Name: design and development of a three-dimensionally printed microscope mask alignment adapter for the fabrication of multilayer microfluidic devices
Uploaded: 2021-01-25T13:00:00
Description: Watch this Scientific Journal Video about Design and Development of a Three-Dimensionally Printed Microscope Mask Alignment Adapter for the Fabrication of Multilayer Microfluidic Devices at JoVE.com

The authors would like to acknowledge the Center for Transformative Undergraduate Experiences from Texas Tech University for providing funding for this project. The authors would also like to acknowledge support from the Chemical Engineering Department at Texas Tech University.

1. Designing the MMAA
<ol>
	<li>Obtain the dimensions of the tray of the available UV light emission system to be the upper bound for the dimensions of the wafer holder (or UV exposure unit) shown in Figure 1. As shown in Figure 2A, measure the diameter (d) of the inner circular rim, the inner height (h) of the UV light emission system&#39;s tray, the total width (w), and length (l) of the tray. 
	NOTE: As an example, the available UV light exposure syste...

<ol>
	<li>Betancourt, T., Brannon-Peppas, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micro-+and+nanofabrication+methods+in+nanotechnological+medical+and+pharmaceutical+devices.">Micro- and nanofabrication methods in nanotechnological medical and pharmaceutical devices.</a> International Journal of Nanomedicine. 1 (4), 483-495 (2006).</li><li>Wheeler, A. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+device+for+single-cell+analysis.">Microfluidic device for single-cell analysis.</a> Analytical Chemistry. 75 (14), 3581-3586 (2003).</li><li>Kong, D. S., Carr, P. A., Chen, L., Zhang, S., Jacobson, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Parallel+gene+synthesis+in+a+microfluidic+device.">Parallel gene synthesis in a microfluidic device.</a> Nucleic Acids Research. 35 (8), 61 (2007).</li><li>Yang, M., Li, C. -. W., Yang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+docking+and+on-chip+monitoring+of+cellular+reactions+with+a+controlled+concentration+gradient+on+a+microfluidic+device.">Cell docking and on-chip monitoring of cellular reactions with a controlled concentration gradient on a microfluidic device.</a> Analytical Chemistry. 74 (16), 3991-4001 (2002).</li><li>Keles, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+robust+and+reusable+microreactor+employing+laser+based+mid-IR+chemical+imaging+for+the+automated+quantification+of+reaction+kinetics.">Development of a robust and reusable microreactor employing laser based mid-IR chemical imaging for the automated quantification of reaction kinetics.</a> Organic Process Research &amp; Development. 21 (11), 1761-1768 (2017).</li><li>Losey, M. W., Jackman, R. J., Firebaugh, S. L., Schmidt, M. A., Jensen, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+fabrication+of+microfluidic+devices+for+multiphase+mixing+and+reaction.">Design and fabrication of microfluidic devices for multiphase mixing and reaction.</a> Journal of Microelectromechanical Systems. 11 (6), 709-717 (2002).</li><li>Kobayashi, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microfluidic+device+for+conducting+gas-liquid-solid+hydrogenation+reactions.">A microfluidic device for conducting gas-liquid-solid hydrogenation reactions.</a> Science. 304 (5675), 1305-1308 (2004).</li><li>Shuler, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+organ-,+body-,+and+disease-on-a-chip+systems.">Advances in organ-, body-, and disease-on-a-chip systems.</a> Lab on a Chip. 19 (1), 9-10 (2019).</li><li>Kimura, H., Sakai, Y., Fujii, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organ/body-on-a-chip+based+on+microfluidic+technology+for+drug+discovery.">Organ/body-on-a-chip based on microfluidic technology for drug discovery.</a> Drug Metabolism and Pharmacokinetics. 33 (1), 43-48 (2018).</li><li>Lee, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+pumpless+Multi-Organ-on-a-Chip+(MOC)+combined+with+a+Pharmacokinetic-Pharmacodynamic+(PK-PD)+model.">A pumpless Multi-Organ-on-a-Chip (MOC) combined with a Pharmacokinetic-Pharmacodynamic (PK-PD) model.</a> Biotechnology and Bioengineering. 114 (2), 432-443 (2017).</li><li>Kang, S. -. W., Wang, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+soft+lithography+for+nano+functional+devices.">Application of soft lithography for nano functional devices.</a> Lithography. , 403-426 (2010).</li><li>Challa, P. K., Kartanas, T., Charmet, J., Knowles, T. P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+devices+fabricated+using+fast+wafer-scale+LED-lithography+patterning.">Microfluidic devices fabricated using fast wafer-scale LED-lithography patterning.</a> Biomicrofluidics. 11, 014113 (2017).</li><li>Li, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Desktop+aligner+for+fabrication+of+multilayer+microfluidic+devices.">Desktop aligner for fabrication of multilayer microfluidic devices.</a> Review of Scientific Instruments. 86 (7), 075008 (2015).</li><li>Pham, Q. L., Tong, N. -. A. N., Mathew, A., Voronov, R. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+compact+low-cost+low-maintenance+open+architecture+mask+aligner+for+fabrication+of+multilayer+microfluidics+devices.">A compact low-cost low-maintenance open architecture mask aligner for fabrication of multilayer microfluidics devices.</a> Biomicrofluidics. 12 (4), 044119 (2018).</li><li>Ravi, T., Ranganathan, R., Shunmugam, M. S., Kanthababu, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Topology+and+build+path+optimization+for+reducing+cost+in+FDM+uPrint+SE.">Topology and build path optimization for reducing cost in FDM uPrint SE.</a> Advances in Additive Manufacturing and Joining. , 189-198 (2019).</li><li>SU-8 Permanent Negative Epoxy Photoresist. Kayaku Advanced Materials Available from: <a target="_blank" href="https://kayakuam.com/wp-content/uploads/2020/09/KAM-SU-8-50-100-Datasheet-9.3.20-Final.pdf">https://kayakuam.com/wp-content/uploads/2020/09/KAM-SU-8-50-100-Datasheet-9.3.20-Final.pdf</a> (2020)</li></ol>

