{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,14]],"date-time":"2026-10-14T01:48:30Z","timestamp":1791942510202,"version":"4.3.4"},"reference-count":44,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T00:00:00Z","timestamp":1768867200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000780","name":"European Commission","doi-asserted-by":"publisher","award":["883116"],"award-info":[{"award-number":["883116"]}],"id":[{"id":"10.13039\/501100000780","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Real-tIme on-site forenSic tracE qualificatioN (RISEN) project"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this work we report the results of analysis of the acoustic signal generated by the interaction of a nanosecond laser pulse (30 mJ, 1064 nm) with various residues placed on a silica wafer. The signal was captured by a unidirectional microphone placed 30 mm from the laser-generated plasma. The examined sample classes, other than the clean wafer, included particles from soils and rocks, carbonates, nitro precursors, ash, coal, smeared diesel, and particles of explosives. We tested three types of explosives, namely PETN, RDX, and HMX, having different origins. For the explosives, the acoustic signal showed a faster rise, larger amplitude, different width, and attenuation compared with the other sample classes. By subtracting the acoustic signal from the wafer at the same position, obtained after four cleaning laser pulses, the contribution of echoes was eliminated and true differences between the residue and substrate became evident. Through four different features in the subtracted signal, it was possible to classify explosives without the presence of false positives; the estimated limit of detection was 15 ng, 9.6 ng, and 18 ng for PETN, RDX, and HMX, respectively, where the mass was extrapolated from nano-printed samples and LIBS spectra acquired simultaneously. Furthermore, HMX was distinguished from the other two explosives in 90% of the cases; diesel and coal were also recognized. We also found that explosives deposited through wet transfer behaved as inert substances for the tested masses up to 30 ng.<\/jats:p>","DOI":"10.3390\/s26020672","type":"journal-article","created":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T09:24:34Z","timestamp":1768901074000},"page":"672","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Acoustic Signatures in Laser-Induced Plasmas for Detection of Explosives in Traces"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0823-0359","authenticated-orcid":false,"given":"Violeta","family":"Lazic","sequence":"first","affiliation":[{"name":"Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratory NUC-TECFIS-DIM, Via Enrico Fermi 45, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6437-4015","authenticated-orcid":false,"given":"Biljana","family":"Stankov","sequence":"additional","affiliation":[{"name":"Institute of Physics Belgrade, University of Belgrade, 11080 Belgrade, Serbia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4250-4699","authenticated-orcid":false,"given":"Fabrizio","family":"Andreoli","sequence":"additional","affiliation":[{"name":"Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratory NUC-FUSEN-TEN, Via Enrico Fermi 45, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marco","family":"Pistilli","sequence":"additional","affiliation":[{"name":"Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratory NUC-TECFIS-DIM, Via Enrico Fermi 45, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ivano","family":"Menicucci","sequence":"additional","affiliation":[{"name":"Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratory NUC-TECFIS-DIM, Via Enrico Fermi 45, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0004-3507-0348","authenticated-orcid":false,"given":"Christian","family":"Ulrich","sequence":"additional","affiliation":[{"name":"Fraunhofer Institute for Chemical Technology ICT, Energetic Materials Department, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Frank","family":"Schn\u00fcrer","sequence":"additional","affiliation":[{"name":"Fraunhofer Institute for Chemical Technology ICT, Energetic Materials Department, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roberto","family":"Chirico","sequence":"additional","affiliation":[{"name":"Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Laboratory NUC-TECFIS-DIM, Via Enrico Fermi 45, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0861-558X","authenticated-orcid":false,"given":"Pasqualino","family":"Gaudio","sequence":"additional","affiliation":[{"name":"Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Roma, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,20]]},"reference":[{"key":"ref_1","first-page":"656","article-title":"Chemical classification of explosives","volume":"51","author":"Zapata","year":"2021","journal-title":"Crit. Rev. Anal. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.trac.2012.09.010","article-title":"The vapor pressures of explosives","volume":"42","author":"Ewing","year":"2013","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Marshall, M., and Oxley, J.C. (2009). Analysis and detection of explosives by mass spectrometry. Aspects of Explosives Detection, Elsevier.","DOI":"10.1016\/B978-0-12-374533-0.00002-7"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/S0021-9673(03)00305-4","article-title":"Modern developments in gas chromatography\u2013mass spectrometry-based environmental analysis","volume":"1000","author":"Santos","year":"2003","journal-title":"J. Chromatogr. A"},{"key":"ref_5","first-page":"1727","article-title":"Trends in environmental monitoring of high explosives present in soil\/sediment\/groundwater using LC\u2013MS\/MS","volume":"42","author":"Sharma","year":"2022","journal-title":"Mass Spectrom. Rev."