Abstract

Characterization and Modeling of Paper-based Bi-Material Actuator Cantilever; Application in Phosphate Detection

Amer Charbaji, PhD Holder, University of Rhode Island

Paper-based microfluidics provide a simple, inexpensive, and user friendly approach for a variety of applications, such as environmental monitoring, healthcare, food safety, and various other miscellaneous purposes. Paper-based devices are made up of several different sections and, depending on the application, may require the use of an actuator for proper control of flow time, reaction time, sample volume or the sequential loading of reagents. In our previous publication, we described a novel autonomously-activated bi-material actuator cantilever (B-MAC) that offers several unique advantages for use in paper-based microfluidic devices. The B-MAC allows for the autonomous operation of paper-based devices that require sequential and timed delivery of multiple reagents. It is also simple to fabricate, requires small sample volumes to operate, and has a quick response time. The B-MAC is made up of a strip of filter paper that is partially laminated on one side with tape. Once the filter paper side is exposed to a fluid, the cellulose fibers experience hygro-expansion, whereas the adjoining tape layer remains constant in length. This difference in the expansion behavior of the paper and tape cause the cantilever to bend in the direction of the tape layer as shown below and touch the stationary component (SC). The B-MAC has been shown to be applicable to 1D, 2D, and 3D lateral flow devices. In this study, the B-MAC will be assessed as a potential actuator to be used in a paper-based device for the sensitive detection of phosphate in water. The most commonly used method to determine soluble phosphate in water is based on the molybdenum blue reaction. This assay has been implemented on paper-based devices before and requires multi-step loading of reagents to improve sensitivity, shelf life, and to reduce auto-reduction of the reagents. Using B-MAC in a paper-based device for phosphate detection will allow the sequential loading of multiple reagents to perform the molybdenum blue assay to detect phosphate with minimal human intervention other than simply adding the sample fluid.