Abstract
Three-dimensional (3D) printing will create a revolution in the field of microfluidics due to fabricating truly three-dimensional channels in a single step. During the 3D-printing process, sacrificial materials are usually needed to fulfill channels inside and support the printed chip outside. Removing sacrificial materials after printing is obviously crucial for applying these 3D printed chips to microfluidics. However, there are few standard methods to address this issue. In this paper, engineering techniques of removing outer and inner sacrificial materials were studied. Meanwhile, quantification methods of removal efficiency for outer and inner sacrificial materials were proposed, respectively. For outer sacrificial materials, a hot bath in vegetable oil can remove 89.9% ± 0.1% of sacrificial materials, which is better than mechanics removal, hot oven heating, and an ethanol bath. For inner sacrificial materials, injecting 70 °C vegetable oil for 720 min is an optimized approach because of the uniformly high transmittance (93.8% ± 6.8%) and no obvious deformation. For the industrialization of microfluidics, the cost-effective removing time is around 10 min, which considers the balance between time cost and chip transmittance. The optimized approach and quantification methods presented in this paper show general engineering sacrificial materials removal techniques, which promote removing sacrificial materials from 3D-printed microfluidics chips and take 3D printing a step further in microfluidic applications.
Highlights
The three-dimensional (3D) printing technique has emerged to improve the fabrication of microfluidic devices [1,2,3,4], which is believed to have created a revolution in microfluidics [5,6,7,8,9]. 3D printing, which does not depend on masks to create the microfluidic channels, takes inputs from computer-aided design (CAD) software, which is able to produce fully 3D objects [10,11,12,13]
Using a photopolymer inkjet printer to fabricate microfluidic chips, two types of sacrificial materials are added during the process
The microfluidic chips were treated by four methods to remove outer sacrificial materials
Summary
The three-dimensional (3D) printing technique has emerged to improve the fabrication of microfluidic devices [1,2,3,4], which is believed to have created a revolution in microfluidics [5,6,7,8,9]. 3D printing, which does not depend on masks to create the microfluidic channels, takes inputs from computer-aided design (CAD) software, which is able to produce fully 3D objects [10,11,12,13]. Outer sacrificial materials are added to support the structure of the chip outside and inner sacrificial materials are added to support the micro-channel inside. Sochol et al presented how to remove outer and inner sacrificial materials in a centimeter-sized channel of a 3D-printed component [18]. They used dye-colored fluids to validate the channel, but there were no quantification methods to evaluate the removal efficiency. To evaluate the different removing approaches, quantification methods of removal efficiency for removing outer and inner sacrificial materials are presented. The engineering techniques were tested and verified in several 3D-printed microfluidic chips with different micro-channel cross-sections
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