Broadband Multi-frequency PMUT Arrays for Miniature Photoacoustic Sensing

Broadband Multi-frequency PMUT Arrays for Miniature Photoacoustic Sensing | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Broadband Multi-frequency PMUT Arrays for Miniature Photoacoustic Sensing Yipeng Lu, Yexing Fang, Mengyue Zhang, Aocheng Bao, Chong Yang, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7276611/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Continuous and cuffless blood-pressure (BP) monitoring has attracted considerable attention in recent decades. Photoacoustic (PA) technology, which offers high vascular selectivity and encodes vessel diameter intrinsically, estimates BP by measuring vessel diameter and converting it to pressure, showing great promise. Here, we present miniature (2.5 mm × 5 mm) piezoelectric micromachined ultrasonic transducer (PMUT) arrays with tri-band operation that optimizes the depth–resolution trade-off in PA vascular sensing. The high-fill-factor, hexagonal-cavity PMUT arrays were fabricated via a cavity silicon-on-insulator (CSOI) process and exhibited broadband responses centered at ~ 3.5 MHz, 5.5 MHz, and 11 MHz, with − 6 dB fractional bandwidths of 126%, 103%, and 110%, respectively. This multi-frequency design balances sensitivity and resolution: low-frequency elements yield high sensitivity (noise-equivalent pressure, NEP of 2.9 \(\:mPa/\sqrt{Hz}\) at 3.5 MHz) for detecting deep vessels, while high-frequency elements resolve sub-millimeter vessels. Using ~ 5 \(\:\mu\:\) J 532 nm laser pulses, the system is able to successfully detect a 1 mm diameter vessel phantom at a depth of 5 mm in an optically clear medium. The vessel diameter was extracted from the temporal separation between wall echoes and matched theoretical predictions. Vessel phantoms were detected successfully at depths up to 40 mm in clear media and up to 6 mm in a tissue-mimicking phantom. This approach offers high spatial resolution together with extended penetration depth, demonstrating the feasibility of integrating multi-frequency PMUT arrays into compact PA systems. This work represents a significant step toward miniature photoacoustic sensing systems that are suitable for wearable, real-time, cuffless BP monitoring. Physical sciences/Engineering Physical sciences/Physics Full Text Additional Declarations There is no conflict of interest Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7276611","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":497692321,"identity":"26f070cd-f9b3-4b28-8a4b-1f4a241a7d9a","order_by":0,"name":"Yipeng 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Photoacoustic (PA) technology, which offers high vascular selectivity and encodes vessel diameter intrinsically, estimates BP by measuring vessel diameter and converting it to pressure, showing great promise. Here, we present miniature (2.5 mm \u0026times; 5 mm) piezoelectric micromachined ultrasonic transducer (PMUT) arrays with tri-band operation that optimizes the depth\u0026ndash;resolution trade-off in PA vascular sensing. The high-fill-factor, hexagonal-cavity PMUT arrays were fabricated via a cavity silicon-on-insulator (CSOI) process and exhibited broadband responses centered at ~\u0026thinsp;3.5 MHz, 5.5 MHz, and 11 MHz, with \u0026minus;\u0026thinsp;6 dB fractional bandwidths of 126%, 103%, and 110%, respectively. This multi-frequency design balances sensitivity and resolution: low-frequency elements yield high sensitivity (noise-equivalent pressure, NEP of 2.9 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:mPa/\\sqrt{Hz}\\)\u003c/span\u003e\u003c/span\u003e at 3.5 MHz) for detecting deep vessels, while high-frequency elements resolve sub-millimeter vessels. Using\u0026thinsp;~\u0026thinsp;5 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\mu\\:\\)\u003c/span\u003e\u003c/span\u003eJ 532 nm laser pulses, the system is able to successfully detect a 1 mm diameter vessel phantom at a depth of 5 mm in an optically clear medium. The vessel diameter was extracted from the temporal separation between wall echoes and matched theoretical predictions. Vessel phantoms were detected successfully at depths up to 40 mm in clear media and up to 6 mm in a tissue-mimicking phantom. This approach offers high spatial resolution together with extended penetration depth, demonstrating the feasibility of integrating multi-frequency PMUT arrays into compact PA systems. This work represents a significant step toward miniature photoacoustic sensing systems that are suitable for wearable, real-time, cuffless BP monitoring.\u003c/p\u003e","manuscriptTitle":"Broadband Multi-frequency PMUT Arrays for Miniature Photoacoustic Sensing","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-13 16:31:50","doi":"10.21203/rs.3.rs-7276611/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cfa9e81d-2881-4517-b778-38198e22bfe5","owner":[],"postedDate":"August 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":53125274,"name":"Physical sciences/Engineering"},{"id":53125275,"name":"Physical sciences/Physics"}],"tags":[],"updatedAt":"2025-10-22T06:15:34+00:00","versionOfRecord":[],"versionCreatedAt":"2025-08-13 16:31:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7276611","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7276611","identity":"rs-7276611","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}