Microparticle filtration using carbon nanotubes and impedance characterisation for gold microelectrodes sensor system
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1205-L09-12
Microparticle filtration using carbon nanotubes and impedance characterisation for gold microelectrodes sensor system A. Mathur, E.M. Hamad, S. Mukhopadhyay, S. S. Roy* and J. A. McLaughlin Nanotechnology and Integrated Bio-Engineering Research Centre, School of Engineering, University of Ulster, Newtownabbey, BT37 0QB, UK ABSTRACT Blood-cell-free serum is required for most clinical chemistry tests. At present bend micro channel and polymeric pillars are used in polymer based microfluidic devices (such as PMMA) for the blood filtration. In this study, we have fabricated carbon nanotube (CNT) pillars on silicon from 20-50 µm in diameter with ~10 µm spacing and integrate them inside the microfluidic channel with a view of using these for blood plasma filtration from whole blood, with passive capillary flow. Our main objective is to design a novel sensor, comprising CNT arrays, to filter/control whole blood flow, with an integrated micro patterned gold electrode which will be sealed by bonding into microfluidics structures. We have characterized the microfluidic channel by measuring the meniscus movement profiles. Also gold inter-digitated electrodes (IDEs) were fabricated on glass and immobilized with an antibody. These IDEs were used as an impedance-based biosensor using label-free antigen – antibody interaction. At a fixed frequency, the IDEs gave a linear response across the range of concentrations of secondary antibodies investigated (0 to 500 µg/mL). Keywords: Hot embossing, Carbon nanotubes (CNTs), Poly Methyl Meth Acralate (PMMA), bio-sensing. *Corresponding author: [email protected] INTRODUCTION Impedance-based biosensors, based on an electrochemical impedance spectroscopy (EIS), measure the electrical impedance of an interface in AC steady state, with variable frequency but constant low amplitude DC bias conditions to avoid disturbing the probe layer [1]. A major advantage of impedance-based biosensors over most other types is their ability to perform label free detection, whereas bio-molecule labelling can drastically change its binding properties [2]. Also, the yield of the target-label coupling reaction is highly variable; which is especially problematic for protein targets. Label-free operation offers additional advantages over endpoint detection in that it enables detection of target-probe binding in real time which can improve measurement accuracy and allows determination of affinity constants [3]. The remarkable properties of carbon nanotubes have motivated much research on their processing, integration, and applications. The incorporation of CNTs onto polymeric substrates provides a wide range of applications in various areas such as microfluidics, flexible microdevices, field emission and micro/nano electronics etc. Due to the low glass transition temperatures of most of the polymers it is extremely difficult to synthesize high quality CNTs directly on them. Various techniques like solution-based processing, soft lithography, casting into PDMS and hot embossing have been developed
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