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Ahmed MAM, Jurczak KM, Lynn NS, Mulder JPSH, Verpoorte EMJ, Nagelkerke A. Rapid prototyping of PMMA-based microfluidic spheroid-on-a-chip models using micromilling and vapour-assisted thermal bonding. Sci Rep 2024; 14:2831. [PMID: 38310102 PMCID: PMC10838337 DOI: 10.1038/s41598-024-53266-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 01/30/2024] [Indexed: 02/05/2024] Open
Abstract
The application of microfluidic devices as next-generation cell and tissue culture systems has increased impressively in the last decades. With that, a plethora of materials as well as fabrication methods for these devices have emerged. Here, we describe the rapid prototyping of microfluidic devices, using micromilling and vapour-assisted thermal bonding of polymethyl methacrylate (PMMA), to create a spheroid-on-a-chip culture system. Surface roughness of the micromilled structures was assessed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), showing that the fabrication procedure can impact the surface quality of micromilled substrates with milling tracks that can be readily observed in micromilled channels. A roughness of approximately 153 nm was created. Chloroform vapour-assisted bonding was used for simultaneous surface smoothing and bonding. A 30-s treatment with chloroform-vapour was able to reduce the surface roughness and smooth it to approximately 39 nm roughness. Subsequent bonding of multilayer PMMA-based microfluidic chips created a durable assembly, as shown by tensile testing. MDA-MB-231 breast cancer cells were cultured as multicellular tumour spheroids in the device and their characteristics evaluated using immunofluorescence staining. Spheroids could be successfully maintained for at least three weeks. They consisted of a characteristic hypoxic core, along with expression of the quiescence marker, p27kip1. This core was surrounded by a ring of Ki67-positive, proliferative cells. Overall, the method described represents a versatile approach to generate microfluidic devices compatible with biological applications.
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Affiliation(s)
- Monieb A M Ahmed
- Pharmaceutical Analysis, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Klaudia M Jurczak
- W.J. Kolff Institute for Biomedical Engineering and Materials Science, University Medical Center Groningen, Groningen, The Netherlands
- Department of Surgery, University Medical Center Groningen, Groningen, The Netherlands
| | - N Scott Lynn
- Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic
| | - Jean-Paul S H Mulder
- Pharmaceutical Analysis, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Elisabeth M J Verpoorte
- Pharmaceutical Analysis, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands
| | - Anika Nagelkerke
- Pharmaceutical Analysis, Groningen Research Institute of Pharmacy, University of Groningen, Groningen, The Netherlands.
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Trinh KTL, Thai DA, Lee NY. Bonding Strategies for Thermoplastics Applicable for Bioanalysis and Diagnostics. MICROMACHINES 2022; 13:1503. [PMID: 36144126 PMCID: PMC9501821 DOI: 10.3390/mi13091503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 06/16/2023]
Abstract
Microfluidics is a multidisciplinary science that includes physics, chemistry, engineering, and biotechnology. Such microscale systems are receiving growing interest in applications such as analysis, diagnostics, and biomedical research. Thermoplastic polymers have emerged as one of the most attractive materials for microfluidic device fabrication owing to advantages such as being optically transparent, biocompatible, cost-effective, and mass producible. However, thermoplastic bonding is a key challenge for sealing microfluidic devices. Given the wide range of bonding methods, the appropriate bonding approach should be carefully selected depending on the thermoplastic material and functional requirements. In this review, we aim to provide a comprehensive overview of thermoplastic fabricating and bonding approaches, presenting their advantages and disadvantages, to assist in finding suitable microfluidic device bonding methods. In addition, we highlight current applications of thermoplastic microfluidics to analyses and diagnostics and introduce future perspectives on thermoplastic bonding strategies.
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Affiliation(s)
- Kieu The Loan Trinh
- Department of Industrial Environmental Engineering, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si 13120, Korea
| | - Duc Anh Thai
- Department of BioNano Technology, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si 13120, Korea
| | - Nae Yoon Lee
- Department of BioNano Technology, Gachon University, 1342 Seongnam-daero, Sujeong-gu, Seongnam-si 13120, Korea
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Giri K, Tsao CW. Recent Advances in Thermoplastic Microfluidic Bonding. MICROMACHINES 2022; 13:486. [PMID: 35334777 PMCID: PMC8949906 DOI: 10.3390/mi13030486] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 01/27/2023]
Abstract
Microfluidics is a multidisciplinary technology with applications in various fields, such as biomedical, energy, chemicals and environment. Thermoplastic is one of the most prominent materials for polymer microfluidics. Properties such as good mechanical rigidity, organic solvent resistivity, acid/base resistivity, and low water absorbance make thermoplastics suitable for various microfluidic applications. However, bonding of thermoplastics has always been challenging because of a wide range of bonding methods and requirements. This review paper summarizes the current bonding processes being practiced for the fabrication of thermoplastic microfluidic devices, and provides a comparison between the different bonding strategies to assist researchers in finding appropriate bonding methods for microfluidic device assembly.
