{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,18]],"date-time":"2025-10-18T20:57:26Z","timestamp":1760821046064,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2018,12,19]],"date-time":"2018-12-19T00:00:00Z","timestamp":1545177600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["16J12039","JP17H03196"],"award-info":[{"award-number":["16J12039","JP17H03196"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002241","name":"Japan Science and Technology Agency","doi-asserted-by":"publisher","award":["JPMJPR15R3"],"award-info":[{"award-number":["JPMJPR15R3"]}],"id":[{"id":"10.13039\/501100002241","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>Culturing cellular tissues inside a microchannel using an artificial three-dimensional (3D) microstructure is normally conducted to elucidate and reproduce a biological function. The thick photoresist SU-8, which has a microscale resolution and high aspect ratio, is widely used for the fabrication of microchannels and scaffolds having 3D structures for cell culture. However, it is difficult to accurately fabricate a mesh structure with a pore size that is smaller than the cells that has an overall height greater than 50 \u03bcm because of the deterioration of the verticality of exposure light and the diffusion of acid, which accelerates the crosslinking reaction in the SU-8 layer. In this study, we propose a method of integrating a vertical porous membrane into a microchannel. The resolution of the vertical porous membrane becomes more accurate through inclined oxygen ashing, without degrading the robustness. Because a single mask pattern is required for the proposed method, assembly error is not generated using the assembly-free process. The fabricated vertical porous membrane in the microchannel contained micropores that were smaller than the cells and sufficiently robust for a microfluidic system. HepG2 cells were attached three-dimensionally on the fabricated vertical porous membrane to demonstrate 3D cell culture.<\/jats:p>","DOI":"10.3390\/mi9120681","type":"journal-article","created":{"date-parts":[[2018,12,19]],"date-time":"2018-12-19T12:12:44Z","timestamp":1545221564000},"page":"681","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Integration Method of Microchannel and Vertical Micromesh Structure for Three-Dimensional Cell Culture Using Inclined Exposure and Inclined Oxygen Ashing"],"prefix":"10.3390","volume":"9","author":[{"given":"Hidetaka","family":"Ueno","sequence":"first","affiliation":[{"name":"Division of Mechanical Science and Technology, Gunma University, Kiryu 376-8515, Japan"}]},{"given":"Kou","family":"Yamada","sequence":"additional","affiliation":[{"name":"Division of Mechanical Science and Technology, Gunma University, Kiryu 376-8515, Japan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2574-7971","authenticated-orcid":false,"given":"Takaaki","family":"Suzuki","sequence":"additional","affiliation":[{"name":"Division of Mechanical Science and Technology, Gunma University, Kiryu 376-8515, Japan"},{"name":"JST, PRESTO, Kawaguchi 332-0012, Japan"}]}],"member":"1968","published-online":{"date-parts":[[2018,12,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1146\/annurev-bioeng-071910-124629","article-title":"The role of body-on-a-chip devices in drug and toxicity studies","volume":"13","author":"Esch","year":"2012","journal-title":"Annu. Rev. Biomed. Eng."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3081","DOI":"10.1039\/C4LC00371C","article-title":"Body-on-a-chip simulation with GI tract and liver tissue suggests that integrated nanoparticles have the potential to cause liver injury","volume":"14","author":"Esch","year":"2014","journal-title":"Lab Chip."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"590","DOI":"10.1021\/bp034238d","article-title":"Incorporation of 3T3-L1 cells to mimic bioaccumulation in a microscale cell culture analog device for toxicity studies","volume":"20","author":"Viravaidya","year":"2004","journal-title":"Biotech. Progr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"338","DOI":"10.1021\/bp034077d","article-title":"The design and fabrication of three-chamber microscale cell culture analog devices with integrated dissolved oxygen sensors","volume":"20","author":"Sin","year":"2004","journal-title":"Biotech. Progr."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2213","DOI":"10.1002\/bit.25989","article-title":"Design and demonstration of a pumpless 14 compartment microphysiological system","volume":"113","author":"Miller","year":"2016","journal-title":"Biotechnol. Bioeng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"584","DOI":"10.1038\/nmat3606","article-title":"Metre-long cell-laden microfibres exhibit tissue morphologies and functions","volume":"12","author":"Onoe","year":"2013","journal-title":"Nat. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1039\/B807585A","article-title":"Cell migration into scaffolds under co-culture conditions in a microfluidic platform","volume":"21","author":"Chung","year":"2009","journal-title":"Lab Chip."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"5168","DOI":"10.1038\/s41598-018-23512-1","article-title":"Engineered 3D vascular and neuronal networks in a microfluidic platform","volume":"8","author":"Osaki","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2719","DOI":"10.1039\/C6LC00461J","article-title":"Modular, pumpless body-on-a-chip platform for the co-culture of GI tract epithelium and 3D primary liver tissue","volume":"16","author":"Esch","year":"2016","journal-title":"Lab Chip."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1039\/C7LC00952F","article-title":"A multi-throughput multi-organ-on-a-chip system on a plate formatted pneumatic pressure-driven medium circulation platform","volume":"18","author":"Satoh","year":"2018","journal-title":"Lab Chip."