Three-dimensional microfluidic devices fabricated in layered paper and tape

Abstract

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.diagnostics ͉ patterned paper D iagnostic devices for the developing world must be inexpensive, rugged, lightweight, and independent of supporting infrastructure (1-7). Among the most successful of current systems are those that rely on lateral movement of fluids across paper strips to distribute reagents (e.g., dipsticks and lateral flow systems) (2, 6). These systems are useful, but limited in their capabilities (2, 7). This articles describes a new class of analytical devices fabricated by layering paper patterned into hydrophilic channels and hydrophobic walls (1,8,9) and tape patterned with holes that connect channels in different layers of paper. These devices extend paper-based assays from simple 1D lateral-flow systems to 3D devices with complex microfluidic paths, and expand significantly the capabilities of very low-cost analytical systems. There are many examples of 3D polymeric or glass microfluidic systems (10-14), but 3D paper-based systems combine simplicity in fabrication, complexity in fluidic and bioanalytical capability, and low cost. We believe they will be useful in a variety of applications, including diagnostics for developing economies, drug development, and environmental monitoring.We call these devices 3D microfluidic paper analytical devices (PADs). They distribute fluids both vertically and laterally, and they enable streams of fluid to cross one another without mixing. These devices use capillary wicking to distribute fluids into complex arrays of tens to thousands of detection zones in times of seconds to minutes (depending on the architecture of the device, and the choice of materials). The devices are small (Ͻ10-cm 2 footprint), lightweight (0.15 g⅐cm Ϫ2 ), and are easy to stack, store, and transport; they do not require external pumps, and they are thus appropriate for applications in: (i) innovative developing countries (IDCs) (15), as diagnostic and analytical devices that could be combined with telemedicine (1); (ii) array-based analytical systems in the pharma...

Paper‐Based Electrodes for Flexible Energy Storage Devices

“…Since 1960s, paper has been researched and employed as substrates for a diverse array of electronics, namely paper electronics,34 including displays,35 sensors,36, 37 transistors,38 radiofrequency identification devices,39 generators,40, 41 light‐emitting diodes,42 etc. Papers are promising electrode materials because of their wide availability, low cost, light weight, environmental friendliness, recyclability and bendability 14, 34, 43, 44, 45, 46.…”

From the Bench to the Field in Low‐Cost Diagnostics: Two Case Studies

“…The Whitesides group had developed the initial idea of 3D paper microfluidic devices that formed the technical starting point for the development of the test for liver function. [7,[36][37][38][39] Diagnostics for All Inc. (DFA) was formed as a non-profit (501-c-3) engineering organization to develop paper-based devices-or indeed, any type of device that suits a task-as diagnostics. Academic groups excel at basic research and innovation, but usually lack the proper resources, incentives, motivation, and experience to do the detail-oriented engineering required to execute trials, regulatory clearance, manufacturing, and quality-control for a product.…”

Analytical Devices Based on Direct Synthesis of DNA on Paper

“…The first approach has received significant attention following the development of 3D µPADs-systems which distribute the sample via vertical flow to independent test zones that store distinct reagents. [11,13] The second approach has, so far, been largely ignored, probably due to the scarcity of methods available for assembling high quality microarrays on paper. To enable sensitive assays, these microarrays must be immobilized (preferably covalently, or, if noncovalent, with very low dissociation constants) and at high density on the surface of the substrate.…”