The aforementioned protocol outlines the procedure for 3D-printing an MMAA and using the system to create a precise, multilayer, microfluidic device master mold. Although the device is easy to use, there are critical steps within the protocol that require practice and care to ensure proper alignment of the master mold layers. The first critical step is the design of the MMAA. It is essential when designing the MMAA to determine the exact measurements for the device that will allow for a proper fit inside the UV light exp...

A well-developed and promising field in engineering research is microfabrication because of the vast expanse of applications employing microfluidic platforms. Microfabrication is a process wherein structures are produced with &#181;m- or smaller-sized features using different chemical compounds. As microfluidic research has developed over the last 30 years, soft lithography has become the most popular microfabrication technique with which to produce microchips made from poly(dimethylsiloxane) (PDMS) or similar substances. These microchips have been widely used for the miniaturization of common laboratory practices1,2,3,4 and have become powerful research tools for engineers to mimic reaction processes5,6,7, study reaction mechanisms, and mimic organs found in the human body in vitro (e.g., organ-on-a-chip)8,9,10. However, as the complexity of the application increases, it is typical that a more complex microfluidic device design allows for better replication of the real-life system it is intended to imitate.
The basic soft lithography procedure involves coating a substrate with a photoresist substance and placing a photomask over the coated substrate before subjecting the substrate to UV light11. The photomask has transparent regions that mimic the desired pattern of the microfluidic device channels. When subjecting the coated substrate to UV light, the transparent regions allow the UV light to penetrate through the photomask, causing the photoresist to be crosslinked. After the exposure step, the un-crosslinked photoresist is washed away using a developer, leaving solid structures with the intended pattern. As the complexity of the microfluidic devices becomes greater, they require multiple-layer construction with extremely precise dimensions. The process of multilayer microfabrication is much more difficult compared to single-layer microfabrication.
Multilayer microfabrication requires precise alignment of the first layer features with the designs on the second mask. Normally, this process is performed using a commercial mask aligner, which is expensive and requires training to operate the machinery. Thus, the process of multilayer microfabrication is typically unattainable for smaller laboratories that lack the funds or time for such endeavors. While several other custom-built mask aligners have been developed, these systems often require the purchase and assembly of many different parts and can still be quite complex12,13,14. This is not only expensive for smaller laboratories, but also requires time and training to build, understand, and use the system. The mask aligner detailed in this paper sought to alleviate these issues as there is no need for the purchase of additional equipment, only requiring equipment that is typically already present in laboratories that produce and use microfluidic devices. In addition, the mask aligner is fabricated by 3D printing, which with the recent advancement of 3D printing technology, has become readily available to most laboratories and universities at an affordable cost.
The protocol detailed in this paper aims to create a cost-effective and easy-operation alternative mask aligner. The mask aligner detailed herein can make multilayer microfabrication feasible for research laboratories without conventional fabrication facilities. Using the microscope mask alignment adapter (MMAA), functional microchips with complex features can be achieved using a regular UV light source, optical microscope, and common laboratory equipment. The results show that the MMAA performs well with an example system using an upright microscope and a UV light-exposure box. The MMAA produced using the 3D printing process was used to acquire a bilayer master mold of a herringbone microfluidic device with minimal alignment errors. Using the master mold fabricated with a 3D-printed MMAA, microfluidic devices were prepared with multilayered structures containing alignment errors of &#60;10 &#181;m. The alignment error of &#60;10 &#181;m is minimal enough to not hinder the application of the microfluidic device.
