{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,18]],"date-time":"2026-06-18T08:09:16Z","timestamp":1781770156816,"version":"3.54.5"},"reference-count":32,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2020,5,14]],"date-time":"2020-05-14T00:00:00Z","timestamp":1589414400000},"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>We developed and investigated a particular geometry of transducers, emulating the shape of bats\u2019 cochlea, to transmit and receive ultrasounds in the air. Their design involved the use of polyvinylidene fluoride (PVDF) as a piezoelectric material, thanks to its excellent conformability and flexibility. This material offers the primary requirements for sensing devices in applications such as sonar system or energy harvesting technology. The piezo film was folded according to both the Archimedean and Fibonacci spirals, and their performances were investigated in the frequency range from 20 kHz up to more than 80 kHz. The finite element analysis (FEA) of the proposed transducers highlighted the presence of multiple resonance vibrations, proved by the experimental measurements of the equivalent electric impedance and frequency response. Far-field radiation patterns demonstrated, horizontally and vertically, omnidirectional properties both as transmitters and receivers. All was enough to establish the best validity of the spiral shaped transducers for applications based on the bio sonar principle.<\/jats:p>","DOI":"10.3390\/s20102800","type":"journal-article","created":{"date-parts":[[2020,5,14]],"date-time":"2020-05-14T10:27:19Z","timestamp":1589452039000},"page":"2800","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Ultrasonic Transducers Shaped in Archimedean and Fibonacci Spiral: A Comparison"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6163-7804","authenticated-orcid":false,"given":"Antonino S.","family":"Fiorillo","sequence":"first","affiliation":[{"name":"BATS Lab, Department of Health Sciences, University \u201cMagna Graecia\u201d of Catanzaro, 88100 Catanzaro, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3391-1698","authenticated-orcid":false,"given":"Salvatore Andrea","family":"Pullano","sequence":"additional","affiliation":[{"name":"BATS Lab, Department of Health Sciences, University \u201cMagna Graecia\u201d of Catanzaro, 88100 Catanzaro, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2705-8718","authenticated-orcid":false,"given":"Maria Giovanna","family":"Bianco","sequence":"additional","affiliation":[{"name":"BATS Lab, Department of Health Sciences, University \u201cMagna Graecia\u201d of Catanzaro, 88100 Catanzaro, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6392-5383","authenticated-orcid":false,"given":"Costantino Davide","family":"Critello","sequence":"additional","affiliation":[{"name":"BATS Lab, Department of Health Sciences, University \u201cMagna Graecia\u201d of Catanzaro, 88100 Catanzaro, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,5,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1108\/IR-01-2015-0010","article-title":"Underwater robots: A review of technologies and applications","volume":"42","author":"Bogue","year":"2015","journal-title":"Ind. Robot. Int. J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1177\/027836499501400401","article-title":"Mobile Robot Sonar for Target Localization and Classification","volume":"14","author":"Kleeman","year":"1995","journal-title":"Int. J. Robot. Res."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Pullano, S.A., Fiorillo, A.S., La Gatta, A., Lamonaca, F., and Carni, D. (2016, January 15\u201318). Comprehensive system for the evaluation of the attention level of a driver. Proceedings of the 2016 IEEE International Symposium on Medical Measurements and Applications (MeMeA), Benevento, Italy.","DOI":"10.1109\/MeMeA.2016.7533710"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1007\/BF02066251","article-title":"Lazzaro spallanzani: A blow against spontaneous generation","volume":"9","author":"Ariatti","year":"1993","journal-title":"Aerobiologia"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"454","DOI":"10.2307\/1374231","article-title":"Experimental Determination of Supersonic Notes Emitted by Bats","volume":"19","author":"Pierce","year":"1938","journal-title":"J. Mammal."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"975","DOI":"10.1143\/JJAP.8.975","article-title":"The Piezoelectricity of Poly (vinylidene Fluoride)","volume":"8","author":"Kawai","year":"1969","journal-title":"Jpn. J. Appl. Phys."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Elahi, H., Eugeni, M., and Gaudenzi, P. (2018). A Review on Mechanisms for Piezoelectric-Based Energy Harvesters. Energies, 11.","DOI":"10.3390\/en11071850"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"688","DOI":"10.1109\/58.165552","article-title":"Design and characterization of a PVDF ultrasonic range sensor","volume":"39","author":"Fiorillo","year":"1992","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1375","DOI":"10.1109\/58.808860","article-title":"Curved PVDF airborne transducer","volume":"46","author":"Wang","year":"1999","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1109\/TUFFC.2002.1002461","article-title":"Cylindrical PVDF film transmitters and receivers for air ultrasound","volume":"49","author":"Toda","year":"2002","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"536","DOI":"10.1109\/TMC.2006.57","article-title":"Broadband ultrasonic location systems for improved indoor positioning","volume":"5","author":"Hazas","year":"2006","journal-title":"IEEE Trans. Mob. Comput."