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

Summary

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 <10 µm were achieved.

Abstract

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 <10 µm, 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.

Introduction

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 µm- 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 practices^1,....

Protocol

1. Designing the MMAA

1. 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's tray, the total width (w), and length (l) of the tray.
   NOTE: As an example, the available UV light exposure system had inner tray dimensions of 5 inch (") x 5" x 0.25" with a 4" circular cut-out. The dimensions of the MMAA were then designed to be....

Results

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). 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 UV exp.......

Discussion

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.......

Materials

List of materials used in this article

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