{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:38:59Z","timestamp":1760240339718,"version":"build-2065373602"},"reference-count":25,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2019,5,12]],"date-time":"2019-05-12T00:00:00Z","timestamp":1557619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["CBET-1706472, ECCS-1707049"],"award-info":[{"award-number":["CBET-1706472, ECCS-1707049"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>An optical cavity-based sensor using a differential detection method has been proposed for point-of-care diagnostics. We developed a low-cost and portable optical cavity-based sensor system using a 3D printer and off-the-shelf optical components. In this paper, we demonstrate the sensing capability of the portable system through refractive index measurements. Fabricated optical cavity samples were tested using the portable system and compared to simulation results. A referencing technique and digital low pass filtering were applied to reduce the noise of the portable system. The measurement results match the simulation results well and show the improved linearity and sensitivity by employing the differential detection method. The limit of detection achieved was 1.73 \u00d7 10\u22125 Refractive Index Unit (RIU), which is comparable to other methods for refractive index sensing.<\/jats:p>","DOI":"10.3390\/s19092193","type":"journal-article","created":{"date-parts":[[2019,5,13]],"date-time":"2019-05-13T05:35:39Z","timestamp":1557725739000},"page":"2193","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Demonstration of a Low-Cost and Portable Optical Cavity-Based Sensor through Refractive Index Measurements"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2670-5941","authenticated-orcid":false,"given":"Donggee","family":"Rho","sequence":"first","affiliation":[{"name":"Electrical Engineering Department, Baylor University, One Bear Place #97356, Waco, TX 76798, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Caitlyn","family":"Breaux","sequence":"additional","affiliation":[{"name":"Biomedical Engineering Program, Baylor University, One Bear Place #97356, Waco, TX 76798, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Seunghyun","family":"Kim","sequence":"additional","affiliation":[{"name":"Electrical Engineering Department, Baylor University, One Bear Place #97356, Waco, TX 76798, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"4697","DOI":"10.1039\/C7CS00837F","article-title":"Nanomaterial-based devices for point-of-care diagnostic applications","volume":"47","year":"2018","journal-title":"Chem. Soc. Rev."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"366","DOI":"10.1039\/C6CS00206D","article-title":"Photonic crystals: Emerging biosensors and their promise for point-of-care applications","volume":"46","author":"Inan","year":"2017","journal-title":"Chem. Soc. Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2313","DOI":"10.1128\/JCM.00476-17","article-title":"Point-of-Care Testing for Infectious Diseases: Past, Present, and Future","volume":"55","author":"Kozel","year":"2017","journal-title":"J. Clin. Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Hayes, B., Murphy, C., Crawley, A., and O\u2019Kennedy, R. (2018). Developments in Point-of-Care Diagnostic Technology for Cancer Detection. Diagnostics, 8.","DOI":"10.3390\/diagnostics8020039"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Hsieh, H., Jeffrey, D., and Bernhard, W. (2017). Analytical Tools to Improve Optimization Procedures for Lateral Flow Assays. Diagnostics, 7.","DOI":"10.3390\/diagnostics7020029"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"2118","DOI":"10.1039\/c2lc21204h","article-title":"Commercialization of microfluidic point-of-care diagnostic devices","volume":"12","author":"Chin","year":"2012","journal-title":"Lab Chip"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1169","DOI":"10.1016\/j.tibtech.2017.09.001","article-title":"Challenges of the nano-bio interface in lateral flow and dipstick immunoassays","volume":"35","author":"Bosch","year":"2017","journal-title":"Trends Biotechnol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"914","DOI":"10.2471\/BLT.12.102780","article-title":"Low-cost tools for diagnosing and monitoring HIV infection in low-resource settings","volume":"90","author":"Wu","year":"2012","journal-title":"Bull World Health Organ."