Three-dimensional microfluidic devices fabricated in layered paper and tape
Andres W. Martinez, Scott T. Phillips, and George M. Whitesides
Soft Matter Keywords
Capillary Force. Microfluidics
This article describes a method for fabricating 3D microfluidic devices by stacking layers of patterned paper and double-sided adhesive tape. Paper-based 3D microfluidic devices have capabilities in microfluidics that are difficult to achieve using conventional open-channel microsystems made from glass or polymers. In particular, 3D paper-based devices wick fluids and distribute microliter volumes of samples from single inlet points into arrays of detection zones (with numbers up to thousands). This capability makes it possible to carry out a range of new analytical protocols simply and inexpensively (all on a piece of paper) without external pumps. We demonstrate a prototype 3D device that tests 4 different samples for up to 4 different analytes and displays the results of the assays in a side-by-side configuration for easy comparison. Three-dimensional paper-based microfluidic devices are especially appropriate for use in distributed healthcare in the developing world and in environmental monitoring and water analysis.
The authors here use SU8 photoresist to pattern paper with microchannels (basketweave pattern for example). A layer of tape cut with punched holes was then placed on top of the patterned paper. The holes were then filled cellulose paste in order to fill the voids created between adjacent paper layers by the tape's thickness. Although the holes in the tape provide the method for vertical fluid flow, a cavity would simply fill with water and remain stagnant with surface tension. A filling with cellulose paste would allow water to wick through this area. This process could be repeated many times over.