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11 April 2007 On-line carbon nanotube-based biosensors in microfluidic channels
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Highly aligned double wall carbon nanotubes (DWCNT) and multi-wall carbon nanotubes (MWCNT) were synthesized in the shape of towers and embedded into microchannels for use as a biosensor. The towers were fabricated on a substrate patterned in 1mm x 1mm blocks with 1 mm spacing between the blocks. Chemical vapor deposition was used for the nanotube synthesis process. Patterned towers up to 8 mm high were grown and easily peeled off the silicon substrate. A nanotube electrode was then soldered on printed circuit boards and epoxy was cast into the tower under pressure. After curing, the top of the tower was polished. RF-plasma at 13.56 MHz was used to enhance the electrocatalytic effect of the nanotube electrode by removing excess epoxy and exposing the ends of the nanotubes. Au particles were electrodeposited on the plasma treated tower electrode. Cyclic voltammetry (CV) for the reduction of 6 mM K3Fe(CN)6 (in a 1.0 M KNO3 supporting electrolyte) was performed to examine the redox behavior of the nanotube tower electrode. Next, a master mold for polydimethylsiloxane (PDMS) was patterned using SU-8 and then a Pt disk electrode was embedded into the PDMS. The final fluidic channel between the epoxy-nanotube electrode and PDMS was sealed using a UV-curing adhesive. Impedance between the Pt and nanotube electrodes was monitored while flowing different solutions and LNCaP prostate cells. The impedance changed in proportion to the concentration of cells in the solution. A needle-type composite microelectrode was then fabricated by injecting a carbon nanotube-epoxy solution into a pulled-glass tube. CV and differential pulse voltammetry (DPV) to detect dopamine were showed a highly linear response with a sensitivity 100 nA/mM. Based on the impedance results using the flowing cells and the CV and DPV results, carbon nanotube microelectrodes are a promising candidate for cancer cell detection and neurotransmitter detection.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
YeoHeung Yun, Zhongyun Dong, Vesselin N. Shanov, Adam Bange, William R. Heineman, H. Brian Halsall, Laura Conforti, Amit Bhattacharya, and Mark J. Schulz "On-line carbon nanotube-based biosensors in microfluidic channels", Proc. SPIE 6528, Nanosensors, Microsensors, and Biosensors and Systems 2007, 65280T (11 April 2007);


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