Rapid Fabrication of Poly(methyl methacrylate) Devices for Lab-on-a-Chip Applications Using Acetic Acid and UV Treatment

Abstract

In the present study, we introduce a new approach for rapid bonding of poly(methyl methacrylate) (PMMA)-based microdevices using an acetic acid solvent with the assistance of UV irradiation. For the anticipated mechanism, acetic acid and UV irradiation induced free radicals on the PMMA surfaces, and acrylate monomers subsequently formed cross-links to create a permanent bonding between the PMMA substrates. PMMA devices effectively bonded within 30 s at a low pressure using clamps, and a clogging-free microchannel was achieved with the optimized 50% acetic acid. For surface characterizations, contact angle measurements and bonding performance analyses were conducted using predetermined acetic acid concentrations to optimize bonding conditions. In addition, the highest bond strength of bonded PMMA was approximately 11.75 MPa, which has not been reported before in the bonding of PMMA. A leak test was performed over 180 h to assess the robustness of the proposed method. Moreover, to promote the applicability of this bonding method, we tested two kinds of microfluidic device applications, including a cell culture-based device and a metal microelectrode-integrated device. The results showed that the cell culture-based application was highly biocompatible with the PMMA microdevices fabricated using an acetic acid solvent. Moreover, the low pressure required during the bonding process supported the integration of metal microelectrodes with the PMMA microdevice without any damage to the metal films. This novel bonding method holds great potential in the ecofriendly and rapid fabrication of microfluidic devices using PMMA.

Pressure-Free Assembling of Poly(methyl methacrylate) Microdevices via Microwave-Assisted Solvent Bonding and Its Biomedical Applications

“…Briefly, the bond strengths increased with the increasing acetic acid concentration, which was indicated by the measured values of 6.26 ± 0.97, 11.05 ± 1.69, and 14.95 ± 0.77 MPa for 50, 60, and 70% acetic acid, respectively. The highest bond strength of 14.95 ± 0.77 MPa obtained using 70% acetic acid was greater than that obtained in previous studies for bonding PMMA microdevices [ 18 , 19 ]. However, to avoid clogging of the microchannels, 60% acetic acid was chosen as the best bonding condition for future experiments.…”

“…In other words, bond strengths for PMMAs bonded with 50–70% acetic acid with an overlapped length of more than 1.5 mm could not be measured. When bonding with acetic acid and a microwave, the overlapped length had to be much smaller than in previous studies [ 18 , 19 ], otherwise the bonded PMMAs failed to detach. Figure 4 f shows the bond strength after bonding using 50–70% acetic acid.…”

“…In previous studies, we replaced commonly used solvents such as acetone, ethanol, or an ethanol/isopropyl alcohol mixture with a dilute acetic acid solution, which resulted in clog-free and deformation-free assembly of PMMA microdevices without the need for any other protective coating material. By using the diluted acetic acid solution, PMMA microdevices were successfully bonded within 20 min at room temperature, or merely 30 s under UV treatment [ 18 , 19 ].…”

“…The peripheral groove at the microdevice’s boundary was engraved to efficiently retain acetic acid during microwave irradiation and thus prevent evaporation, resulting in uniform bonding across the entire surface [ 25 ]. Acetic acid-assisted bonding was exploited in our previous studies both in room temperature condition or under UV irradiation for the fabrication of the PMMA microdevices with reliable bonding performance, but the PMMAs were pressurized during the bonding process [ 18 , 19 ]. Surprisingly, the use of a common household microwave and peripheral grooves in this study eliminated the need for clamps or other microwave absorbers like polymers or metals for the stable bonding of PMMAs.…”

Surface Modification Techniques for Endothelial Cell Seeding in PDMS Microfluidic Devices

“…Successful cell culture in microfluidic devices depend on the characteristics of the substrate materials. A broad range of polymers, such as polycarbonate [ 3 ], polystyrene [ 4 ], polymethyl-methacrylate [ 5 , 6 ], cyclic olefin polymers [ 7 , 8 ], and polydimethylsiloxane (PDMS) [ 9 , 10 , 11 , 12 , 13 ] have been used for fabricating microfluidic cell culture devices. Among them, PDMS has been gaining popularity because of the relatively low-cost and easy fabrication procedures as well as good mechanical stability [ 14 ].…”