Fabrication of flexible microfluidic pipes with embedded metal electrodes based on electrohydrodynamic jet printing

Microfluidic chips have attracted increasing research attention in biology, chemistry, and medicine; in particular, microfluidic pipes containing metal electrodes have broad prospects in capillary electrophoresis, electrochemical microdetection, biomedical engineering, and flexible electronics. In this study, a simple on-demand method for fabricating arrayed flexible microfluidic pipes with embedded metal electrodes was proposed. The method is based on the direct-writing technology of electrohydrodynamic jet printing (E-jet), which is combined with the conventional mold turning and wet etching processes to obtain flexible microfluidic pipe arrays with embedded metal electrodes. First, a linear convex microstructure with a smooth surface (line width of 10–100 μm and aspect ratio >1:2) was prepared by stacking direct-writing polyvinyl alcohol fibers using the E-jet printing system with a linear rotation-receiving substrate to serve as a template. Using the template, the arrayed microfluidic channels were obtained. Second, a flexible metal patterned conductive electrode (line width <5 μm) was printed on the flexible microfluidic pipe array substrate using the E-jet printing system with a linear translation-receiving substrate and the wet etching process, with a direct-writing photoresist as the protective layer. Finally, the microfluidic pipes were electrically tested with different salt solution concentrations to verify the conductivity of the pipes and the metal electrode. The results indicate that the integrated manufacturing process based on the E-jet printing could be used to simply and efficiently fabricate flexible microfluidic pipe arrays embedded with gold electrodes on-demand and at a low cost. These arrays can be broadly applied in biomedical engineering and flexible electronics. © 2023 Chinese Academy of Sciences. All rights reserved.