Low-cost embossed-paper micro-channels for spontaneous capillary flow
Abstract
Hydrophilic porous substrates, in particular paper, are now widely used for the fabrication of microfluidic devices. These materials are very attractive because of their low-cost and their ability to generate capillary flow. Such materials avoid the need of external pressure sources or syringe pumps. However, capillary flows wicking a hydrophilic fiber matrix experience non-specific adsorption and depend on environmental conditions such as humidity. In this article a novel fabrication method is proposed to create low-cost embossed-paper microfluidic devices allowing for spontaneous capillary flow. Thus, embossing is used to design hollow microfluidic channels and chambers on a waterproof and hydrophilic paper surface. Because the hollow-channels obtained are fiber-free, the issues of imbibition are avoided. Besides, the paper surface being hydrophilic, the capillary flow in the embossed device is spontaneous. Thus, such microfluidic devices provide an efficient support to perform diagnostics in resource-poor settings. In this work, it is shown that a colorimetric glucose detection can be achieved using embossed-paper channels. The detection is achieved in twelve minutes, either by naked eyes or by analyzing pictures taking with a smartphone camera for quantification.