Fabrication of carbon nanotube bridge in V-groove channel using Dielectrophoresis

Since their discovery in 1991, Carbon nanotubes (CNTs) are known to have unique electrical, mechanical and thermal properties and have been used at many applications. For using at applications, the manipulation of the CNTs is very important. Recently, Dielectrophoresis has attracted much interest for CNTs alignment and deposition on a desirable location, but all the work have been done on plane electrodes. In this work, We propose a novel fabrication method of carbon nanotube bridge in V-groove channel using dielectrophoresis. Compared to the case using plane electrode, this method has several advantages. The electrodes in V-groove channel provide high and parallel electric field and eliminate nonspecific CNTs deposition so that efficiency of CNTs alignment increases. V-groove channel was fabricated on silicon wafer by TMAH bulk etching. The gold electrodes were deposited in V-groove channel. To prepare the SWNTs suspension, SWNTs were dispersed in DI water with 0.1 wt% sodium dodecyl sulfate by sonication. A drop of suspension was introduced onto the electrodes and ac voltage was applied. When SWNTs alignment on a electrodes in V-groove is compared with that on a plane electrodes, SWNTs were aligned to electric field direction and formed SWNTs bundle bridges cross V-groove channel. These carbon nanotube bridges have diameter of 0.5-2 mum and length of 5~20 mum. We think that this phenomenon was happened by 3D electric field in V-groove channel. Because these bridges had regular shape and wide contact areas, these bridges can have uniform electric properties and lower contact resistance, but the phenomenon need a further theoretically studies. SWNTs bridges can be used in various sensors. Because sensor bridges were away from surface, effects of surface reduced and signal to noise ratio increased. High surface areas of SWNTs bridges can improve sensitivity of sensors, and embedded SWNTs bridges in microchannel can be easily used at various microfluidic applications - - without additional work.