{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,2]],"date-time":"2026-05-02T09:58:57Z","timestamp":1777715937610,"version":"3.51.4"},"reference-count":51,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2023,9,1]],"date-time":"2023-09-01T00:00:00Z","timestamp":1693526400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institutes of Health","award":["R00-EB024341"],"award-info":[{"award-number":["R00-EB024341"]}]},{"name":"National Institutes of Health","award":["R01-EB031820"],"award-info":[{"award-number":["R01-EB031820"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Flexible and stretchable radiofrequency coils for magnetic resonance imaging represent an emerging and rapidly growing field. The main advantage of such coil designs is their conformal nature, enabling a closer anatomical fit, patient comfort, and freedom of movement. Previously, we demonstrated a proof-of-concept single element stretchable coil design with a self-tuning smart geometry. In this work, we evaluate the feasibility of scaling this coil concept to a multi-element coil array and the associated engineering and manufacturing challenges. To this goal, we study a dual-channel coil array using full-wave simulations, bench testing, in vitro, and in vivo imaging in a 3 T scanner. We use three fabrication techniques to manufacture dual-channel receive coil arrays: (1) single-layer casting, (2) double-layer casting, and (3) direct-ink-writing. All fabricated arrays perform equally well on the bench and produce similar sensitivity maps. The direct-ink-writing method is found to be the most advantageous fabrication technique for fabrication speed, accuracy, repeatability, and total coil array thickness (0.6 mm). Bench tests show excellent frequency stability of 128 \u00b1 0.6 MHz (0% to 30% stretch). Compared to a commercial knee coil array, the stretchable coil array is more conformal to anatomy and provides 50% improved signal-to-noise ratio in the region of interest.<\/jats:p>","DOI":"10.3390\/s23177588","type":"journal-article","created":{"date-parts":[[2023,9,1]],"date-time":"2023-09-01T09:12:22Z","timestamp":1693559542000},"page":"7588","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Dual-Channel Stretchable, Self-Tuning, Liquid Metal Coils and Their Fabrication Techniques"],"prefix":"10.3390","volume":"23","author":[{"given":"Elizaveta","family":"Motovilova","sequence":"first","affiliation":[{"name":"Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA"},{"name":"Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5747-2020","authenticated-orcid":false,"given":"Terry","family":"Ching","sequence":"additional","affiliation":[{"name":"Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore"},{"name":"Digital Manufacturing and Design (DManD) Centre, Singapore University of Technology and Design, Singapore 487372, Singapore"},{"name":"Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2707-6000","authenticated-orcid":false,"given":"Jana","family":"Vincent","sequence":"additional","affiliation":[{"name":"GE Healthcare, Aurora, OH 44202, USA"}]},{"given":"James","family":"Shin","sequence":"additional","affiliation":[{"name":"Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2847-9378","authenticated-orcid":false,"given":"Ek Tsoon","family":"Tan","sequence":"additional","affiliation":[{"name":"Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA"}]},{"given":"Victor","family":"Taracila","sequence":"additional","affiliation":[{"name":"GE Healthcare, Aurora, OH 44202, USA"}]},{"given":"Fraser","family":"Robb","sequence":"additional","affiliation":[{"name":"GE Healthcare, Aurora, OH 44202, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9684-2354","authenticated-orcid":false,"given":"Michinao","family":"Hashimoto","sequence":"additional","affiliation":[{"name":"Pillar of Engineering Product Development, Singapore University of Technology and Design, Singapore 487372, Singapore"},{"name":"Digital Manufacturing and Design (DManD) Centre, Singapore University of Technology and Design, Singapore 487372, Singapore"}]},{"given":"Darryl B.","family":"Sneag","sequence":"additional","affiliation":[{"name":"Department of Radiology and Imaging, Hospital for Special Surgery, New York, NY 10021, USA"}]},{"given":"Simone Angela","family":"Winkler","sequence":"additional","affiliation":[{"name":"Department of Radiology, Weill Cornell Medicine, New York, NY 10065, USA"}]}],"member":"1968","published-online":{"date-parts":[[2023,9,1]]},"reference":[{"key":"ref_1","unstructured":"Vaughan, J.T., and Griffiths, J.R. (2012). RF Coils for MRI, John Wiley & Sons."