of ≈30 µW/cm3, for a temperature difference of 7°C. [ABSTRACT FROM AUTHOR]

The purpose of this work is to demonstrate a new simple stand-alone method of characterizing the impedance of a pyroelectric cell. This method utilizes a pyroelectric single pole low-pass filter technique. Utilizing the properties of a pyroelectric single pole low-pass filter technique, a known input voltage is applied and using simple equations, capacitance Cp and resistance Rp at a frequency range of 1 mHz to 1 Hz can be calculated. For verification purposes, an LCR meter and an impedance analyzer were exploited at 10 and 100 Hz, respectively. Results showed that Rp values for two materials, lead zirconate titanate-5A and polyvinylidene difluoride, were within 8%, and Cp values were within 7.5%. In addition, to verify the importance of the impedance values in energy harvesting applications, output power was measured with varying impedance values. The optimal load resistances for polyvinylidene difluoride and lead zirconate titanate- 5A were consistent with the measured pyroelectric impedance at the particular heat range with 10.9% and 1.4%, respectively. The pyroelectric single pole low-pass filter method presented here demonstrates that for pyroelectric materials the impedance depends on two major factors: (1) average working temperature and (2) the heating rate. Neglecting these two factors can result in inefficient and unpredictable behavior of pyroelectric materials when used in energy harvesting applications. [ABSTRACT FROM AUTHOR]

Fluctuating heat radiating from the environment is an unused and unknown source. This study investigates pyroelectric energy harvesting as a way to tap a fluctuating radiation heat source. Appropriate circuitry coupling and the frequency of the radiation source play a key role in the ability to harvest this energy. Hence, a design of experiment approach that limits factors to temperature change frequency, electrical resistance, and capacitance is utilized to develop a full-factorial model at three levels for each factor. In order to quantify and maximize the harvested energy, a response surface model was developed. The optimum values for temperature change frequency, resistance, and capacitance were predicted to be 0.05 Hz, 7330 kΩ, and 100 µF, respectively, for a PZT-5A sample with a volume of 0.684 cm3. The maximum response of 62.89 µJ was predicted for the optimum values. [ABSTRACT FROM AUTHOR]