{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T04:10:26Z","timestamp":1776399026457,"version":"3.51.2"},"reference-count":32,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2022,1,14]],"date-time":"2022-01-14T00:00:00Z","timestamp":1642118400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2019R1A2C2086747"],"award-info":[{"award-number":["2019R1A2C2086747"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Research on stretchable strain sensors is actively conducted due to increasing interest in wearable devices. However, typical studies have focused on improving the elasticity of the electrode. Therefore, methods of directly connecting wire or attaching conductive tape to materials to detect deformation have been used to evaluate the performance of strain sensors. Polyaniline (PANI), a p-type semiconductive polymer, has been widely used for stretchable electrodes. However, conventional procedures have limitations in determining an appropriate metal for ohmic contact with PANI. Materials that are generally used for connection with PANI form an undesirable metal-semiconductor junction and have significant contact resistance. Hence, they degrade sensor performance. This study secured ohmic contact by adapting Au thin film as the metal contact layer (the MCL), with lower contact resistance and a larger work function than PANI. Additionally, we presented a buffer layer using hard polydimethylsiloxane (PDMS) and structured it into a dumbbell shape to protect the metal from deformation. As a result, we enhanced steadiness and repeatability up to 50% strain by comparing the gauge factors and the relative resistance changes. Consequently, adapting structural methods (the MCL and the dumbbell shape) to a device can result in strain sensors with promising stability, as well as high stretchability.<\/jats:p>","DOI":"10.3390\/s22020630","type":"journal-article","created":{"date-parts":[[2022,1,16]],"date-time":"2022-01-16T20:45:21Z","timestamp":1642365921000},"page":"630","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Improvement in Strain Sensor Stability by Adapting the Metal Contact Layer"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9837-0912","authenticated-orcid":false,"given":"Ji-Yeon","family":"Choy","sequence":"first","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1925-9763","authenticated-orcid":false,"given":"Eun-Bee","family":"Jo","sequence":"additional","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chang-Joo","family":"Yim","sequence":"additional","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2155-5999","authenticated-orcid":false,"given":"Hae-Kyung","family":"Youi","sequence":"additional","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2778-1893","authenticated-orcid":false,"given":"Jung-Hoon","family":"Hwang","sequence":"additional","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jun-Ho","family":"Lee","sequence":"additional","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1127-5766","authenticated-orcid":false,"given":"Hyun-Seok","family":"Kim","sequence":"additional","affiliation":[{"name":"Division of Electronics and Electrical Engineering, Dongguk University, Seoul 04620, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"3530","DOI":"10.1038\/s41467-020-17301-6","article-title":"A high performance wearable strain sensor with advanced thermal management for motion monitoring","volume":"11","author":"Tan","year":"2020","journal-title":"Nat. Commun."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5154","DOI":"10.1021\/nn501204t","article-title":"Highly stretchable and sensitive strain sensor based on silver nanowire\u2013elastomer nanocomposite","volume":"8","author":"Amjadi","year":"2014","journal-title":"ACS Nano"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2102488","DOI":"10.1002\/adma.202102488","article-title":"Stretchable and Highly Permeable Nanofibrous Sensors for Detecting Complex Human Body Motion","volume":"33","author":"Horev","year":"2021","journal-title":"Adv. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2944","DOI":"10.1039\/C5NR08618C","article-title":"Patterned, highly stretchable and conductive nanofibrous PANI\/PVDF strain sensors based on electrospinning and in situ polymerization","volume":"8","author":"Yu","year":"2016","journal-title":"Nanoscale"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"107938","DOI":"10.1016\/j.compscitech.2019.107938","article-title":"A stretchable and transparent strain sensor based on sandwich-like PDMS\/CNTs\/PDMS composite containing an ultrathin conductive CNT layer","volume":"186","author":"Chen","year":"2020","journal-title":"Compos. Sci. Technol."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4304","DOI":"10.1039\/C6TC00300A","article-title":"A highly stretchable strain sensor based on a graphene\/silver nanoparticle synergic conductive network and a sandwich structure","volume":"4","author":"Chen","year":"2016","journal-title":"J. Mater. Chem. C"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/j.orgel.2017.05.001","article-title":"Flexible strain sensor with high performance based on PANI\/PDMS films","volume":"47","author":"Gong","year":"2017","journal-title":"Org. Electron."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"498","DOI":"10.3390\/nano3030498","article-title":"Conducting polyaniline nanowire and its applications in chemiresistive sensing","volume":"3","author":"Song","year":"2013","journal-title":"Nanomaterials"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e437","DOI":"10.1038\/am.2017.181","article-title":"A semitransparent snake-like tactile and olfactory bionic sensor with reversibly stretchable properties","volume":"9","author":"Cai","year":"2017","journal-title":"NPG Asia Mater."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1678","DOI":"10.1002\/adfm.201504755","article-title":"Stretchable, skin-mountable, and wearable strain sensors and their potential applications: A review","volume":"26","author":"Amjadi","year":"2016","journal-title":"Adv. Funct. