@article{84ad9acf68174363b0264d0c91c3dcdc,
title = "A simple low-temperature glass bonding process with surface activation by oxygen plasma for micro/nanofluidic devices",
abstract = "The bonding of glass substrates is necessary when constructing micro/nanofluidic devices for sealing micro- and nanochannels. Recently, a low-temperature glass bonding method utilizing surface activation with plasma was developed to realize micro/nanofluidic devices for various applications, but it still has issues for general use. Here, we propose a simple process of low-temperature glass bonding utilizing typical facilities available in clean rooms and applied it to the fabrication of micro/nanofluidic devices made of different glasses. In the process, the substrate surface was activated with oxygen plasma, and the glass substrates were placed in contact in a class ISO 5 clean room. The pre-bonded substrates were heated for annealing. We found an optimal concentration of oxygen plasma and achieved a bonding energy of 0.33-0.48 J/m2 in fused-silica/fused-silica glass bonding. The process was applied to the bonding of fused-silica glass and borosilicate glass, which is generally used in optical microscopy, and revealed higher bonding energy than fused-silica/fused-silica glass bonding. An annealing temperature lower than 200 °C was necessary to avoid crack generation by thermal stress due to the different thermal properties of the glasses. A fabricated micro/nanofluidic device exhibited a pressure resistance higher than 600 kPa. This work will contribute to the advancement of micro/nanofluidics.",
keywords = "Bonding, Fabrication, Glass, Microfluidics, Nanofluidics",
author = "Koki Shoda and Minori Tanaka and Kensuke Mino and Yutaka Kazoe",
note = "Funding Information: Funding: This research was funded by JSPS KAKENHI Grant Numbers JP19H02061, JP19K21930 and TEPCO Memorial Foundation. Funding Information: Acknowledgments: The authors would like to thank Kyojiro Morikawa at The University of Tokyo for his assistance in conducting experiments and fruitful discussion on the relationship between the bonding energy and the conditions of oxygen plasma and annealing. Fabrication facilities were provided in part by the Academic Consortium for Nano and Micro Fabrication of four universities (The University of Tokyo, Tokyo Institute of Technology, Keio University and Waseda University, JAPAN). This work was also conducted at Takeda Sentanchi Supercleanroom, The University of Tokyo, supported by “Nanotechnology Platform Program” of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, Grant Number JPMXP09F-19-UT-0109. Funding Information: This research was funded by JSPS KAKENHI Grant Numbers JP19H02061, JP19K21930 and TEPCO Memorial Foundation. The authors would like to thank Kyojiro Morikawa at The University of Tokyo for his assistance in conducting experiments and fruitful discussion on the relationship between the bonding energy and the conditions of oxygen plasma and annealing. Fabrication facilities were provided in part by the Academic Consortium for Nano and Micro Fabrication of four universities (The University of Tokyo, Tokyo Institute of Technology, Keio University and Waseda University, JAPAN). This work was also conducted at Takeda Sentanchi Supercleanroom, The University of Tokyo, supported by {"}Nanotechnology Platform Program{"} of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, Grant Number JPMXP09F-19-UT-0109. Publisher Copyright: {\textcopyright} 2020 by the authors.",
year = "2020",
month = sep,
doi = "10.3390/MI11090804",
language = "English",
volume = "11",
journal = "Micromachines",
issn = "2072-666X",
publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",
number = "9",
}