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"790","DOI":"10.3390\/mi6060790","article-title":"Special Issue: 15 Years of SU-8 as MEMS Material","volume":"6","author":"Bertsch","year":"2015","journal-title":"Micromachines"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Zhou, Z.F., and Huang, Q.A. (2018). Comprehensive simulations for ultraviolet lithography process of thick SU-8 Photoresist. Micromachines, 9.","DOI":"10.3390\/mi9070341"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"408","DOI":"10.1016\/j.sna.2005.01.012","article-title":"Free-standing SU-8 microfluidic chips by adhesive bonding and release etching","volume":"120","author":"Tuomikoski","year":"2005","journal-title":"Sens. Actuator A"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1088\/0960-1317\/17\/6\/R01","article-title":"SU-8: A photoresist for high-aspect-ratio and 3D submicron lithography","volume":"17","author":"Campo","year":"2007","journal-title":"J. Micromech. Microeng."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1049\/mnl.2012.0216","article-title":"Cell Culture on MEMS Materials in Micro-Environment Limited by a Physical Condition","volume":"7","author":"Inoue","year":"2012","journal-title":"Micro Nano Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"523","DOI":"10.1016\/j.nimb.2007.06.012","article-title":"A SU-8 dish for cell irradiation","volume":"263","author":"Auzelyte","year":"2007","journal-title":"Nucl. Instrum. Methods Phys. Res. B"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4453","DOI":"10.1016\/j.msec.2013.07.001","article-title":"In vitro and in vivo evaluation of SU-8 biocompatibility","volume":"333","author":"Nemani","year":"2013","journal-title":"Mat. Sci. Eng. C"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"895","DOI":"10.1007\/s10544-012-9669-0","article-title":"On chip porous polymer membranes for integration of gastrointestinal tract epithelium with microfluidic \u2018body-on-a-chip\u2019 devices","volume":"14","author":"Esch","year":"2012","journal-title":"Biomed. Microdevices"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1149\/2.0091411jss","article-title":"Single- and multi-directional slanted plasma etching of silicon under practical plasma processing conditions","volume":"3","author":"Cho","year":"2014","journal-title":"ECS J. Solid State Sci. Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1662","DOI":"10.1126\/science.1188302","article-title":"Reconstituting organ-level lung functions on a chip","volume":"328","author":"Huh","year":"2010","journal-title":"Science"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"2165","DOI":"10.1039\/c2lc40074j","article-title":"Human gut-on-a-chip inhabited by microbial flora that experiences intestinal peristalsis-like motions and flow","volume":"12","author":"Kim","year":"2012","journal-title":"Lab Chip."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1126\/scitranslmed.3004249","article-title":"A human disease model of drug toxicity\u2013induced pulmonary edema in a lung-on-a-chip microdevice","volume":"4","author":"Huh","year":"2012","journal-title":"Sci. Transl. Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1121","DOI":"10.1109\/JMEMS.2006.879669","article-title":"Multidirectional UV lithography for complex 3-D MEMS structures","volume":"15","author":"Yoon","year":"2006","journal-title":"J. Microelectromech. Sys."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1016\/j.ab.2005.03.047","article-title":"Cytotoxicity test based on electrochemical impedance measurement of HepG2 cultured in microfabricated cell chip","volume":"341","author":"Yeon","year":"2005","journal-title":"Anal. Biochem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1254\/jphs.13135FP","article-title":"Evaluation of three-dimensional cultured HepG2 cells in a nano culture plate system: an in vitro human model of acetaminophen hepatotoxicity","volume":"124","author":"Aritomi","year":"2014","journal-title":"J. Pharmacol. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1016\/j.sna.2003.10.009","article-title":"In-channel 3-D micromesh structures using maskless multi-angle exposures and their microfilter application","volume":"111","author":"Sato","year":"2004","journal-title":"Sens. Actuator A"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3390\/mi6010001","article-title":"Innovative SU-8 lithography techniques and their applications","volume":"6","author":"Lee","year":"2015","journal-title":"Micromachines"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Suzuki, T., Yamamoto, H., Ohoka, M., Okonogi, A., Kabata, H., Kanno, I., Washizu, M., and Kotera, H. (2007). High throughput cell electroporation array fabricated by single-mask inclined UV lithography exposure and oxygen plasma etching. Transducers, 9828569.","DOI":"10.1109\/SENSOR.2007.4300223"},{"key":"ref_29","first-page":"3308","article-title":"Supercritical drying for water-rinsed resist systems","volume":"18","author":"Namatsu","year":"2000","journal-title":"Am. Vac. Soc."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1088\/0960-1317\/17\/3\/015","article-title":"Stability of the hydrophilic behaviour of oxygen plasma activated SU-8","volume":"17","author":"Walther","year":"2007","journal-title":"J. Micromech. Microengin."}],"container-title":["Micromachines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-666X\/9\/12\/681\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T15:35:03Z","timestamp":1760196903000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-666X\/9\/12\/681"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,12,19]]},"references-count":30,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2018,12]]}},"alternative-id":["mi9120681"],"URL":"https:\/\/doi.org\/10.3390\/mi9120681","relation":{},"ISSN":["2072-666X"],"issn-type":[{"type":"electronic","value":"2072-666X"}],"subject":[],"published":{"date-parts":[[2018,12,19]]}}}