{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T13:03:04Z","timestamp":1790686984441,"version":"4.1.0"},"reference-count":44,"publisher":"AIP Publishing","issue":"9","funder":[{"DOI":"10.13039\/501100001843","name":"Anusandhan National Research Foundation","doi-asserted-by":"publisher","award":["SRG\/2022\/000202"],"award-info":[{"award-number":["SRG\/2022\/000202"]}],"id":[{"id":"10.13039\/501100001843","id-type":"DOI","asserted-by":"publisher"}]},{"name":"DST National Quantum Mission","award":["DST\/QTC\/NQM\/QMD\/2024\/4"],"award-info":[{"award-number":["DST\/QTC\/NQM\/QMD\/2024\/4"]}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:p>The vibrating parallel-plate capacitor-based Kelvin probe (KP) technique is a well-established method for measuring the contact potential difference (CPD) between a sample and a reference material, widely used in surface science and device characterization. In the present work, a compact and low-cost KP system is developed using simple and easily accessible electronic components for ambient-condition CPD measurements. A 35\u00a0mm diameter piezoelectric buzzer plate is employed for periodic modulation of a metallic reference probe, providing a compact and mechanically rigid alternative to conventional solenoid-based modulation systems. The vibration-induced capacitive current is measured using a homemade transimpedance amplifier and processed using a microcontroller-based digital lock-in amplifier (D-LIA) implemented on a Teensy 4.1 platform, enabling amplitude and phase extraction through numerical mixing and low-pass filtering techniques. The piezoelectric modulation scheme further enables the implementation of a compact self-resonant driver circuit operating near 1.7\u00a0kHz, eliminating the need for an external function generator during normal operation. The developed system was experimentally validated through analog-to-digital calibration, capacitance measurements, phase-sensitive RC circuit analysis, and KP measurements on copper\u2013aluminum systems under ambient oxidation conditions, demonstrating a CPD resolution of \u223c10 mV (standard deviation) when operated with an external function generator and \u223c100 mV using the self-resonant driver. The modular architecture of the system also provides the possibility for future implementation in scanning-based surface potential mapping, scanning tunneling microscopy tip-approach protocols, low-frequency spectroscopy measurements, and other phase-sensitive low-signal detection applications. Detailed electronic circuits, digital signal processing methods, and hardware implementations are presented.<\/jats:p>","DOI":"10.1063\/5.0350475","type":"journal-article","created":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T12:38:53Z","timestamp":1790685533000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Microcontroller-based digital lock-in kelvin probe system using a self-resonant piezoelectric buzzer plate"],"prefix":"10.1063","volume":"97","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-8907-1095","authenticated-orcid":false,"given":"Shanmi D.","family":"Syntem","sequence":"first","affiliation":[{"name":"Surface and Interface Science Laboratory, Department of Physics, Indian Institute of Technology Bombay , Powai, Mumbai 400076,","place":["India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-1204-9655","authenticated-orcid":false,"family":"Pratheek","sequence":"additional","affiliation":[{"name":"Surface and Interface Science Laboratory, Department of Physics, Indian Institute of Technology Bombay , Powai, Mumbai 400076,","place":["India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-3702-7215","authenticated-orcid":false,"given":"Priyamedha","family":"Sharma","sequence":"additional","affiliation":[{"name":"Surface and Interface Science Laboratory, Department of Physics, Indian Institute of Technology Bombay , Powai, Mumbai 400076,","place":["India"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7305-1368","authenticated-orcid":false,"given":"M.","family":"Maniraj","sequence":"additional","affiliation":[{"name":"Surface and Interface Science Laboratory, Department of Physics, Indian Institute of Technology Bombay , Powai, Mumbai 400076,","place":["India"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2026,9,29]]},"reference":[{"key":"2026092908384569200_c1","doi-asserted-by":"publisher","first-page":"82","DOI":"10.1080\/14786449808621172","article-title":"V. 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