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1201","DOI":"10.1002\/mrm.21948","article-title":"Noise figure limits for circular loop MR coils","volume":"61","author":"Kumar","year":"2009","journal-title":"Magn. Reson. Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"590","DOI":"10.1002\/jmri.26187","article-title":"RF coils: A practical guide for nonphysicists","volume":"48","author":"Gruber","year":"2018","journal-title":"J. Magn. Reson. Imaging"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1026","DOI":"10.1002\/jmri.27865","article-title":"Recent Advances in Radio-Frequency Coil Technologies: Flexible, Wireless, and Integrated Coil Arrays","volume":"55","author":"Darnell","year":"2022","journal-title":"J. Magn. Reson. Imaging"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"482","DOI":"10.1109\/TMI.2009.2036996","article-title":"An MRI receiver coil produced by inkjet printing directly on to a flexible substrate","volume":"29","author":"Mager","year":"2010","journal-title":"IEEE Trans. Med. Imaging"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"10839","DOI":"10.1038\/ncomms10839","article-title":"Screen-printed flexible MRI receive coils","volume":"7","author":"Corea","year":"2016","journal-title":"Nat. Commun."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1002\/mrm.26399","article-title":"Materials and methods for higher performance screen-printed flexible MRI receive coils","volume":"78","author":"Corea","year":"2017","journal-title":"Magn. Reson. Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1148\/radiol.2019181883","article-title":"Evaluation of a flexible 12-channel screen-printed pediatric MRI coil","volume":"291","author":"Winkler","year":"2019","journal-title":"Radiology"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1332","DOI":"10.1002\/mrm.24121","article-title":"Flexible transceiver array for ultrahigh field human MR imaging","volume":"68","author":"Wu","year":"2012","journal-title":"Magn. Reson. Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1015","DOI":"10.1002\/mrm.25999","article-title":"A semiflexible 64-channel receive-only phased array for pediatric body MRI at 3T","volume":"76","author":"Zhang","year":"2016","journal-title":"Magn. Reson. Med."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"47","DOI":"10.1016\/j.jmr.2018.08.013","article-title":"A flexible 12-channel transceiver array of transmission line resonators for 7 T MRI","volume":"296","author":"Hosseinnezhadian","year":"2018","journal-title":"J. Magn. Reson."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3406","DOI":"10.1002\/mrm.27637","article-title":"Size-adaptable \u201cTrellis\u201d structure for tailored MRI coil arrays","volume":"81","author":"Zhang","year":"2019","journal-title":"Magn. Reson. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"15010","DOI":"10.1038\/s41598-022-19282-6","article-title":"A flexible MRI coil based on a cable conductor and applied to knee imaging","volume":"12","author":"Wang","year":"2022","journal-title":"Sci. Rep."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1219","DOI":"10.1002\/jmri.21463","article-title":"128-channel body MRI with a flexible high-density receiver-coil array","volume":"28","author":"Hardy","year":"2008","journal-title":"J. Magn. Reson. Imaging"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"460","DOI":"10.1002\/nbm.3264","article-title":"Knee MRI under varying flexion angles utilizing a flexible flat cable antenna","volume":"28","author":"Jia","year":"2015","journal-title":"NMR Biomed."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"429","DOI":"10.1002\/mrm.21868","article-title":"Mechanically adjustable coil array for wrist MRI","volume":"61","author":"Pruessmann","year":"2009","journal-title":"Magn. Reson. Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"e3944","DOI":"10.1002\/nbm.3944","article-title":"Size-adaptable 13-channel receive array for brain MRI in human neonates at 3 T","volume":"31","author":"Foias","year":"2018","journal-title":"NMR Biomed."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"80","DOI":"10.3389\/fphy.2020.00080","article-title":"Anatomically Adaptive Coils for MRI\u2014A 6-Channel Array for Knee Imaging at 1.5 Tesla","volume":"8","author":"Gruber","year":"2020","journal-title":"Front. Phys."