{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T04:01:03Z","timestamp":1779336063425,"version":"3.51.4"},"reference-count":44,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,3,4]],"date-time":"2021-03-04T00:00:00Z","timestamp":1614816000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100019341","name":"Shenzhen Scientific and Technological Foundation","doi-asserted-by":"publisher","award":["JCYJ20180504165801830"],"award-info":[{"award-number":["JCYJ20180504165801830"]}],"id":[{"id":"10.13039\/501100019341","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Regional Specialized Industry Development Program funded by the Ministry of SMEs and Startups","award":["S2933804"],"award-info":[{"award-number":["S2933804"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Polydimethylsiloxane (PDMS) is a polymer widely used for fabrication and prototyping of microfluidic chips. The porous matrix structure of PDMS allows small hydrophobic molecules including some fluorescent dyes to be readily absorbed to PDMS and results in high fluorescent background signals, thereby significantly decreasing the optical detection sensitivity. This makes it challenging to accurately detect the fluorescent signals from samples using PDMS devices. Here, we have utilized polytetrafluoroethylene (PTFE) to inhibit absorption of hydrophobic small molecules on PDMS. Nile red was used to analyze the effectiveness of the inhibition and the absorbed fluorescence intensities for 3% and 6% PTFE coating (7.7 \u00b1 1.0 and 6.6 \u00b1 0.2) was twofold lower compared to 1% and 2% PTFE coating results (17.2 \u00b1 0.5 and 15.4 \u00b1 0.5). When compared to the control (55.3 \u00b1 1.6), it was sevenfold lower in background fluorescent intensity. Furthermore, we validated the optimized PTFE coating condition using a PDMS bioreactor capable of locally stimulating cells during culture to quantitatively analyze the lipid production using Chlamydomonas reinhardtii CC-125. Three percent PTFE coating was selected as the optimal concentration as there was no significant difference between 3% and 6% PTFE coating. Intracellular lipid contents of the cells were successfully stained with Nile Red inside the bioreactor and 3% PTFE coating successfully minimized the background fluorescence noise, allowing strong optical lipid signal to be detected within the PDMS bioreactor comparable to that of off-chip, less than 1% difference.<\/jats:p>","DOI":"10.3390\/s21051754","type":"journal-article","created":{"date-parts":[[2021,3,5]],"date-time":"2021-03-05T00:39:07Z","timestamp":1614904747000},"page":"1754","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["Optimization of PTFE Coating on PDMS Surfaces for Inhibition of Hydrophobic Molecule Absorption for Increased Optical Detection Sensitivity"],"prefix":"10.3390","volume":"21","author":[{"given":"Junyi","family":"Yao","sequence":"first","affiliation":[{"name":"School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yiyang","family":"Guan","sequence":"additional","affiliation":[{"name":"School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yunhwan","family":"Park","sequence":"additional","affiliation":[{"name":"Division of Environmental Science &amp; Ecological Engineering, Korea University, Seoul 02841, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoon E","family":"Choi","sequence":"additional","affiliation":[{"name":"Division of Environmental Science &amp; Ecological Engineering, Korea University, Seoul 02841, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyun Soo","family":"Kim","sequence":"additional","affiliation":[{"name":"Daegu Research Center for Medical Devices and Rehabilitation, Korea Institute of Machinery and Materials, Daegu 42994, Korea"},{"name":"Department of Electronic Engineering, Kwangwoon University, Seoul 01897, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5704-726X","authenticated-orcid":false,"given":"Jaewon","family":"Park","sequence":"additional","affiliation":[{"name":"School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1002\/(SICI)1522-2683(20000101)21:1<27::AID-ELPS27>3.0.CO;2-C","article-title":"Fabrication of microfluidic systems in poly(dimethylsiloxane)","volume":"21","author":"McDonald","year":"2000","journal-title":"Electrophoresis"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4217","DOI":"10.1039\/c3lc50665g","article-title":"Microchemostat array with small-volume fraction replenishment for steady-state microbial culture","volume":"13","author":"Park","year":"2013","journal-title":"Lab Chip"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"808","DOI":"10.1109\/JMEMS.2009.2021821","article-title":"Whole-Cell Impedance Analysis for Highly and Poorly Metastatic Cancer Cells","volume":"18","author":"Younghak","year":"2009","journal-title":"J. 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