{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,4]],"date-time":"2026-04-04T18:20:25Z","timestamp":1775326825617,"version":"3.50.1"},"reference-count":34,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,3,5]],"date-time":"2021-03-05T00:00:00Z","timestamp":1614902400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100012166","name":"National Key Research and Development Program of China","doi-asserted-by":"publisher","award":["2019YFB2204903"],"award-info":[{"award-number":["2019YFB2204903"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This communication provides an integrated process route of smelting gallium-based liquid metal (GBLM) in a high vacuum, and injecting GBLM into the antenna channel in high-pressure protective gas, which avoids the oxidation of GBLM during smelting and filling. Then, a frequency-reconfigurable antenna, utilizing the thermal expansion characteristic of GBLM, is proposed. To drive GBLM into an air-proof space, the thermal expansion characteristics of GBLM are required. The dimensions of the radiating element of the liquid metal antenna can be adjusted at different temperatures, resulting in the reconfigurability of the operating frequency. To validate the proposed concept, an L-band antenna prototype was fabricated and measured. Experimental results demonstrate that the GBLM in the antenna was well filled, and the GBLM was not oxidized. Due to the GBLM being in an air-proof channel, the designed liquid metal antenna without electrolytes could be used in an air environment for a long time. The antenna is able to achieve an effective bandwidth of over 1.25\u20132.00 GHz between 25 \u00b0C and 100 \u00b0C. The maximum radiation efficiency and gain in the tunable range are 94% and 2.9 dBi, respectively. The designed antenna also provides a new approach to the fabrication of a temperature sensor that detects temperature in some situations that are challenging for conventional temperature sensing technology.<\/jats:p>","DOI":"10.3390\/s21051793","type":"journal-article","created":{"date-parts":[[2021,3,5]],"date-time":"2021-03-05T00:39:07Z","timestamp":1614904747000},"page":"1793","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":16,"title":["The Design and Manufacturing Process of an Electrolyte-Free Liquid Metal Frequency-Reconfigurable Antenna"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5404-0292","authenticated-orcid":false,"given":"Peng","family":"Qin","sequence":"first","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lei","family":"Wang","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tian-Ying","family":"Liu","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qian-Yu","family":"Wang","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun-Heng","family":"Fu","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guan-Long","family":"Huang","sequence":"additional","affiliation":[{"name":"The College of Electronics and Information Engineering, Shenzhen University, Shenzhen 518060, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8015-0791","authenticated-orcid":false,"given":"Lin","family":"Gui","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jing","family":"Liu","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhong-Shan","family":"Deng","sequence":"additional","affiliation":[{"name":"CAS Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China"},{"name":"School of Future Technology, University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"72","DOI":"10.1109\/LAWP.2013.2238882","article-title":"RF MEMS reconfigurable two-band antenna","volume":"12","author":"Zouhur","year":"2013","journal-title":"IEEE Antennas Wirel. Propag. Lett."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2742","DOI":"10.1109\/TAP.2010.2050455","article-title":"Frequency reconfigurable quasi-yagi folded dipole antenna","volume":"58","author":"Qin","year":"2010","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"515","DOI":"10.1109\/LAWP.2014.2311114","article-title":"A selective frequency-reconfigurable antenna for cognitive radio applications","volume":"13","author":"Mansoul","year":"2014","journal-title":"IEEE Trans. Antennas Propag. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"3151","DOI":"10.1109\/LAWP.2017.2759580","article-title":"A low-cost fluid switch for frequency-reconfigurable Vivaldi antenna","volume":"16","author":"Cristina","year":"2017","journal-title":"IEEE Trans. Antennas Propag. Lett."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Li, J., and Chu, D. (2019). Liquid crystal-based enclosed coplanar waveguide phase shifter for 54\u201366 GHz applications. Crystals, 9.","DOI":"10.3390\/cryst9120650"},{"key":"ref_6","unstructured":"Werndl, E. (1942). Antenna Tunable in Its Length. (2,278,601), U.S. Patent."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Kosta, Y., and Kosta, S. (2008, January 2\u20134). Realization of a microstrip-aperture-coupled-passive-liquid patch antenna. Proceedings of the IEEE International RF and Microwave Conference, Kuala Lumpur, Malaysia.","DOI":"10.1109\/RFM.2008.4897409"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Yee, S., Weinstein, D., Fiering, J., White, D., and Duwel, A. (2015, January 13\u201315). A Miniature Reconfigurable Circularly Polarized Antenna Using Liquid Microswitches. Proceedings of the IEEE 16th Annual Wireless and Microwave Technology Conference, WAMICON, Cocoa Beach, FL, USA.","DOI":"10.1109\/WAMICON.2015.7120370"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2572","DOI":"10.1109\/TAP.2016.2551358","article-title":"Microfluidically reconfigured wideband frequency tunable liquid metal monopole antenna","volume":"64","author":"Dey","year":"2016","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"21823","DOI":"10.1002\/mmce.21823","article-title":"A novel tailored coplanar waveguide circularly polarized antenna controlled by the gravity field","volume":"29","author":"Huang","year":"2019","journal-title":"Int. J. RF Microw. Comput. Aided Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"3632","DOI":"10.1002\/adfm.200900604","article-title":"Reversibly deformable and mechanically tunable fluidic antenna","volume":"19","author":"So","year":"2009","journal-title":"Adv. Funct. Mater."