In addition, the successful alignment of a four-layer master mold produced using the MMAA was confirmed, and alignment errors were determined to be &#60;10 &#181;m. The functionality of the microfluidic device and minimal alignment errors validate the successful application of the MMAA in creating multilayer microfluidic devices. The MMAA can be customized to fit any microscope and UV exposure system by making minor changes to the file in the 3D printer. The following protocol outlines the steps necessary to fine-tune the MMAA to fit the equipment available in each laboratory and 3D-print the MMAA with the required specifications. In addition, the protocol details how to develop a multilayer master mold using the system and subsequently produce PDMS microfluidic devices using the master mold. Generation of the master mold and microfluidic chips then allows the user to test the effectiveness of the system.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Acrylonitrile Butadiene Styrene (ABS), 3D Printing Filament</td>
			<td></td>
			<td></td>
			<td>Provided by the Texas Tech University 3D printing facility</td>
		</tr>
		<tr>
			<td>BX53, Upright Microscope</td>
			<td>Olympus</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Form 2, Stereolithography 3D printer</td>
			<td>Formlabs</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Advanced Hot Plate Stirrer</td>
			<td>VWR</td>
			<td>97042-642</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoproyl Alcohol, 70% (v/v)</td>
			<td>VWR</td>
			<td>BDH7999-4</td>
			<td></td>
		</tr>
		<tr>
			<td>Light Colored Marker</td>
			<td>Sharpie</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Magnets, 3 mm x 3 mm</td>
			<td>WOTOY</td>
			<td></td>
			<td>ASIN #: B075PLVW8W</td>
		</tr>
		<tr>
			<td>SYLGARD 184 Silicone Elastomer Kit</td>
			<td>DOW</td>
			<td>4019862</td>
			<td></td>
		</tr>
		<tr>
			<td>Petri Dish, 150 mm x 15 mm</td>
			<td>VWR</td>
			<td>25384-326</td>
			<td></td>
		</tr>
		<tr>
			<td>Printed Photomasks</td>
			<td>CAD/Art Services, Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Aluminum Support Jack - 8&#34; x 8&#34;, Scissor Lift</td>
			<td>VWR</td>
			<td>12620-904</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicon Wafer</td>
			<td>University Wafer</td>
			<td>452</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Hydroxide</td>
			<td>VWR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sonication Bath</td>
			<td>Branson</td>
			<td>CPX3800H</td>
			<td></td>
		</tr>
		<tr>
			<td>Spin Coater</td>
			<td>Laurell Technologies Corporation</td>
			<td>Model WS-650MZ-23NPPB</td>
			<td></td>
		</tr>
		<tr>
			<td>STRATASYS SR-30</td>
			<td>MakerBot Industries, LLC</td>
			<td>SR-30</td>
			<td>Dissolvable support material for 3D printing</td>
		</tr>
		<tr>
			<td>Stratasys uPrint SE 3D Printer</td>
			<td>Computer Aided Technology, LLC</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>SU-8 50</td>
			<td>Kayaku</td>
			<td>Y131269 0500L1GL</td>
			<td></td>
		</tr>
		<tr>
			<td>SU-8 100</td>
			<td>Kayaku</td>
			<td>Y131273 0500L1GL</td>
			<td></td>
		</tr>
		<tr>
			<td>SU-8 Developer</td>
			<td>Kayaku</td>
			<td>Y020100 4000L1PE</td>
			<td></td>
		</tr>
		<tr>
			<td>Super glue</td>
			<td>Gorilla Glue</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Trichloro(1H,1H,2H,2H-perfluorooctyl)silane</td>
			<td>Sigma-Aldrich</td>
			<td>448931-10G</td>
			<td></td>
		</tr>
		<tr>
			<td>Tape</td>
			<td>Scotch</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Form Cure, UV Curing Chamber</td>
			<td>Formlabs</td>
			<td>FH-CU-01</td>
			<td></td>
		</tr>
		<tr>
			<td>UV-KUB2, UV Light-Exposure Box</td>
			<td>Kloe</td>
			<td>UV-KUB2</td>
			<td></td>
		</tr>
	</tbody>
</table>

design and development of a three-dimensionally printed microscope mask alignment adapter for the fabrication of multilayer microfluidic devices