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"577","DOI":"10.3390\/bios5030577","article-title":"Point-of-Care Diagnostics in Low Resource Settings: Present Status and Future Role of Microfluidics","volume":"5","author":"Sharma","year":"2015","journal-title":"Biosensors"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Cho, S., Brake, J.H., Joy, C., and Kim, S. (2015). Refractive index measurement using an optical cavity based biosensor with a differential detection. Proc. SPIE.","DOI":"10.1117\/12.2079300"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Rho, D., Cho, S., Joy, C., and Kim, S. (2015, January 23\u201324). Demonstration of an optical cavity sensor with a differential detection method by refractive index measurements. Proceedings of the 2015 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), Waco, TX, USA.","DOI":"10.1109\/WMCaS.2015.7233217"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Cowles, P., Joy, C., Bujana, A., Rho, D., and Kim, S. (2016). Preliminary measurement results of biotinylated BSA detection of a low cost optical cavity based biosensor using differential detection. Proc. SPIE.","DOI":"10.1117\/12.2212904"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Joy, C., and Kim, S. (2017, January 30\u201331). Benefits of a scaled differential calculation method for use in a Fabry-Perot based optical cavity biosensor. Proceedings of the 2017 Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), Waco, TX, USA.","DOI":"10.1109\/WMCaS.2017.8070707"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Rho, D., and Kim, S. (2017, January 11\u201315). Large dynamic range optical cavity based sensor using a low cost three-laser system. Proceedings of the 2017 39th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Jeju Island, Korea.","DOI":"10.1109\/EMBC.2017.8037093"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"11244","DOI":"10.1364\/OE.25.011244","article-title":"Low-cost optical cavity based sensor with a large dynamic range","volume":"25","author":"Rho","year":"2017","journal-title":"Opt. Express"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"18982","DOI":"10.1364\/OE.26.018982","article-title":"Label-free real-time detection of biotinylated bovine serum albumin using a low-cost optical cavity-based biosensor","volume":"26","author":"Rho","year":"2018","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"13880","DOI":"10.1364\/OE.23.013880","article-title":"High sensitivity refractive index sensor based on adiabatic tapered optical fiber deposited with nanofilm by ALD","volume":"23","author":"Zhu","year":"2015","journal-title":"Opt. Express"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e122","DOI":"10.1038\/lsa.2014.3","article-title":"Handheld high-throughput plasmonic biosensor using computational on-chip imaging","volume":"3","author":"Cetin","year":"2014","journal-title":"Light Sci Appl."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"51935","DOI":"10.1039\/C4RA09056J","article-title":"Capillarity driven (self-powered) one dimensional photonic crystals for refractometry and (bio)sensing applications","volume":"4","author":"Surdo","year":"2014","journal-title":"RSC Adv."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"6082","DOI":"10.1364\/OL.39.006082","article-title":"Liquid refractive index sensing independent of opacity using an optofluidic diffraction sensor","volume":"39","author":"Xu","year":"2014","journal-title":"Opt. Lett."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Sequeira, F., Duarte, D., Bilro, L., Rudnitskaya, A., Pesavento, M., Zeni, L., and Cennamo, N. (2016). Refractive Index Sensing with D-Shaped Plastic Optical Fibers for Chemical and Biochemical Applications. Sensors, 16.","DOI":"10.3390\/s16122119"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"4265","DOI":"10.1039\/C7LC00929A","article-title":"Asymmetric nanofluidic grating detector for differential refractive index measurement and biosensing","volume":"17","author":"Purr","year":"2017","journal-title":"Lab Chip"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"4470","DOI":"10.1364\/OL.42.004470","article-title":"In-fiber refractive index sensor based on single eccentric hole-assisted dual-core fiber","volume":"42","author":"Yang","year":"2017","journal-title":"Opt. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Yang, B., Yang, B., Zhang, J., Yin, Y., Niu, Y., and Ding, M. (2019). A Sensing Peak Identification Method for Fiber Extrinsic Fabry\u2013Perot Interferometric Refractive Index Sensing. Sensors, 19.","DOI":"10.3390\/s19010096"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Ashley, J., D\u2019Aurelio, R., Piekarska, M., Temblay, J., Pleasants, M., Trinh, L., and Tothill, I. (2018). Development of a \u03b2-Lactoglobulin Sensor Based on SPR for Milk Allergens Detection. Biosensors, 8.","DOI":"10.3390\/bios8020032"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/9\/2193\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:51:15Z","timestamp":1760187075000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/9\/2193"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,5,12]]},"references-count":25,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2019,5]]}},"alternative-id":["s19092193"],"URL":"https:\/\/doi.org\/10.3390\/s19092193","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,5,12]]}}}