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1007\/s00216-013-7316-0","article-title":"Direct analysis in real time\u2014A critical review on DART-MS","volume":"406","author":"Gross","year":"2014","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"100233","DOI":"10.1016\/j.forc.2020.100233","article-title":"Practical investigation of direct analysis in real time mass spectrometry for fast screening of explosives","volume":"18","author":"Frazier","year":"2020","journal-title":"Forensic Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1016\/S0039-9140(00)00565-8","article-title":"A critical review of ion mobility spectrometry for the detection of explosives and explosive-related compounds","volume":"54","author":"Ewing","year":"2001","journal-title":"Talanta"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Kagan, A., and Oxley, J.C. (2022). Trace detection of explosives by ion mobility spectrometry. Counterterrorist Detection Techniques of Explosives, Elsevier. [2nd ed.].","DOI":"10.1016\/B978-0-444-64104-5.00012-6"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/j.trac.2013.10.011","article-title":"Infrared and Raman spectroscopy techniques applied to identification of explosives","volume":"54","year":"2014","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1007\/s11082-022-03631-w","article-title":"Raman spectroscopic and advanced signal processing analyses for real-time standoff detection and identification of explosives","volume":"54","author":"Abdallah","year":"2022","journal-title":"Opt. Quantum Electron."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Lazic, V., Palucci, A., De Dominicis, L., Nuvoli, M., Pistilli, M., Menicucci, I., Colao, F., and Almaviva, S. (2019). Integrated laser sensor (ILS) for remote surface analysis: Application for detecting explosives in fingerprints. Sensors, 19.","DOI":"10.3390\/s19194269"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1509","DOI":"10.1111\/1556-4029.70038","article-title":"Assessment of handheld Raman spectroscopy for forensic analysis of dark-colored bulk explosive fuel\u2013oxidizer mixtures","volume":"70","author":"Logrado","year":"2025","journal-title":"J. Forensic Sci."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"166","DOI":"10.1016\/j.trac.2018.03.018","article-title":"Explosive detection by surface-enhanced Raman scattering","volume":"105","author":"Gillibert","year":"2018","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1021\/acs.analchem.5b04131","article-title":"Review of surface-enhanced Raman scattering applications in forensic science","volume":"88","author":"Muehlethaler","year":"2016","journal-title":"Anal. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"210048","DOI":"10.29026\/oea.2021.210048","article-title":"Flexible SERS substrates for hazardous materials detection: Recent advances","volume":"4","author":"Bharati","year":"2021","journal-title":"Opto-Electron. Adv."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"106025","DOI":"10.1016\/j.microc.2021.106025","article-title":"Emerging strategies for enhancing detection of explosives by artificial olfaction","volume":"164","author":"Wasilewski","year":"2021","journal-title":"Microchem. J."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2499","DOI":"10.1063\/1.1771493","article-title":"Instrumentation for trace detection of high explosives","volume":"75","author":"Moore","year":"2004","journal-title":"Rev. Sci. Instrum."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1016\/j.talanta.2011.11.043","article-title":"Current trends in explosive detection techniques","volume":"88","author":"Caygill","year":"2012","journal-title":"Talanta"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"10804","DOI":"10.1021\/acsnano.0c01579","article-title":"Recent developments in the field of explosive trace detection","volume":"14","author":"Parkin","year":"2020","journal-title":"ACS Nano"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"670","DOI":"10.1016\/j.fsisyn.2020.01.020","article-title":"Interpol review of detection and characterization of explosives and explosives residues 2016\u20132019","volume":"2","author":"Klapec","year":"2020","journal-title":"Forensic Sci. Int. Synergy"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e00261","DOI":"10.1016\/j.teac.2025.e00261","article-title":"Recent innovations in explosive trace detection: Advances and emerging technologies","volume":"46","author":"Nabat","year":"2025","journal-title":"Trends Environ. Anal. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Augustyniak, D., and Szala, M. (2025). Field explosives detectors\u2014Current status and development prospects. Sensors, 25.","DOI":"10.3390\/s25196024"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Lazic, V., Andreoli, F., Almaviva, S., Pistilli, M., Menicucci, I., Ulrich, C., Schn\u00fcrer, F., and Chirico, R. (2024). A novel LIBS sensor for sample examinations on a crime scene. Sensors, 24.","DOI":"10.3390\/s24051469"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"6148","DOI":"10.1364\/AO.42.006148","article-title":"Laser-induced breakdown spectroscopy analysis of energetic materials","volume":"42","author":"Harmon","year":"2003","journal-title":"Appl. Opt."