This project aims to develop an easy-to-use and cost-effective platform for the fabrication of precise, multilayer microfluidic devices, which typically can only be achieved using costly equipment in a clean room setting. The key part of the platform is a three dimensionally (3D) printed microscope mask alignment adapter (MMAA) compatible with regular optical microscopes and ultraviolet (UV) light exposure systems. The overall process of creating the device has been vastly simplified because of the work done to optimize the device design. The process entails finding the proper dimensions for the equipment available in the laboratory and 3D-printing the MMAA with the optimized specifications. Experimental results show that the optimized MMAA designed and manufactured by 3D printing performs well with a common microscope and light exposure system. Using a master mold prepared by the 3D-printed MMAA, the resulting microfluidic devices with multilayered structures contain alignment errors of &lt;10 &#181;m, which is sufficient for common microchips. Although human error through transportation of the device to the UV light exposure system can cause larger fabrication errors, the minimal errors achieved in this study are attainable with practice and care. Furthermore, the MMAA can be customized to fit any microscope and UV exposure system by making changes to the modeling file in the 3D printing system. This project provides smaller laboratories with a useful research tool as it only requires the use of equipment that is typically already available to laboratories that produce and use microfluidic devices. The following detailed protocol outlines the design and 3D printing process for the MMAA. In addition, the steps for procuring a multilayer master mold using the MMAA and producing poly(dimethylsiloxane) (PDMS) microfluidic chips is also described herein.

Through the optimization and use of the MMAA (Figure 1), multilayer master molds with minimal alignment error were fabricated. The final MMAA was fabricated using the fused filament fabrication (FFF) 3D-printing process (Figure 2).&#160;The FFF process confers increased accuracy for the desired device dimensions. The MMAA consists of two main pieces (Figure 3): the base piece and the custom fastener. The base piece consists of the U...

Watch this Scientific Journal Video about Design and Development of a Three-Dimensionally Printed Microscope Mask Alignment Adapter for the Fabrication of Multilayer Microfluidic Devices at JoVE.com

Design and Development of a Three-Dimensionally Printed Microscope Mask Alignment Adapter for the Fabrication of Multilayer Microfluidic Devices

This project allows small laboratories to develop an easy-to-use platform for the fabrication of precise multilayer microfluidic devices. The platform consists of a three-dimensionally printed microscope mask alignment adapter using which multilayer microfluidic devices with alignment errors of &lt;10 &#181;m were achieved.

This project aims to develop an easy-to-use and cost-effective platform for the fabrication of precise, multilayer microfluidic devices, which typically ...

Research

JoVE Journal

Engineering

Design, Fabrication, and Experimental Characterization of Plasmonic Photoconductive Terahertz Emitters

In this video article we present a detailed demonstration of a highly efficient method for generating terahertz waves. Our technique is based on ...

Fabrication and Testing of Microfluidic Optomechanical Oscillators

Cavity optomechanics experiments that parametrically couple the phonon modes and photon modes have been investigated in various optical systems including ...

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

In Situ Time-dependent Dielectric Breakdown in the Transmission Electron Microscope: A Possibility to Understand the Failure Mechanism in Microelectronic Devices

The time-dependent dielectric breakdown (TDDB) in on-chip interconnect stacks is one of the most critical failure mechanisms for microelectronic devices. ...

Thermal Measurement Techniques in Analytical Microfluidic Devices

Thermal measurement techniques have been used for many applications such as thermal characterization of materials and chemical reaction detection. ...

Methods for Measuring the Orientation and Rotation Rate of 3D-printed Particles in Turbulence

Experimental methods are presented for measuring the rotational and translational motion of anisotropic particles in turbulent fluid flows. 3D printing ...

Fabrication and Operation of Acoustofluidic Devices Supporting Bulk Acoustic Standing Waves for Sheathless Focusing of Particles

Acoustophoresis refers to the displacement of suspended objects in response to directional forces from sound energy. Given that the suspended objects must ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Solvent Bonding for Fabrication of PMMA and COP Microfluidic Devices

Thermoplastic microfluidic devices offer many advantages over those made from silicone elastomers, but bonding procedures must be developed for each ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...

Design and Fabrication of an Optical Fiber Made of Water

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with ...