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"874","DOI":"10.1109\/ACCESS.2014.2350531","article-title":"Continuous electrowetting of non-toxic liquid metal for RF applications","volume":"2","author":"Gough","year":"2014","journal-title":"IEEE Access"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"194901","DOI":"10.1063\/1.4919605","article-title":"A reconfigurable liquid metal antenna driven by electrochemically controlled capillarity","volume":"117","author":"Wang","year":"2015","journal-title":"J. Appl. Phys."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1049\/el.2013.2971","article-title":"Two-octave tunable liquid-metal monopole antenna","volume":"50","author":"Morishita","year":"2014","journal-title":"Electron. Lett."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1630","DOI":"10.1049\/el.2015.2782","article-title":"Liquid-metal frequency-reconfigurable slot antenna using air-bubble actuation","volume":"51","author":"Dang","year":"2015","journal-title":"Electron. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1032","DOI":"10.1049\/el.2019.0765","article-title":"Pixelated dual-dipole antenna using electrically actuated liquid metal","volume":"55","author":"Sarabia","year":"2019","journal-title":"Electron. Lett."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"7630","DOI":"10.1109\/TAP.2020.2993110","article-title":"A Frequency- and Polarization- Reconfigurable Slot Antenna Using Liquid Metal","volume":"68","author":"Liu","year":"2020","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"7658","DOI":"10.1109\/TAP.2020.2993310","article-title":"A Radiation Pattern Reconfigurable Fabry P\u00e9rot Antenna Based on Liquid Metal","volume":"68","author":"Yang","year":"2020","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1109\/CJECE.2019.2904898","article-title":"Liquid Metal Reconfigurable Patch Antenna for Linear, RH, and LH Circular Polarization with Frequency Tuning","volume":"43","author":"Arbelaez","year":"2020","journal-title":"Can. J. Electr. Comput. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2360","DOI":"10.1109\/LAWP.2019.2932048","article-title":"Package-in-Dielectric Liquid Patch Antenna Based on Liquid Metal Alloy","volume":"18","author":"Huang","year":"2019","journal-title":"IEEE Antennas Wirel. Propag. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1109\/LAWP.2016.2556983","article-title":"A compound frequency- and polarization- reconfigurable crossed dipole using multidirectional spreading of liquid metal","volume":"16","author":"Wang","year":"2016","journal-title":"IEEE Antennas Wirel. Propag. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Zhou, Y., Fang, S., Liu, H., Wang, Z., and Shao, T. (2020). A function reconfigurable antenna based on liquid metal. Electronics, 9.","DOI":"10.3390\/electronics9050873"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"4406","DOI":"10.1109\/TAP.2011.2165501","article-title":"A reconfigurable patch antenna using liquid metal embedded in a silicone substrate","volume":"59","author":"Mazlouman","year":"2011","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1097","DOI":"10.1002\/adfm.200701216","article-title":"Eutectic aallium-indium (EGaIn): A liquid metal alloy for the formation of stable structures in microchannels at room temperature","volume":"18","author":"Dickey","year":"2008","journal-title":"Adv. Funct. Mater."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Liu, T., Sen, P., and Kim, C.J. (2010, January 24\u201328). Characterization of liquid-metal galinstan for droplet applications. Proceedings of the 2010 IEEE 23rd International Conference on Micro Electromechanical Systems (MEMS), Wanchai, Hong Kong, China.","DOI":"10.1109\/MEMSYS.2010.5442440"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"043508","DOI":"10.1063\/1.4862186","article-title":"Chemical bonding, optical constants, and electrical resistivity of sputter-deposited gallium oxide thin films","volume":"115","author":"Ramana","year":"2014","journal-title":"J. Appl. Phys."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1049\/el.2019.3925","article-title":"Investigation of biasing conditions and energy dissipation in electrochemically controlled capillarity liquid metal electronics","volume":"56","author":"Wang","year":"2020","journal-title":"Electron. Lett."},{"key":"ref_28","first-page":"100050","article-title":"Structural composite laminate materials with low dielectric loss: Theoretical model towards dielectric characterization","volume":"3","author":"Sergolle","year":"2020","journal-title":"Compos. Part C-Open AC"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1804197","DOI":"10.1002\/adfm.201804197","article-title":"Liquid metal droplets wrapped with polysaccharide microgel as bio-compatible aqueous ink for flexible conductive devices","volume":"28","author":"Li","year":"2018","journal-title":"Adv. Funct. Mater."},{"key":"ref_30","unstructured":"Lide, D.R. (2005). CRC Handbook of Chemistry and Physics, CRC Press."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/0022-3093(82)90241-1","article-title":"Glasses from melts and glasses from gels, a comparison","volume":"48","author":"Mackenzie","year":"1982","journal-title":"J. Non-Cryst. Solids"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"54308","DOI":"10.1063\/1.3082518","article-title":"The stabilities of gallium nanowires with different phases encapsulated in a carbon nanotube","volume":"105","author":"Li","year":"2009","journal-title":"J. Appl. Phys."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"8684","DOI":"10.1016\/j.ceramint.2019.01.190","article-title":"Properties of inorganic high-temperature adhesive for high-temperature furnace connection","volume":"45","author":"Chen","year":"2019","journal-title":"Ceram. Int."},{"key":"ref_34","unstructured":"Zhou, X., and Guo, Y. (2014). High Temperature Resistant Unsteady Welding Type Radio Frequency Coaxial-Cable Connector. (CN203967313U), Chinese Patent."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/5\/1793\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:33:09Z","timestamp":1760160789000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/21\/5\/1793"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,3,5]]},"references-count":34,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2021,3]]}},"alternative-id":["s21051793"],"URL":"https:\/\/doi.org\/10.3390\/s21051793","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,3,5]]}}}