RF-Powered Wearable Energy Harvesting and Storage Module Based on E-Textile Coplanar Waveguide Rectenna and Supercapacitor
This paper presents a high-efficiency compact (<inline-formula> <tex-math notation="LaTeX">$0.016\lambda _{0}^{2}$ </tex-math></inline-formula>) textile-integrated energy harvesting and storage module for RF power transfer. A flexible 50 <inline-formula> <t...
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| Autores principales: | , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
IEEE
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/ce108313dbc64d5abdcfc55f16162858 |
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| Sumario: | This paper presents a high-efficiency compact (<inline-formula> <tex-math notation="LaTeX">$0.016\lambda _{0}^{2}$ </tex-math></inline-formula>) textile-integrated energy harvesting and storage module for RF power transfer. A flexible 50 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula>-thick coplanar waveguide rectenna filament is integrated with a spray-coated supercapacitor to realize an “e-textile” energy supply module. The meandered antenna maintains an <inline-formula> <tex-math notation="LaTeX">$S_{11}< -6$ </tex-math></inline-formula> dB inside and outside the fabric and in human proximity with a 2.3 dBi gain. The rectifier achieves a peak RF-DC efficiency of 80%, across a 4.5 <inline-formula> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> load, and a 1.8 V open-circuit voltage from −7 dBm. The supercapacitor is directly spray-coated on a cotton substrate using carbon and an aqueous electrolyte. When connected to the supercapacitor, the rectifier achieves over an octave half-power bandwidth. The textile-integrated rectenna is demonstrated charging the supercapacitor to 1.5 V (8.4 mJ) in 4 minutes, at 4.2 m from a license-free source, demonstrating a significant improvement over previous rectennas while eliminating power management circuitry. The integrated module has an end-to-end efficiency of 38% at 1.8 m from the transmitter. On-body, the rectenna’s efficiency is 4.8%, inclusive of in-body losses and transient shadowing, harvesting 4 mJ in 32 seconds from 16.6 <inline-formula> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula>/cm<sup>2</sup>. It is concluded that e-textile rectennas are the most efficient method for powering wearables from <inline-formula> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula>/cm<sup>2</sup> power densities. |
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