Dielectrophoresis of nanoscale dsDNA and humidity effects on its   electrical conductivity
  The dielectrophoresis method for trapping and attaching nanoscale double-stranded DNA between nanoelectrodes was developed. The method gives a high yield of trapping single or a few molecules only which enables transport measurements at the single molecule level. Electrical conductivity of individual 140-nm-long DNA molecules was measured, showing insulating behavior in dry conditions. In contrast, clear enhancement of conductivity was observed in moist conditions, relating to the interplay between the conformation of DNA molecules and their conductivity. 
S. Tuukkanen, A. Kuzyk, J. J. Toppari, V. P. Hytonen, T. Ihalainen, P.   Torma