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Affiliation(s)
| | - Chia-Wen Tsao
- Department of Mechanical Engineering, National Central University, Taoyuan City 320, Taiwan;
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Chen PC, Chen PT, Vo TNA. Using Stereolithographic Printing to Manufacture Monolithic Microfluidic Devices with an Extremely High Aspect Ratio. Polymers (Basel) 2021; 13:3750. [PMID: 34771305 PMCID: PMC8587111 DOI: 10.3390/polym13213750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/20/2021] [Accepted: 10/26/2021] [Indexed: 11/24/2022] Open
Abstract
Stereolithographic printing (SL) is widely used to create mini/microfluidic devices; however, the formation of microchannels smaller than 500 μm with good inner surface quality is still challenging due to the printing resolution of current commercial printers and the z-overcure error and scalloping phenomena. In the current study, we used SL printing to create microchannels with the aim of achieving a high degree of dimensional precision and a high-quality microchannel inner surface. Extensive experiments were performed and our results revealed the following: (1) the SL printing of microchannels can be implemented in three steps including channel layer printing, an oxygen inhibition process, and roof layer printing; (2) printing thickness should be reduced to minimize the scalloping phenomenon, which significantly improves dimensional accuracy and the quality of inner microchannel surfaces; (3) the inclusion of an oxygen inhibition step is a critical and efficient approach to suppressing the z-overcure error in order to eliminate the formation of in-channel obstructions; (4) microchannels with an extremely high aspect ratio of 40:1 (4000 μm in height and 100 μm in width) can be successfully manufactured within one hour by following the three-step printing process.
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Affiliation(s)
- Pin-Chuan Chen
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei City 106335, Taiwan; (P.-T.C.); (T.N.A.V.)
- High Speed 3D Printing Research Center, National Taiwan University of Science and Technology, Taipei City 106335, Taiwan
| | - Po-Tsang Chen
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei City 106335, Taiwan; (P.-T.C.); (T.N.A.V.)
| | - Tuan Ngoc Anh Vo
- Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei City 106335, Taiwan; (P.-T.C.); (T.N.A.V.)
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Ganser P, Baum C, Chargin D, Sauer-Budge AF, Sharon A. A practical approach for the optimization of channel integrity in the sealing of shallow microfluidic devices made from cyclic olefin polymer. Biomed Microdevices 2018; 20:24. [PMID: 29478142 DOI: 10.1007/s10544-018-0265-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A reduced channel height in microfluidic Lab-on-a-Chip (LOC) devices enables a reduction in the required volume of sample and reagents. LOC devices are most often manufactured by microstructuring a planar substrate and subsequently sealing it with a cover film. However, shallow chip designs, made from polymers, are sensitive to channel deformation during the sealing of the microfluidic device. Inappropriate bonding conditions often result in the loss of the microfluidic functionality. A systematic and practical approach for the identification of suitable bonding process parameters is missing. In this article, a straightforward approach for the optimization of channel integrity in the sealing of shallow microfluidic devices made from Cyclic Olefin Polymer (COP) is presented. Two COP materials were tested: COP Zeonex 690R (Glass transition temperature Tg = 135 °C) both as a cover film and substrate material, and COP ZF14 (Tg = 135 °C) as a film material. A mechanical analysis using microstructured Zeonex 690R substrates was performed to generate a matrix of low-distortion bonding parameters, including temperature, pressure and time. The well-established method of solvent-assisted bonding was used to enhance the characteristically low bond strengths of the native COP material. In addition, plasma-assisted bonding was tested and compared. The optimization approach was validated by the manufacture of a microfluidic test device, the demonstration of its microfluidic functionality, and the quantitative evaluation of the achieved channel integrity.
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Affiliation(s)
- Philipp Ganser
- Fraunhofer Institute for Production Technology IPT, Aachen, Germany
| | - Christoph Baum
- Fraunhofer Institute for Production Technology IPT, Aachen, Germany
| | - David Chargin
- Center for Manufacturing Innovation, Fraunhofer USA, Brookline, MA, 02446, USA
| | - Alexis F Sauer-Budge
- Center for Manufacturing Innovation, Fraunhofer USA, Brookline, MA, 02446, USA. .,Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA. .,Exponent Inc., Natick, MA, 01760, USA.
| | - Andre Sharon
- Center for Manufacturing Innovation, Fraunhofer USA, Brookline, MA, 02446, USA.,Department of Mechanical Engineering, Boston University, Boston, MA, 02215, USA
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Song IH, Park T. PMMA Solution Assisted Room Temperature Bonding for PMMA⁻PC Hybrid Devices. MICROMACHINES 2017; 8:mi8090284. [PMID: 30400474 PMCID: PMC6189942 DOI: 10.3390/mi8090284] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/15/2017] [Accepted: 09/17/2017] [Indexed: 11/16/2022]
Abstract
Recently, thermoplastic polymers have become popular materials for microfluidic chips due to their easy fabrication and low cost. A polymer based microfluidic device can be formed in various fabrication techniques such as laser machining, injection molding, and hot embossing. A new bonding process presented in this paper uses a 2.5% (w/w) polymethyl methacrylate (PMMA) solution as an adhesive layer to bond dissimilar polymers-PMMA to polycarbonate (PC)-to enclose the PMMA microfluidic channels with PC. This technique has been successfully demonstrated to bond PMMA microchip to PC film. This paper presents bonding strength using a shear strength test and a crack opening method in addition to the fluidic leakage inspection.
