Abstract
We report a novel method for fabrication of three-dimensional (3D) biocompatible micro-fluidic flow chambers in polydimethylsiloxane (PDMS) by 3D-printing water-soluble polyvinyl alcohol (PVA) filaments as master scaffolds. The scaffolds are first embedded in the PDMS and later residue-free dissolved in water leaving an inscription of the scaffolds in the hardened PDMS. We demonstrate the strength of our method using a regular, cheap 3D printer, and evaluate the inscription process and the channels micro-fluidic properties using image analysis and digital holographic microscopy. Furthermore, we provide a protocol that allows for direct printing on coverslips and we show that flow chambers with a channel cross section down to 40 μm × 300 μm can be realized within 60 min. These flow channels are perfectly transparent, biocompatible and can be used for microscopic applications without further treatment. Our proposed protocols facilitate an easy, fast and adaptable production of micro-fluidic channel designs that are cost-effective, do not require specialized training and can be used for a variety of cell and bacterial assays. To help readers reproduce our micro-fluidic devices, we provide: full preparation protocols, 3D-printing CAD files for channel scaffolds and our custom-made molding device, 3D printer build-plate leveling instructions, and G-code.
Highlights
Lab-on-a-chip (LOC) devices are commonly prototyped using polydimethylsiloxane (PDMS) since PDMS offers many desirable properties: easy usage, cheap production, swift integration of tubing, high light transparency, air-permeability and biocompatibility[1,2]
To achieve optimal printing accuracy and repeatability, we first level the build-plate of our 3D printer (Ultimaker 2+, Ultimaker, Netherlands)
We present protocols to fabricate micro-fluidic devices by embedding water-soluble 3D printed channel scaffolds in PDMS
Summary
Lab-on-a-chip (LOC) devices are commonly prototyped using polydimethylsiloxane (PDMS) since PDMS offers many desirable properties: easy usage, cheap production, swift integration of tubing, high light transparency, air-permeability and biocompatibility[1,2]. These devices are produced using soft lithography techniques by creating a silicon master pattern with a negative of the desired micro-fluidic channel[2,3]. The printouts were embedded in PDMS or epoxy resin and dissolved using acetone (ABS) or water (isomalt), leaving an imprint of the channel scaffold in the hardened PDMS or epoxy resin Using this fabrication procedure, micro-fluidic devices with reasonable biocompatibility and air-permeability can be realized. Our micro-fluidic devices are cheap, fast to produce, optically transparent, biocompatible, air-permeable, reproducible and tunable, allowing readers to change the channel design to fit their experimental requirements
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