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"13241","DOI":"10.1038\/s41598-018-31628-7","article-title":"Stretchable and washable strain sensor based on cracking structure for human motion monitoring","volume":"8","author":"Tolvanen","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1039\/C4RA11832D","article-title":"Tuning the work function of polyaniline via camphorsulfonic acid: An X-ray photoelectron spectroscopy investigation","volume":"5","author":"Abdulrazzaq","year":"2015","journal-title":"RSC Adv."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Hajibadali, A., Nejhad, M.B., Farzi, G., and Rad, H.H. (2013, January 14\u201316). Fabrication and characterization of polyaniline based Schottky diode. Proceedings of the 2013 21st Iranian Conference on Electrical Engineering (ICEE), Mashhad, Iran.","DOI":"10.1109\/IranianCEE.2013.6599532"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"146786","DOI":"10.1016\/j.apsusc.2020.146786","article-title":"Zinc oxide nanorods assisted by polyaniline network as a flexible self-powered Ultraviolet photodetector: A comprehensive study","volume":"527","author":"Ghorbani","year":"2020","journal-title":"Appl. Surf. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"11092","DOI":"10.1039\/C7TC03434B","article-title":"Engineering of carbon nanotube\/polydimethylsiloxane nanocomposites with enhanced sensitivity for wearable motion sensor","volume":"5","author":"Li","year":"2017","journal-title":"J. Mater. Chem. C"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Huang, L., Wang, H., Wu, P., Haung, W., Gau, W., Fang, F., Cai, N., Chen, R., and Zhu, Z. (2020). Wearable flexible strain sensor based on three-dimensional wavy laser-induced graphene and silicone rubber. Sensors, 20.","DOI":"10.3390\/s20154266"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"276","DOI":"10.1016\/j.compscitech.2018.01.019","article-title":"A highly stretchable and stable train sensor based on hybrid carbon nanofillers\/polydimethylsiloxane conductive composites for large human motions monitoring","volume":"156","author":"Zheng","year":"2018","journal-title":"Compos. Sci. Technol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"281","DOI":"10.1007\/s10544-005-6070-2","article-title":"Characterization of polydimethylsiloxane (PDMS) properties for biomedical micro\/nanosystems","volume":"7","author":"Mata","year":"2005","journal-title":"Biomed. Microdevices"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"035017","DOI":"10.1088\/0960-1317\/24\/3\/035017","article-title":"Mechanical characterization of bulk Sylgard 184 for microfluidics and microengineering","volume":"24","author":"Johnston","year":"2014","journal-title":"J. Micromech. Microeng."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Jin, C., Ma, C., Yang, Z., and Lin, H. (2020). A force measurement method based on flexible PDMS grating. Appl. Sci., 10.","DOI":"10.3390\/app10072296"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1039\/C1LC20721K","article-title":"Photolithographic surface micromachining of polydimethylsiloxane (PDMS)","volume":"12","author":"Chen","year":"2012","journal-title":"Lab Chip"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2847","DOI":"10.1002\/smll.201001456","article-title":"An Effective Lift-Off Method for Patterning High-Density Gold Interconnects on an Elastomeric Substrate","volume":"6","author":"Guo","year":"2010","journal-title":"Small"},{"key":"ref_23","unstructured":"Van Dam, R.M. (2006). Solvent-Resistant Elastomeric Microfluidic Devices and Applications, California Institute of Technology."},{"key":"ref_24","unstructured":"(2009). Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomer (Standard No. ASTM D412-16)."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.polymer.2016.01.070","article-title":"Green silicone elastomer obtained from a counterintuitively stable mixture of glycerol and PDMS","volume":"86","author":"Mazurek","year":"2016","journal-title":"Polymer"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Jeronimo, K., Koutsos, V., Cheung, R., and Mastropaolo, E. (2021). PDMS-ZnO Piezoelectric Nanocomposites for pressure sensors. Sensors, 17.","DOI":"10.3390\/s21175873"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"9066","DOI":"10.1039\/c2ra20880f","article-title":"Versatile method for bonding hard and soft materials","volume":"2","author":"Sunkara","year":"2012","journal-title":"RSC Adv."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1039\/C5MH00290G","article-title":"Multi-functional silicone stamps for reactive release agent transfer in UV roll-to-roll nanoimprinting","volume":"3","author":"Dumond","year":"2016","journal-title":"Mater. Horiz."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3042","DOI":"10.1021\/ma982034l","article-title":"Siloxane polymers for high-resolution, high-accuracy soft lithography","volume":"33","author":"Schmid","year":"2000","journal-title":"Macromolecules"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"054114","DOI":"10.1063\/1.4964717","article-title":"Surface micromachining of polydimethylsiloxane for microfluidics applications","volume":"10","author":"Hill","year":"2016","journal-title":"Biomicrofluidics"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"152105","DOI":"10.1109\/ACCESS.2020.3017218","article-title":"A flexible patch-type strain sensor based on polyaniline for continuous monitoring of pulse wave","volume":"8","author":"Kang","year":"2020","journal-title":"IEEE Access"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1186\/s11671-018-2499-0","article-title":"Electrically conductive TPU nanofibrous composite with high stretchable for flexible strain sensor","volume":"13","author":"Tong","year":"2018","journal-title":"Nanoscale Res. Lett."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/2\/630\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,13]],"date-time":"2025-10-13T13:27:21Z","timestamp":1760362041000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/22\/2\/630"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,1,14]]},"references-count":32,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2022,1]]}},"alternative-id":["s22020630"],"URL":"https:\/\/doi.org\/10.3390\/s22020630","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,1,14]]}}}