{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,20]],"date-time":"2026-03-20T13:20:11Z","timestamp":1774012811307,"version":"3.50.1"},"reference-count":46,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2017,9,12]],"date-time":"2017-09-12T00:00:00Z","timestamp":1505174400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents a miniaturized Doppler radar that can be used as a motion sensor for low-cost Internet of things (IoT) applications. For the first time, a radar front-end and its antenna are integrated on a multilayer cellulose-based substrate, built-up by alternating paper, glue and metal layers. The circuit exploits a distributed microstrip structure that is realized using a copper adhesive laminate, so as to obtain a low-loss conductor. The radar operates at 24 GHz and transmits 5 mW of power. The antenna has a gain of 7.4 dBi and features a half power beam-width of 48 degrees. The sensor, that is just the size of a stamp, is able to detect the movement of a walking person up to 10 m in distance, while a minimum speed of 50 mm\/s up to 3 m is clearly measured. Beyond this specific result, the present paper demonstrates that the attractive features of cellulose, including ultra-low cost and eco-friendliness (i.e., recyclability and biodegradability), can even be exploited for the realization of future high-frequency hardware. This opens opens the door to the implementation on cellulose of devices and systems which make up the \u201csensing layer\u201d at the base of the IoT ecosystem.<\/jats:p>","DOI":"10.3390\/s17092090","type":"journal-article","created":{"date-parts":[[2017,9,12]],"date-time":"2017-09-12T10:40:04Z","timestamp":1505212804000},"page":"2090","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["A 24-GHz Front-End Integrated on a Multilayer Cellulose-Based Substrate for Doppler Radar Sensors"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4523-2193","authenticated-orcid":false,"given":"Federico","family":"Alimenti","sequence":"first","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8184-8297","authenticated-orcid":false,"given":"Valentina","family":"Palazzi","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chiara","family":"Mariotti","sequence":"additional","affiliation":[{"name":"Infineon Technologies Austria AG, Siemensstrasse 2, 9500 Villach, Austria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marco","family":"Virili","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Giulia","family":"Orecchini","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6485-393X","authenticated-orcid":false,"given":"Stefania","family":"Bonafoni","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Luca","family":"Roselli","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paolo","family":"Mezzanotte","sequence":"additional","affiliation":[{"name":"Department of Engineering, University of Perugia, 06125 Perugia, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2017,9,12]]},"reference":[{"key":"ref_1","unstructured":"Manyika, J., Chui, M., Bughin, J., Dobbs, R., Bisson, P., and Marrs, A. 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