Harvesting Temperature Fluctuations as Electrical Energy Using Torsional and Tensile Polymer Muscles



Diverse means have been deployed for harvesting electrical energy from mechanical actuation produced by low-grade waste heat, but cycle rate, energy-per-cycle, device size and weight, or cost have limited applications. We report the electromagnetic harvesting of thermal energy as electrical energy using thermally powered torsional and tensile artificial muscles made from inexpensive polymer fibers used for fishing line and sewing thread. We show that a coiled 27 μm-diameter nylon muscle fiber can be driven by 16.7 ⁰C air temperature fluctuations to spin a magnetic rotor to a peak torsional rotation speed of 70000 rpm for over 300000 heating-cooling cycles without performance degradation. By employing resonant fluctuations in air temperature of 19.6 ⁰C, an average output electrical power of 124 W per kg of muscle was realized. Using tensile actuation of polyethylene-based coiled muscles and alternating flows of hot and cold water, up to 1.4 J of electrical energy was produced per cycle. The corresponding per cycle electric energy and peak power output, per muscle weight, were 77 J kg⁻¹ and 28 W kg⁻¹, respectively.


Supplemental information is included.


Chemistry, Refuse as fuel, Engineering, Environmental sciences, Ecology, Polymers


This work was supported by the Creative Research Initiative Center for Self-powered Actuation and the Korea–US Air Force Cooperation Program Grant No. 2013K1A3A1A32035592 in Korea. Support at the University of Texas at Dallas was provided by Air Force Office of Scientific Research grants FA9550-15-1-0089, FA9550- 14-1-0227, and FA2386-13-1-4119, NASA grants NNX14CS09P and NNX15CS05C, NSF grant CMMI 1120382, and the Robert A. Welch Foundation grant AT-0029. Additional support was from the Australian Research Council Discovery Grant DP110101073 and the Australian National Fabrication Facility, and a Natural Sciences and Engineering Research Council of Canada Discovery grant.


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