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A Flexible 2.45-GHz Power Harvesting Wristband with Net System Output from -24.3 dBm of RF Power

Research output: Contribution to journalArticle

Original languageEnglish
Article number7955016
Pages (from-to)380-395
Number of pages16
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number1
Early online date22 Jun 2017
DateAccepted/In press - 16 Apr 2017
DateE-pub ahead of print - 22 Jun 2017
DatePublished (current) - 1 Jan 2018


This paper presents a flexible 2.45-GHz wireless power harvesting wristband that generates a net dc output from a -24.3-dBm RF input. This is the lowest reported system sensitivity for systems comprising a rectenna and impedance-matching power management. A complete system has been implemented comprising: a fabric antenna, a rectifier on rigid substrate, a contactless electrical connection between rigid and flexible subsystems, and power electronics impedance matching. Various fabric and flexible materials are electrically characterized at 2.45 GHz using the two-line and the T-resonator methods. Selected materials are used to design an all-textile antenna, which demonstrates a radiation efficiency above 62% on a phantom irrespective of location, and a stable radiation pattern. The rectifier, designed on a rigid substrate, shows a best-in-class efficiency of 33.6% at -20 dBm. A reliable, efficient, and wideband contactless connection between the fabric antenna and the rectifier is created using broadside-coupled microstrip lines, with an insertion loss below 1 dB from 1.8 to over 10 GHz. A self-powered boost converter with a quiescent current of 150 nA matches the rectenna output with a matching efficiency above 95%. The maximum end-to-end efficiency is 28.7% at -7 dBm. The wristband harvester demonstrates net positive energy harvesting from -24.3 dBm, a 7.3-dB improvement on the state of the art.

    Research areas

  • Boost converter, fabric antenna, fabric-to-PCB connector, Internet of Things, power management, rectenna array, rectenna impedance matching, rectennas, RF energy harvesting, RF power transfer, smart fabric, T-resonator method, textile antenna, two-line method, Digital Health

    Structured keywords

  • Digital Health

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    Licence: CC BY


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