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"590","DOI":"10.1002\/mrm.21488","article-title":"A geometrically adjustable 16-channel transmit\/receive transmission line array for improved RF efficiency and parallel imaging performance at 7 Tesla","volume":"59","author":"Adriany","year":"2008","journal-title":"Magn. Reson. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"570","DOI":"10.1038\/s41551-018-0233-y","article-title":"A high-impedance detector-array glove for magnetic resonance imaging of the hand","volume":"2","author":"Zhang","year":"2018","journal-title":"Nat. Biomed. Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1016\/j.jmr.2016.10.008","article-title":"Multi-turn multi-gap transmission line resonators\u2013Concept, design and first implementation at 4.7 T and 7 T","volume":"273","author":"Laistler","year":"2016","journal-title":"J. Magn. Reson."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1135","DOI":"10.1002\/mrm.27964","article-title":"Shielded-coaxial-cable coils as receive and transceive array elements for 7T human MRI","volume":"83","author":"Ruytenberg","year":"2020","journal-title":"Magn. Reson. Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1267","DOI":"10.1109\/TMI.2021.3051390","article-title":"Flexible multi-turn multi-gap coaxial RF coils: Design concept and implementation for Magnetic Resonance Imaging at 3 and 7 Tesla","volume":"40","author":"Nohava","year":"2021","journal-title":"IEEE Trans. Med. Imaging"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1672","DOI":"10.1002\/mrm.28215","article-title":"A flexible five-channel shielded-coaxial-cable (SCC) transceive neck coil for high-resolution carotid imaging at 7T","volume":"84","author":"Ruytenberg","year":"2020","journal-title":"Magn. Reson. Med."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"552","DOI":"10.2214\/AJR.20.22812","article-title":"Application of adaptive image receive coil technology for whole-brain imaging","volume":"216","author":"Cogswell","year":"2021","journal-title":"AJR. Am. J. Roentgenol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"872","DOI":"10.1002\/mrm.23240","article-title":"Stretchable coil arrays: Application to knee imaging under varying flexion angles","volume":"67","author":"Pruessmann","year":"2012","journal-title":"Magn. Reson. Med."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2187","DOI":"10.1109\/TBME.2019.2956682","article-title":"Conductive thread-based stretchable and flexible radiofrequency coils for magnetic resonance imaging","volume":"67","author":"Vincent","year":"2019","journal-title":"IEEE Trans. Biomed. Eng."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"517","DOI":"10.1109\/LMWC.2021.3068930","article-title":"Wearable and elastic surface coil for 1H magnetic resonance imaging","volume":"31","author":"Yegin","year":"2021","journal-title":"IEEE Microw. Wirel. Compon. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"5115","DOI":"10.1109\/TAP.2019.2891700","article-title":"A novel flexible electrotextile 3T MRI RF coil array for carotid artery imaging: Design, characterization, and prototyping","volume":"67","author":"Zhang","year":"2019","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"107510","DOI":"10.1016\/j.jmr.2023.107510","article-title":"Stretchable receive coil for 7T small animal MRI","volume":"353","author":"Ramesh","year":"2023","journal-title":"J. Magn. Reson."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"8844","DOI":"10.1038\/s41598-020-65634-5","article-title":"Detector clothes for MRI: A wearable array receiver based on liquid metal in elastic tubes","volume":"10","author":"Port","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"16228","DOI":"10.1038\/s41598-021-95335-6","article-title":"Stretchable self-tuning MRI receive coils based on liquid metal technology (LiquiTune)","volume":"11","author":"Motovilova","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1703744","DOI":"10.1002\/adma.201703744","article-title":"Adsorbed eutectic GaIn structures on a neoprene foam for stretchable MRI coils","volume":"29","author":"Varga","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_34","first-page":"246","article-title":"A flexible mercury-filled surface coil for MR imaging","volume":"7","author":"Malko","year":"1986","journal-title":"Am. J. Neuroradiol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"517","DOI":"10.1016\/0730-725X(90)90061-6","article-title":"A new, fully versatile surface coil for MRI","volume":"8","author":"Rousseau","year":"1990","journal-title":"Magn. Reson. Imaging"},{"key":"ref_36","unstructured":"Duan, Q., Lu, H., Cooper, C., Zong, X., Duyn, J.H., Dickey, M.D., and Wang, S. (2016;, January 7\u20138). Liquid metal based deformable transmitter for MR imaging: A feasibility study. Proceedings of the ISMRM 24th Annual Meeting & Exhibition, Singapore."