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Affiliation(s)
- In-Hyouk Song
- Department of Engineering Technology, Texas State University, San Marcos, TX 78666, USA.
| | - Taehyun Park
- School of Mechanical Engineering, Kyungnam University, Changwon 51767, Korea.
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Gong Y, Park JM, Lim J. An Interference-Assisted Thermal Bonding Method for the Fabrication of Thermoplastic Microfluidic Devices. MICROMACHINES 2016; 7:mi7110211. [PMID: 30404382 PMCID: PMC6189769 DOI: 10.3390/mi7110211] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/08/2016] [Accepted: 11/17/2016] [Indexed: 11/20/2022]
Abstract
Solutions for the bonding and sealing of micro-channels in the manufacturing process of microfluidic devices are limited; therefore, further technical developments are required to determine these solutions. In this study, a new bonding method for thermoplastic microfluidic devices was developed by combining an interference fit with a thermal treatment at low pressure. This involved a process of first injection molding thermoplastic substrates with a microchannel structure, and then performing bonding experiments at different bonding conditions. The results indicated the successful bonding of microchannels over a wide range of bonding pressures with the help of the interference fit. The study also determined additional advantages of the proposed bonding method by comparing the method with the conventional thermal bonding method.
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Affiliation(s)
- Yao Gong
- School of Mechanical Engineering, Yeungnam University, Daehakro 280, Gyeongsan, 38541 Gyeongbuk, Korea.
| | - Jang Min Park
- School of Mechanical Engineering, Yeungnam University, Daehakro 280, Gyeongsan, 38541 Gyeongbuk, Korea.
| | - Jiseok Lim
- School of Mechanical Engineering, Yeungnam University, Daehakro 280, Gyeongsan, 38541 Gyeongbuk, Korea.
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Takehara H, Nagaoka A, Noguchi J, Akagi T, Sakai T, Chung UI, Kasai H, Ichiki T. Implementation of tetra-poly(ethylene glycol) hydrogel with high mechanical strength into microfluidic device technology. BIOMICROFLUIDICS 2013; 7:54109. [PMID: 24404072 PMCID: PMC3795735 DOI: 10.1063/1.4822033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 09/10/2013] [Indexed: 05/27/2023]
Abstract
Hydrogels have several excellent characteristics suitable for biomedical use such as softness, biological inertness and solute permeability. Hence, integrating hydrogels into microfluidic devices is a promising approach for providing additional functions such as biocompatibility and porosity, to microfluidic devices. However, the poor mechanical strength of hydrogels has severely limited device design and fabrication. A tetra-poly(ethylene glycol) (tetra-PEG) hydrogel synthesized recently has high mechanical strength and is expected to overcome such a limitation. In this research, we have comprehensively studied the implementation of tetra-PEG gel into microfluidic device technology. First, the fabrication of tetra-PEG gel/PDMS hybrid microchannels was established by developing a simple and robust bonding technique. Second, some fundamental features of tetra-PEG gel/PDMS hybrid microchannels, particularly fluid flow and mass transfer, were studied. Finally, to demonstrate the unique application of tetra-PEG-gel-integrated microfluidic devices, the generation of patterned chemical modulation with the maximum concentration gradient: 10% per 20 μm in a hydrogel was performed. The techniques developed in this study are expected to provide fundamental and beneficial methods of developing various microfluidic devices for life science and biomedical applications.
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Affiliation(s)
- Hiroaki Takehara
- Department of Bioengineering, School of Engineering, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Akira Nagaoka
- Center for Disease Biology and Integrative Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Jun Noguchi
- Center for Disease Biology and Integrative Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Takanori Akagi
- Department of Bioengineering, School of Engineering, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Takamasa Sakai
- Department of Bioengineering, School of Engineering, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Ung-Il Chung
- Department of Bioengineering, School of Engineering, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan ; Center for Disease Biology and Integrative Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Haruo Kasai
- Center for Disease Biology and Integrative Medicine, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Takanori Ichiki
- Department of Bioengineering, School of Engineering, The University of Tokyo, 2-11-16, Yayoi, Bunkyo-ku, Tokyo, 113-8656, Japan
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Xiang A, Lei XY, Kang W, Zhao JR, Zhang J, Wang Q, Bao H, Yan Z, Guo YH. A novel combined capillary chip for rapid identification of gene mutation. RSC Adv 2013; 3:2437. [DOI: 10.1039/c2ra21934d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023] Open
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