{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T07:41:22Z","timestamp":1774510882569,"version":"3.50.1"},"reference-count":37,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T00:00:00Z","timestamp":1774310400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100018542","name":"Natural Science Foundation of Sichuan Province","doi-asserted-by":"crossref","award":["2024NSFSC0252"],"award-info":[{"award-number":["2024NSFSC0252"]}],"id":[{"id":"10.13039\/501100018542","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["52341301"],"award-info":[{"award-number":["52341301"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>Flexible piezoelectric materials demonstrate broad application potential in wearable health monitoring, human\u2013machine interaction, and biosensing. However, the piezoelectric response of pure PVDF-TrFE is limited and insufficient to meet the requirements for highly sensitive sensing. In this study, ZnO\/PVDF-TrFE composite films with varying ZnO doping contents (3\u201311 wt%) were fabricated and systematically characterized in terms of their structural, thermal, and electrical properties. The results indicate that ZnO significantly promotes the formation of the polar \u03b2-phase in PVDF-TrFE, with the maximum \u03b2-phase content (F\u03b2 = 24.76%) and optimal piezoelectric performance achieved at 9 wt% ZnO doping. Devices based on this optimal composition exhibited stable ultrasonic transmission and reception capabilities under high-frequency pulse excitation, enabling sensitive detection of minor static pressure variations (e.g., contact pressure) through changes in ultrasonic echo signals, thereby realizing wearable conformity monitoring. Moreover, a sensor designed with a three-channel flexible substrate successfully captured human wrist pulse signals with high accuracy, demonstrating the practical utility and reliability of the device in flexible bio-electronic sensing applications.<\/jats:p>","DOI":"10.3390\/bios16040187","type":"journal-article","created":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T09:11:14Z","timestamp":1774429874000},"page":"187","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Enhancement of Piezoelectric Performance in PVDF via ZnO Doping and Its Application in Wearable Real-Time Monitoring of Human Radial Pulse"],"prefix":"10.3390","volume":"16","author":[{"given":"Hao","family":"Zhu","sequence":"first","affiliation":[{"name":"School of Integrated Circuit Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiang","family":"Guo","sequence":"additional","affiliation":[{"name":"Mianyang Municipal Health Commission, Mianyang 621000, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qiang","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-2612-6747","authenticated-orcid":false,"given":"Qian","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Integrated Circuit Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1007\/s11998-022-00690-2","article-title":"Flexible piezoelectric coatings on textiles for energy harvesting and autonomous sensing applications: A review","volume":"20","author":"Rashid","year":"2023","journal-title":"J. Coat. Technol. Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"26","DOI":"10.1038\/s41528-023-00261-4","article-title":"Wearable sensors for telehealth based on emerging materials and nanoarchitectonics","volume":"7","author":"Vaghasiya","year":"2023","journal-title":"npj Flex. Electron."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Zhang, J., Wang, J., Zhong, C., Zhang, Y., Qiu, Y., and Qin, L. (2024). Flexible electronics: Advancements and applications of flexible piezoelectric composites in modern sensing technologies. Micromachines, 15.","DOI":"10.3390\/mi15080982"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"9047","DOI":"10.1109\/JSEN.2019.2925638","article-title":"Energy harvesting for wearable devices: A review","volume":"19","author":"Chong","year":"2019","journal-title":"IEEE Sens. J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2306655","DOI":"10.1002\/smll.202306655","article-title":"Flexible pressure sensors in human\u2013machine interface applications","volume":"20","author":"Xu","year":"2024","journal-title":"Small"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"41806","DOI":"10.1021\/acsami.3c06215","article-title":"Enhanced piezoelectricity of PVDF-TrFE nanofibers by intercalating with electrosprayed BaTiO3","volume":"15","author":"Mirjalali","year":"2023","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Liu, M., Liu, Y., and Zhou, L. (2021). Novel flexible PVDF-TrFE and PVDF-TrFE\/ZnO pressure sensor: Fabrication, characterization and investigation. Micromachines, 