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Fiorillo, A.S., Pullano, S.A., Critello, C.D., Citraro, R., De Sarro, G., and Russo, E. (2013, January 4\u20135). Measurements of rat brain activity originating from ultrasound waves in air. Proceedings of the 2013 IEEE International Symposium on Medical Measurements and Applications (MeMeA), Gatineau, Canada.","DOI":"10.1109\/MeMeA.2013.6549742"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1063\/1.116447","article-title":"Ultrasound transducer with low synthetic quality factor","volume":"68","author":"Fiorillo","year":"1996","journal-title":"Appl. Phys. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"983","DOI":"10.1109\/JSEN.2015.2490260","article-title":"Simulation and Measurement of Air-Coupled Semi-Circular and Conical PVDF Sensors","volume":"16","author":"Gurkan","year":"2015","journal-title":"IEEE Sensors J."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8618","DOI":"10.1109\/JSEN.2019.2922552","article-title":"Truncated Conical PVDF Film Transducer for Air Ultrasound","volume":"19","author":"Chen","year":"2019","journal-title":"IEEE Sensors J."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1109\/JSEN.2019.2941980","article-title":"Quasi-Spherical PVDF Ultrasonic Transducer with Double-Cylindrical PVDF Structure","volume":"20","author":"Chen","year":"2020","journal-title":"IEEE Sensors J."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1016\/j.sna.2019.05.019","article-title":"Bioinspired US sensor for broadband applications","volume":"294","author":"Fiorillo","year":"2019","journal-title":"Sens. Actuators, A."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"635","DOI":"10.1109\/TUFFC.2019.2948817","article-title":"Spiral-Shaped Biologically-Inspired Ultrasonic Sensor","volume":"67","author":"Fiorillo","year":"2020","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"17566","DOI":"10.1038\/s41598-017-16126-6","article-title":"Variations in cochlear duct shape revealed on clinical CT images with an automatic tracing method","volume":"7","author":"Kalkman","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"7500","DOI":"10.1038\/s41598-017-07795-4","article-title":"Spiral Form of the Human Cochlea Results from Spatial Constraints","volume":"7","author":"Pietsch","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1038\/scientificamerican0690-60","article-title":"Bisonar and neural computation in bats","volume":"262","author":"Suga","year":"1990","journal-title":"Sci. Am."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1007\/BF01351362","article-title":"The cochlear frequency map of the mustache bat, Pteronotus parnellii","volume":"157","author":"Vater","year":"1985","journal-title":"J. Comp. Physiol. A"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"K\u00f6ssl, M., Vater, M., and Fay, R.R. (1995). Cochlear Structure and Function in Bats, Springer Science and Business Media LLC.","DOI":"10.1007\/978-1-4612-2556-0_5"},{"key":"ref_24","unstructured":"(2020, March 01). 176-1987-IEEE Standard on Piezoelectricity. Available online: https:\/\/ieeexplore.ieee.org\/document\/26560."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Tsuji, K., and M\u00fcller, S. (2019). Appearance in Nature. In Spirals and Vortices. The Frontiers Collection, Springer Nature Switzerland AG.","DOI":"10.1007\/978-3-030-05798-5"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"11764","DOI":"10.1002\/anie.201704499","article-title":"Fractal MTW Zeolite Crystals: Hidden Dimensions in Nanoporous Materials","volume":"56","author":"Wang","year":"2017","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1109\/TNANO.2012.2193413","article-title":"Deposition of Zeolite Thin Layers Onto Silicon Wafers for Biomedical Use","volume":"11","author":"Fiorillo","year":"2012","journal-title":"IEEE Trans. Nanotechnol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"214","DOI":"10.1109\/TNANO.2014.2378892","article-title":"Absorption of Urea Into Zeolite Layer Integrated With Microelectronic Circuits","volume":"14","author":"Fiorillo","year":"2014","journal-title":"IEEE Trans. Nanotechnol."},{"key":"ref_29","first-page":"9","article-title":"Polymer Piezoelectric Transducers for Ultrasonic NDE","volume":"1","author":"Xue","year":"1996","journal-title":"NDTnet"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1080\/01411598908206863","article-title":"Ferroelectric properties of vinylidene fluoride copolymers","volume":"18","author":"Furukawa","year":"1989","journal-title":"Phase Transitions"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2725","DOI":"10.1109\/JSEN.2014.2315738","article-title":"Pyroelectric Sensor for Temperature Monitoring of Biological Fluids in Microchannel Devices","volume":"14","author":"Pullano","year":"2014","journal-title":"IEEE Sensors J."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1432","DOI":"10.1109\/58.883532","article-title":"Noise analysis in air-coupled PVDF ultrasonic sensors","volume":"47","author":"Fiorillo","year":"2000","journal-title":"IEEE Trans. Ultrason. Ferroelectr. Freq. Control."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/10\/2800\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:28:52Z","timestamp":1760174932000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/10\/2800"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,5,14]]},"references-count":32,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2020,5]]}},"alternative-id":["s20102800"],"URL":"https:\/\/doi.org\/10.3390\/s20102800","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,5,14]]}}}