Simple reagent storage in polyester-paper hybrid microdevices for colorimetric detection

A challenge in developing microfluidic devices for fully portable and automated field analyses is the ability to integrate and store reagents in a stable form while maintaining a low cost for the system. Paper-based field-deployable devices are currently the most extensively explored platforms for field use; however, centrifugal devices offer a means for heightened device automation and portability. The basis for many field devices is chemical sensing via colorimetric reactions. Here, we describe the development of polyester-paper hybrid microfluidic devices using a fabrication method, compounded from the print, cut and laminate (PCL) technique, that allows for simple yet effective dry reagent storage for enhanced use with centrifugal or polymeric-based devices. We utilized various proof-of-principle colorimetric assays for multiple applications, including the analysis of total protein, serum albumin, cocaine, 2,4,6-trinitrotoluene (TNT) and iron content. Localized reagent integration facilitated by paper punches allowed for both reagent stability prior to reaction for storage, color stability post-reaction for image analysis, and was compatible for multi-step analyses. Qualitative and quantitative results were achieved with the broad range of sample applications trialed here, while still maintaining the ability for downstream processing.