12.","DOI":"10.3390\/mi12060602"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"9818","DOI":"10.1021\/acsami.4c19733","article-title":"Anisotropic Poly (vinylidene fluoride-co-trifluoroethylene)\/MXene Aerogel-Based Piezoelectric Nanogenerator for Efficient Kinetic Energy Harvesting and Self-Powered Force Sensing Applications","volume":"17","author":"Suresh","year":"2025","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Ahmed, A., Khoso, N.A., Arain, M.F., Khan, I.A., Javed, K., Khan, A., Memon, S.I., Fan, Q., and Shao, J. (2024). Development of highly flexible piezoelectric PVDF-TRFE\/reduced graphene oxide doped electrospun nano-fibers for self-powered pressure sensor. Polymers, 16.","DOI":"10.3390\/polym16131781"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Al-Harthi, M.A., and Hussain, M. (2022). Effect of the Surface Functionalization of graphene and MWCNT on the thermodynamic, mechanical and electrical properties of the graphene\/MWCNT-PVDF nanocomposites. Polymers, 14.","DOI":"10.3390\/polym14152976"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Stoyanova, S., Ivanov, E., Hegde, L.R., Georgopoulou, A., Clemens, F., Bedoui, F., and Kotsilkova, R. (2024). PVDF Hybrid Nanocomposites with Graphene and Carbon Nanotubes and Their Thermoresistive and Joule Heating Properties. Nanomaterials, 14.","DOI":"10.3390\/nano14110901"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Cerrada, M.L., Arranz-Andr\u00e9s, J., Caballero-Gonz\u00e1lez, A., Bl\u00e1zquez-Bl\u00e1zquez, E., and P\u00e9rez, E. (2023). The \u03b2 form in PVDF nanocomposites with carbon nanotubes: Structural features and properties. Polymers, 15.","DOI":"10.3390\/polym15061491"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"115932","DOI":"10.1088\/1402-4896\/acff4d","article-title":"Toward improved PVDF-BaTiO3 composite dielectrics: Mechanical activation of the filler versus filler content","volume":"98","author":"Vlahovic","year":"2023","journal-title":"Phys. Scr."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"138391","DOI":"10.1016\/j.cej.2022.138391","article-title":"PVDF-based matrix with covalent bonded BaTiO3 nanowires enabled ultrahigh energy density and dielectric properties","volume":"451","author":"Hu","year":"2023","journal-title":"Chem. Eng. J."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"10577","DOI":"10.1039\/D2NJ01425D","article-title":"Enhanced dielectric properties of PVDF-based composite film with BaTiO3@SrTiO3 nanoparticles","volume":"46","author":"Zhao","year":"2022","journal-title":"New J. Chem."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Duraccio, D., Capra, P.P., Fioravanti, A., and Malucelli, G. (2023). Influence of Mechanical Properties on the Piezoelectric Response of UV-Cured Composite Films Containing Different ZnO Morphologies. Polymers, 15.","DOI":"10.3390\/polym15051159"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e00239","DOI":"10.1002\/mame.202500239","article-title":"Progress in Zinc Oxide-Based Polymer Nanocomposites for Advancing Piezoelectric Energy Harvesting and Self-Powered Devices","volume":"310","author":"John","year":"2025","journal-title":"Macromol. Mater. Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"7671","DOI":"10.1039\/D4MA00283K","article-title":"Toward high quality tactile sensors using ZnO\/P(VDF-TrFE) flexible piezoelectric composite films","volume":"5","author":"Taleb","year":"2024","journal-title":"Mater. Adv."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1007\/s10965-022-02890-1","article-title":"P(VDF-TrFE)\/ZnO nanofiber composite based piezoelectric nanogenerator as self-powered sensor: Fabrication and characterization","volume":"29","author":"Kumar","year":"2022","journal-title":"J. Polym. Res."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Han, J., Li, D., Zhao, C., Wang, X., Li, J., and Wu, X. (2019). Highly Sensitive Impact Sensor Based on PVDF-TrFE\/Nano-ZnO Composite Thin Film. Sensors, 19.","DOI":"10.3390\/s19040830"},{"key":"ref_21","first-page":"106033","article-title":"Optimal ZnO doping in PVDF-TrFE for ultrasonic sensing applications","volume":"86","author":"Park","year":"2022","journal-title":"Ultrason. Sonochem."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"11775","DOI":"10.1039\/D3RA08713A","article-title":"PVDF\/ZnO piezoelectric nanofibers designed for monitoring of internal micro-pressure","volume":"14","author":"Chang","year":"2024","journal-title":"RSC Adv."