{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T04:04:15Z","timestamp":1776744255946,"version":"3.51.2"},"reference-count":25,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,3,30]],"date-time":"2023-03-30T00:00:00Z","timestamp":1680134400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the German Research Foundation (DFG)","award":["492151098"],"award-info":[{"award-number":["492151098"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Sensors for industrial and structural health monitoring are often in shielded and hard-to-reach places. Acoustic wireless power transfer (WPT) and piezoelectric backscatter enable batteryless sensors in such scenarios. Although the low efficiency of WPT demands power-conserving sensor nodes, backscatter communication, which consumes near-zero power, has not yet been combined with WPT. This study reviews the available approaches to acoustic WPT and active and passive acoustic through-metal communication. We design a batteryless and backscattering tag prototype from commercially available components. Analysis of the prototypes reveals that low-power hardware poses additional challenges for communication, i.e., unstable and inaccurate oscillators. Therefore, we implement a software-defined receiver using digital phase-locked loops (DPLLs) to mitigate the effects of oscillator instability. We show that DPLLs enable reliable backscatter communication with inaccurate clocks using simulation and real-world measurements. Our prototype achieves communication at 2 kBs\u22121\u00a0over a distance of 3 m. Furthermore, during transmission, the prototype consumes less than 300\u00a0\u03bcW power. At the same time, over 4 mW of power is received through wireless transmission over a distance of 3 m with an efficiency of 2.8%.<\/jats:p>","DOI":"10.3390\/s23073617","type":"journal-article","created":{"date-parts":[[2023,3,31]],"date-time":"2023-03-31T02:08:01Z","timestamp":1680228481000},"page":"3617","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Acoustic Backscatter Communication and Power Transfer for Batteryless Wireless Sensors"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6936-2307","authenticated-orcid":false,"given":"Peter","family":"Oppermann","sequence":"first","affiliation":[{"name":"Hamburg University of Technology, TUHH, Institute for Autonomous Cyber-Physical Systems, 21073 Hamburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6936-6444","authenticated-orcid":false,"given":"Bernd-Christian","family":"Renner","sequence":"additional","affiliation":[{"name":"Hamburg University of Technology, TUHH, Institute for Autonomous Cyber-Physical Systems, 21073 Hamburg, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"15501477211067740","DOI":"10.1177\/15501477211067740","article-title":"Wireless power transfer and energy harvesting in distributed sensor networks: Survey, opportunities, and challenges","volume":"18","author":"Ijemaru","year":"2022","journal-title":"Int. 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