Abstract
With the dramatic increment of complexity, more microfluidic devices require 3D structures, such as multi-depth and -layer channels. The traditional multi-step photolithography is time-consuming and labor-intensive and also requires precise alignment during the fabrication of microfluidic devices. Here, we present an inexpensive, single-step, and rapid fabrication method for multi-depth microfluidic devices using a high-resolution liquid crystal display (LCD) stereolithographic (SLA) three-dimensional (3D) printing system. With the pixel size down to 47.25 μm, the feature resolutions in the horizontal and vertical directions are 150 μm and 50 μm, respectively. The multi-depth molds were successfully printed at the same time and the multi-depth features were transferred properly to the polydimethylsiloxane (PDMS) having multi-depth channels via soft lithography. A flow-focusing droplet generator with a multi-depth channel was fabricated using the presented 3D printing method. Experimental results show that the multi-depth channel could manipulate the morphology and size of droplets, which is desired for many engineering applications. Taken together, LCD SLA 3D printing is an excellent alternative method to the multi-step photolithography for the fabrication of multi-depth microfluidic devices. Taking the advantages of its controllability, cost-effectiveness, and acceptable resolution, LCD SLA 3D printing can have a great potential to fabricate 3D microfluidic devices.
Highlights
Three-dimensional (3D) printing, which is considered as the key technique for the 4th industrial revolution, uses computer-controlled processes to create a three-dimensional object in a layer-by-layer fashion [1]
The fabrication of complex 3D tissue-like composites with 3D bioprinting has been utilized for conducting fundamental research to investigate the microenvironmental factors regulating the development of cells and organs [2,3] and clinical therapies, such as artificial organs for transplantation [4,5]. 3D printing has been applied to the fabrication of microfluidic devices [6,7] in the form of microelectromechanical sensors and/or actuators that can process and analyze minuscule quantities of biomedical fluid samples in an inexpensive, accurate, fast, and customizable manner [8]
Microfluidic devices are fabricated through microfabrication processes which include fabricating a channel mold using photolithography, casting a channel device over the mold using soft lithography, and bonding the channel device onto a substrate [9,10]
Summary
Three-dimensional (3D) printing, which is considered as the key technique for the 4th industrial revolution, uses computer-controlled processes to create a three-dimensional object in a layer-by-layer fashion [1]. Such methods require multiple photolithography processes [23,24] and precise alignment [25], being labor-intensive and time-consuming methods With this in mind, we believe using 3D printing to print the multi-depth mold in a single step process will greatly benefit the development of complex 3D microfluidic devices. The LCD SLA 3D printer offers an inexpensive and rapid way to fabricate multi-depth microfluidic devices with a minimum feature size of approximately 150 μm. This technique is able to greatly simplify the fabrication of multi-depth microfluidic devices and benefit their applications
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