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"283","DOI":"10.1007\/s00216-009-2802-0","article-title":"Laser-induced breakdown spectroscopy for detection of explosives residues","volume":"395","author":"Gottfried","year":"2009","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1028","DOI":"10.1016\/j.sab.2009.07.035","article-title":"Analysis of explosive and other organic residues by laser-induced breakdown spectroscopy","volume":"64","author":"Lazic","year":"2009","journal-title":"Spectrochim. Acta B"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"644","DOI":"10.1016\/j.sab.2011.07.003","article-title":"Detection of explosives in traces by laser-induced breakdown spectroscopy","volume":"66","author":"Lazic","year":"2011","journal-title":"Spectrochim. Acta B"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1445","DOI":"10.1039\/c0ja00188k","article-title":"Analysis of explosive residues in human fingerprints using optical catapulting\u2013laser-induced breakdown spectroscopy","volume":"26","author":"Abdelhamid","year":"2011","journal-title":"J. Anal. At. Spectrom."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.talanta.2013.02.026","article-title":"Recognition of explosives fingerprints using machine learning and LIBS","volume":"110","author":"Moros","year":"2013","journal-title":"Talanta"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"117197","DOI":"10.1016\/j.trac.2023.117197","article-title":"Recent advances in LIBS for explosive analysis","volume":"166","author":"Ding","year":"2023","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1840","DOI":"10.1021\/acs.analchem.1c04792","article-title":"LIBS-acoustic fusion for mineral differentiation","volume":"94","author":"Purohit","year":"2022","journal-title":"Anal. Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"107140","DOI":"10.1016\/j.sab.2025.107140","article-title":"Acoustic signal in overcoming the matrix effect in LIBS","volume":"226","author":"Moros","year":"2025","journal-title":"Spectrochim. Acta B"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1007\/s00340-021-07626-5","article-title":"Determination of calorific value in coal by LIBS with acoustic normalization","volume":"127","author":"Lu","year":"2021","journal-title":"Appl. Phys. B"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1007\/s00193-023-01149-y","article-title":"Shock wave scaling","volume":"33","author":"Hargather","year":"2023","journal-title":"Shock. Waves"},{"key":"ref_36","unstructured":"Gottfried, J.L. (2014). New Laboratory-Scale Method for the Determination of Explosive Performance from Laser-Induced Shock Waves, U.S. Army Research Laboratory. ARL-TR-6844."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1080\/07370652.2023.2200442","article-title":"Laser-induced air shock from energetic materials (LASEM)","volume":"43","author":"Gottfried","year":"2023","journal-title":"J. Energ. Mater."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"9054","DOI":"10.1364\/AO.55.009054","article-title":"Use of photoacoustic excitation and laser vibrometry for remote explosives detection","volume":"55","author":"Wynn","year":"2016","journal-title":"Appl. Opt."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"28","DOI":"10.1016\/j.sab.2017.09.001","article-title":"Calibration approach for extremely variable laser induced plasmas and a strategy to reduce the matrix effect in general","volume":"137","author":"Lazic","year":"2017","journal-title":"Spectrochim. Acta B"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"105765","DOI":"10.1016\/j.sab.2020.105765","article-title":"Quantification of heavy metals in oils with \u03bcL volume by laser induced breakdown spectroscopy and minimazing of the matrix effect","volume":"164","author":"Aruffo","year":"2020","journal-title":"Spectrochim. Acta Part B"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1007\/s00193-025-01227-3","article-title":"Acoustic measurements of laser-induced microshocks: Time of arrival to yield estimations","volume":"35","author":"Wainwright","year":"2025","journal-title":"Shock Waves"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"4718","DOI":"10.1364\/OE.449382","article-title":"Determination of detonation characteristics by laser-induced plasma spectra and micro-explosion dynamics","volume":"30","author":"Wang","year":"2022","journal-title":"Opt Express."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"779","DOI":"10.1038\/s41598-025-85274-x","article-title":"Preliminary study on the explosive performance of coal dust and prospects for engineering applications","volume":"15","author":"Guo","year":"2025","journal-title":"Sci. Rep."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"107454","DOI":"10.1016\/j.sab.2026.107454","article-title":"Calibration Coefficients for semi-quantitative analysis by LIBS in samples containing Calcium","volume":"237","author":"Lazic","year":"2026","journal-title":"Spectrochim. Acta Part B"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/2\/672\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,20]],"date-time":"2026-01-20T11:31:56Z","timestamp":1768908716000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/26\/2\/672"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,20]]},"references-count":44,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,1]]}},"alternative-id":["s26020672"],"URL":"https:\/\/doi.org\/10.3390\/s26020672","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,20]]}}}