Microfluidic paper-based analytical devices (?PADs) are rapidly developed to enable low-cost and easy diagnostics for improving human life However there is still rare analysis and application of ion concentration polarization (ICP) in a ?PAD In this thesis we use a facile experiment to demonstrate that the electroosmotic flow can take place on a ?PAD Moreover we are the first to measure the current-voltage curve of a Nafion-coated ?PAD demonstrating that ICP is occurring In addition we also use Scanning-electron microscope (SEM) to show the Nafion can fill the pores of paper providing ion-selective nano-junctions to the ?PADs Furthermore we not only electrokinetically demonstrate the feasibility of the sample preconcentration method in ?PADs but also design a convergent channel that has ability to enhance the focused concentration An optimal convergent channel in our devices was also obtained and it can reach a 20-fold improvement of fluorescein concentration from the initial concentration of 10?M within 130 s under 50 V The sample volume required is only 2?L and thereby providing a platform for the low-volume detections Improving the dispersion problem of the concentrated molecules is also discussed The highest concentration of the sample plug can be retained at the same location for an additional 10 to 20 s Finally we also use fluorescein isothiocyanate labelled bovine serum albumin (FITC-BSA) for demonstrating that proteins in diluted solution can be concentrated by a factor of 15 from the initial concentration of 10?M within 120 s under the application of 50 V on ?PADs for practical applications which can reach the goal of point-of-care (POC) benefiting human life especially for developing countries and resource-poor settings
Experimental Study of Sample Preconcentration on Paper-based Devices and Its Application to Proteins
浩軒, 卜. (Author). 2014 9月 1
學生論文: Master's Thesis