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2882","DOI":"10.1002\/mrm.28662","article-title":"Elastomer coils for wearable MR detection","volume":"85","author":"Port","year":"2021","journal-title":"Magn. Reson. Med."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"2327","DOI":"10.1002\/mrm.28540","article-title":"How thin can you go? Performance of thin copper and aluminum RF coil conductors","volume":"85","author":"Barta","year":"2021","journal-title":"Magn. Reson. Med."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1420","DOI":"10.1109\/TMI.2018.2888959","article-title":"Automatic resonance frequency retuning of stretchable liquid metal receive coil for magnetic resonance imaging","volume":"38","author":"Mehmann","year":"2018","journal-title":"IEEE Trans. Med. Imaging"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1002\/mrm.1910160203","article-title":"The NMR phased array","volume":"16","author":"Roemer","year":"1990","journal-title":"Magn. Reson. Med."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"4775","DOI":"10.1038\/s41467-022-32126-1","article-title":"Integrated 3D printing of flexible electroluminescent devices and soft robots","volume":"13","author":"Zhang","year":"2022","journal-title":"Nat. Commun."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2008062","DOI":"10.1002\/adma.202008062","article-title":"Ultra-Deformable and Tissue-Adhesive Liquid Metal Antennas with High Wireless Powering Efficiency","volume":"33","author":"Yamagishi","year":"2021","journal-title":"Adv. Mater."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1606425","DOI":"10.1002\/adma.201606425","article-title":"Stretchable and Soft Electronics using Liquid Metals","volume":"29","author":"Dickey","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1097","DOI":"10.1002\/adfm.200701216","article-title":"Eutectic gallium-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_45","unstructured":"(2021). Determination of Signal-to-Noise Ratio (SNR) in Diagnostic Magnetic Resonance Imaging (Standard No. NEMA MS 1-2008 (R2014, R2020))."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1002\/cmr.b.21319","article-title":"Dependence of and field patterns of surface coils on the electrical properties of the sample and the MR operating frequency","volume":"46","author":"Vaidya","year":"2016","journal-title":"Concepts Magn. Reson. Part B Magn. Reson. Eng."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"3498","DOI":"10.1002\/mp.16255","article-title":"Silicone-based materials with tailored MR relaxation characteristics for use in reduced coil visibility and in tissue-mimicking phantom design","volume":"50","author":"Motovilova","year":"2023","journal-title":"Med. Phys."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"936","DOI":"10.1002\/mrm.21566","article-title":"Multinuclear NMR investigation of probe construction materials at 9.4 T","volume":"59","author":"Marjanska","year":"2008","journal-title":"Magn. Reson. Med."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1652","DOI":"10.1002\/mrm.22558","article-title":"RF coil considerations for short-T2 MRI","volume":"64","author":"Horch","year":"2010","journal-title":"Magn. Reson. Med."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"802","DOI":"10.1097\/RLI.0b013e318188601f","article-title":"Three-dimensional ultrashort echo time imaging of solid polymers on a 3-Tesla whole-body MRI scanner","volume":"43","author":"Springer","year":"2008","journal-title":"Investig. Radiol."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"914","DOI":"10.1002\/pc.25875","article-title":"Silicone composites cured under a high electric field: An electromechanical experimental study","volume":"42","author":"Kumar","year":"2021","journal-title":"Polym. Compos."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/17\/7588\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:44:47Z","timestamp":1760129087000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/17\/7588"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,9,1]]},"references-count":51,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2023,9]]}},"alternative-id":["s23177588"],"URL":"https:\/\/doi.org\/10.3390\/s23177588","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,9,1]]}}}