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Xie, L., Wang, G., Jiang, C., Yu, F., and Zhao, X. (2021). Properties and applications of flexible poly (vinylidene fluoride)-based piezoelectric materials. Crystals, 11.","DOI":"10.3390\/cryst11060644"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"4859","DOI":"10.1007\/s00289-022-04275-2","article-title":"P(VDF-TrFE)\/ZnO nanocomposite synthesized by electrospinning: Effect of ZnO nanofiller on physical, mechanical, thermal, rheological and piezoelectric properties","volume":"80","author":"Kumar","year":"2023","journal-title":"Polym. Bull."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"14347","DOI":"10.1039\/D4DT01761G","article-title":"Fabrication of rare earth-doped ZnO-PVDF flexible nanocomposite films for ferroelectric response and their application in piezo-responsive bending sensors","volume":"53","author":"Dutta","year":"2024","journal-title":"Dalt. Trans."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3272","DOI":"10.1002\/app.23137","article-title":"Determination of the \u03b1, \u03b2, and \u03b3 crystalline phases of poly (vinylidene fluoride) films prepared at different conditions","volume":"100","author":"Gregorio","year":"2006","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"91","DOI":"10.1002\/polb.10613","article-title":"Phase transformation to \u03b2-poly (vinylidene fluoride) by milling","volume":"42","author":"Esterly","year":"2004","journal-title":"J. Polym. Sci. Part B Polym. Phys."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.mssp.2019.01.009","article-title":"Band gap tuning and applications of ZnO nanorods in hybrid solar cell: Ag-doped verses Nd-doped ZnO nanorods","volume":"93","author":"Saboor","year":"2019","journal-title":"Mater. Sci. Semicond. Process."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"464","DOI":"10.1016\/j.matdes.2017.01.089","article-title":"Hydrothermal selective growth of low aspect ratio isolated ZnO nanorods","volume":"119","author":"Hassanpour","year":"2017","journal-title":"Mater. Des."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"302","DOI":"10.1016\/j.polymertesting.2016.12.003","article-title":"Crystallization behavior and electroactive properties of PVDF, P(VDF-TrFE) and their blend films","volume":"57","author":"Jia","year":"2017","journal-title":"Polym. Test."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Atif, R., Khaliq, J., Combrinck, M., Hassanin, A.H., Shehata, N., Elnabawy, E., and Shyha, I. (2020). Solution blow spinning of polyvinylidene fluoride based fibers for energy harvesting applications: A review. Polymers, 12.","DOI":"10.3390\/polym12061304"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"4342","DOI":"10.1007\/s10853-015-8986-0","article-title":"Electrospinning-induced preferred dipole orientation in PVDF fibers","volume":"50","author":"Lei","year":"2015","journal-title":"J. Mater. Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"11047","DOI":"10.1039\/c3cc46807k","article-title":"Enhanced frequency response of a highly transparent PVDF\u2013graphene based thin film acoustic actuator","volume":"49","author":"Lee","year":"2013","journal-title":"Chem. Commun."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"5009","DOI":"10.1038\/s41467-023-40763-3","article-title":"Thin, soft, wearable system for continuous wireless monitoring of artery blood pressure","volume":"14","author":"Li","year":"2023","journal-title":"Nat. Commun."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"687","DOI":"10.1038\/s41551-018-0287-x","article-title":"Monitoring of the central blood pressure waveform via a conformal ultrasonic device","volume":"2","author":"Wang","year":"2018","journal-title":"Nat. Biomed. Eng."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"eabi9283","DOI":"10.1126\/sciadv.abi9283","article-title":"Flexible Doppler ultrasound device for the monitoring of blood flow velocity","volume":"7","author":"Wang","year":"2021","journal-title":"Sci. Adv."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1109\/JMEMS.2023.3298021","article-title":"Continuous and non-invasive monitoring of blood pressure based on wearable piezoelectric micromachined ultrasonic transducers array","volume":"32","author":"Zhou","year":"2023","journal-title":"J. Microelectromech. Syst."}],"container-title":["Biosensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/4\/187\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T05:48:53Z","timestamp":1774504133000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-6374\/16\/4\/187"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,24]]},"references-count":37,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["bios16040187"],"URL":"https:\/\/doi.org\/10.3390\/bios16040187","relation":{},"ISSN":["2079-6374"],"issn-type":[{"value":"2079-6374","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,24]]}}}