{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T21:48:13Z","timestamp":1786657693822,"version":"build-2736575974"},"reference-count":49,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T00:00:00Z","timestamp":1771891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62475204"],"award-info":[{"award-number":["62475204"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Hangzhou Science and Technology Development Project","award":["202204T04"],"award-info":[{"award-number":["202204T04"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Formaldehyde (H2CO) is a hazardous volatile organic compound widely present in indoor and industrial environments, and its real-time, highly sensitive detection is essential for environmental safety. However, existing detection techniques often face challenges in simultaneously achieving high sensitivity and long-term stability, and many conventional photoacoustic spectroscopy (PAS) systems rely strongly on low gas flow rates to suppress flow-induced noise, which limits their applicability for continuous online monitoring. In this work, an ultraviolet photoacoustic spectroscopy (UV-PAS)-based H2CO detection system operating in a nitrogen (N2) background is developed. The system integrates a compact differential photoacoustic cell (PAC) with a 320 nm ultraviolet laser source, in which the resonator length and buffer configuration are carefully optimized to enhance acoustic resonance and effectively suppress flow-related disturbances. Notably, a key innovation of this study is that the system maintains a stable photoacoustic response even under relatively high gas flow conditions. Experimental results demonstrate that at a flow rate of 250 sccm, the photoacoustic signal amplitude remains stable, and the noise level is well controlled, significantly reducing the dependence of conventional PAS systems on low-flow operation. The photoacoustic cell exhibits a resonant frequency of 1767 Hz and a quality factor of 46. Calibration using a 47.31 ppm H2CO:N2 gas mixture shows a good linear response with a correlation coefficient of R2 = 0.98844. The minimum detection limit reaches 2.50 ppm at a 1 s integration time and is further improved to 88.1 ppb at an integration time of 2202 s based on Allan\u2013Werle deviation analysis. These results demonstrate that the proposed UV-PAS system provides a sensitive, stable, and cost-effective solution for real-time trace H2CO detection while retaining robust performance at elevated gas flow rates, highlighting its strong potential for practical applications.<\/jats:p>","DOI":"10.3390\/s26051410","type":"journal-article","created":{"date-parts":[[2026,2,24]],"date-time":"2026-02-24T13:53:20Z","timestamp":1771941200000},"page":"1410","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["High-Flow-Rate Trace Formaldehyde Detection Based on Ultraviolet Photoacoustic Spectroscopy Using a Long Resonant Photoacoustic Cell"],"prefix":"10.3390","volume":"26","author":[{"given":"Qianjin","family":"Gan","sequence":"first","affiliation":[{"name":"School of Optoelectronic Engineering, Xidian University, Xi\u2019an 710071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhongqi","family":"Feng","sequence":"additional","affiliation":[{"name":"Xi\u2019an Institute of Applied Optics, Xi\u2019an 710065, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Deng","family":"Zhang","sequence":"additional","affiliation":[{"name":"Xi\u2019an Institute of Applied Optics, Xi\u2019an 710065, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shibang","family":"Ma","sequence":"additional","affiliation":[{"name":"Xi\u2019an Institute of Applied Optics, Xi\u2019an 710065, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiu","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Optoelectronic Engineering, Xidian University, Xi\u2019an 710071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4840-9529","authenticated-orcid":false,"given":"Xukun","family":"Yin","sequence":"additional","affiliation":[{"name":"School of Optoelectronic Engineering, Xidian University, Xi\u2019an 710071, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"100780","DOI":"10.1016\/j.pacs.2025.100780","article-title":"Ppb-Level Formaldehyde Sensor Utilizing a Compact 3D-Printed Differential Photoacoustic Cell and a 320 Nm UV Laser","volume":"46","author":"Yang","year":"2025","journal-title":"Photoacoustics"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1084","DOI":"10.1039\/D0AY02252G","article-title":"Recent Advances in Selective Formaldehyde Detection in Biological and Environmental Samples by Fluorometric and Colorimetric Chemodosimeters","volume":"13","author":"Manna","year":"2021","journal-title":"Anal. 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