• KSBB Journal
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• v.21 no.5
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• pp.325-330
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• 2006

This study presents the characterization of an integrated portable microfluidic electrical detection system for fast and low volume immunoassay using polystyrene microbead, which are used as immobilization surfaces. In our chip, a filtration method using the microbead was adopted for sample immobilization and immunogold silver staining(IGSS) was used to increase the electrical signal. The chip is composed of an inexpensive and biocompatible Polydimethylsiloxane(PDMS) layer and Pyrex glass substrate. Platinum microelectrodes for electric signal detection were fabricated on the substrate and microchannel and pillar-type microfilters were formed in the PDMS layer. With a fabricated chip, we reacted antigen and antibody according to the procedures. Then, silver enhancer was injected to increase the size of nanogold particles tagged with the second antibody. As a result, microbeads were connected to each other and formed an electrical bridge between microelectrodes. Resistance measured through the electrodes showed a difference of two orders of magnitude between specific and nonspecific immuno-reactions. The detection limit was 10 ng/ml. The developed immunoassay chip reduced the total analysis time from 3 hours to 50 min. Fast and low-volume biochemical analysis has been successfully achieved with the developed microfilter and immuno-sensor chip, which is integrated to the microfluidic system.

• Membrane Journal
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• v.28 no.5
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• pp.307-319
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• 2018

Ion-exchange membrane (IEM) has fixed charge groups and is a separation membrane which is capable of selectively transporting ions of the opposite polarity. Recently, the interest in IEMs has been increasing as the importance of the desalination and energy conversion processes using them as the key components has increased. Since the IEMs determine the efficiency of the above process, it is necessary to improve the separation performance and durability of them and also to lower the expensive membrane price, which is a hindrance to the widening application of the IEM process. Therefore, it is urgent to develop high-performance and low-cost IEMs. Among various types of IEMs, pore-filled membranes prepared by filling ionomer into a porous polymer substrate are intermediate forms of homogeneous membranes and heterogeneous membranes. The production cost would be cheap like the case of heterogeneous membranes because of the use of inexpensive supports and the reduction of the amount used of raw materials, and at the same time, they exhibit excellent electrochemical characteristics close to homogeneous membranes. In this review, major research and development trends of pore-filled IEMs, which are attracting attention as high-performance and low-cost IEMs, have been summarized and reported according to the application fields.