Surface roughness improvement of 3D printed microchannel

Abstract

3D printing technique for microfluidics provides a rapid and cost-effective manufacturing method in one step without considering the complex three-dimensional structures. Because of the layer-by-layer printing process, the microchannel was characterized with rough surface while lacking research on it. Currently, the surface roughness of microchannels is improved mainly by etching (solvent vapor or wet chemical etching), which has two disadvantages: material selectivity and channel openness. In this study, the Polydimethylsiloxane (PDMS) coating method was employed to improve the surface quality of 3D printed microchannels to address the problems mentioned above. The adhesion strength of PDMS on 3D printed substrate was tested. The method proposed in this paper not only reduced the surface roughness of the microchannel effectively (40 fold for circular microchannels) but also reduced the pressure drop of the PDMS coated microchannel by 63.7% and reduced the leakage rate of the 3D printed microvalve by 67%. Moreover, cell viability was tested to validate the feasibility of the method for biomedical and cell analysis applications. Due to the good adhesion properties of PDMS to most materials used in microfluidics, the surface treatment method proposed in this paper can be expanded to other rapid fabrication techniques for low-cost and high-quality microfluidics.