Flexible paper-based devices nanofunctionalized with polydopamine for the transport of microfluids
In this work we propose the construction of flexible devices functionalized with polydopamine for transporting microfluids, based on paper substrates and functionalized with organic polydopamine polymer. Due to their low cost and easy handling, paper-based devices are competitive with traditional devices made of glass or metal substrates, whereas polydopamine, a polymer used to functionalize the device in this work, is very promising for application in different sectors due to its biocompatibility and ease of adhesion on surfaces with different characteristics. Hydrophilic polydopamine tracks with controlled thickness were formed on hydrophobic papers to accelerate the flow of aqueous microfluids. The fluid roll angle was about twice smaller when compared to non-functionalized control devices. The characterization of the built device was monitored using the techniques of: surface analysis using Confocal Laser Scanning Microscope, Atomic Force Microscopy (AFM) and Infrared Atomic Force Microscopy (AFM-IR) for images and surface chemical composition, and contact angle for hydrophilicity. As a proof of concept, a water-based ink containing carbon black was adapted for transport on the functionalized surface with polydopamine. The conductive ink was successfully deposited on the surface of the substrate, forming conductive tracks with the potential to be explored in the area of electrical and electrochemical devices.