Despite the long history, electrostatics is still challenging and exciting research subjects. Recently, electrokinetic phenomena such as electrophoresis and dielectrophoresis have found useful applications in biotechnology and nanotechnology. In our lab, we are involved in research subjects based on applied electrostatics for the cross-disciplinary area such as bio and nanotechnology. Especially, we currently focus on electrokinetic manipulation of micro and nano-scaled materials and its application for fabrication of chemical sensors.

Gas-insulated switch gear (GIS), which is filled with pressurized SF₆ gas for electrical insulation as well as for arc extinction, is widely used in electric power system in recent decades due to the compact size and high reliability. Despite the high reliability, insulation fault may still occur in the long lifetime of GIS (typically a few tens of years). So it is important to predict and avoid potential insulation fault in GIS. Partial discharge (PD) detection is an effective method to assess the insulation condition of GIS. We proposed a new detection method of PD occurring in SF₆†using a carbon nanotube (CNT) gas sensor, which was fabricated by a new method based on electrokinetic manipulation of CNTs under positive dielectrophoresis (DEP), which trapped CNTs onto the microelectrode (Fig.1). When PD was generated in SF₆, the electrical conductance of gas sensor gradually increased.

The electrokinetic manipulation of CNT is also applicable to fabrication of nanocomposite material, which contains CNT as nanofiller material, which can dramatically improve electrical and thermal conductivity of dielectric material. Fig.2 shows CNTs aligned under action of electrostatic force along the direction of external electric field. The aligned CNTs increase the electrical conductivity of the epoxy resin film by 3 orders of magnitude.