Photolithography-free PDMS stamps for paper microdevice fabrication

Purpose - This paper aims to investigate the applicability of 3D-printed molds to be used as a substitute for photolithography in the formation of polymer-based stamps. It proposes leveraging 3D printing as a rapid prototyping tool to be applied to microfluidic fabrication. Design/methodology/approach - Different designs are created using computer-aided design (CAD) software and printed via Makerbot 3D printer. The molds serve as negative reliefs for a PDMS stamp. The stamp is used to apply paraffin wax to chromatography paper, creating hydrophobic barriers and hydrophilic channels. The minimum functional channel widths and barrier widths are determined for the method. Findings - The method is demonstrated to be effective for bypassing the more cost-prohibitive photolithography approach for rapid paper microdevice fabrication. This approach produces functional channels that can be used for on-chip analytical assays. The minimum functional barrier widths and minimum functional channel widths are in good agreement with other published methods for paper-based microchannel fabrication. Research limitations/implications - The approach cannot generate the high-resolution structures possible with photolithography. Therefore, if higher resolutions are needed for a particular application, this approach is not the best. Practical implications - The simplicity of the approach introduces an affordable method to create disposable devices that can be used at the point of testing. Originality/value - The paper satisfies a need for inexpensive, rapid prototyping of paper-based devices. The method is simple and can be used as a tool for introducing labs to microfluidics research.