A Protein Preconcentration Platform Utilizing Dual Gate Structure and Ion-Selective Membrane

This study presents a protein preconcentration platform integrated into the microfluidic channel structure. The proposed chip consists of a dual gate preconcentration structure with the main microchannel for sample actuation and two sub-microchannels for depletion region generation. A submicron thick ion-selective membrane was created using the micro-flow patterning technique for electrical connectivity between the main channel and sub-channels. The experimental results show that the proposed chip works stably in two modes: depletion and enrichment. Under capillary electrophoresis and electroosmotic flows, proteins are preconcentrated at the boundary of the depletion region, known as the electro-kinetically trapping zone or concentration zone. Besides, the depletion zone’s size and the concentration region’s fluorescence intensity increased about 2.5 and 3 times according to the voltage difference between the two terminals of the sample channel. The experimental results demonstrate that it is possible to integrate the proposed protein preconcentration structure into a biomicrofluidic chip system for protein detection with low concentration.