"Liquid Spreading Along Open Nanofluidic Channels"

Antonio Checco, Brookhaven National Laboratory

We use non-contact Atomic Force Microscopy (AFM) to study the morphology of precursor films of a non-volatile liquid (squalane) spreading along “open” nanofluidic channels. The channels are composed of COOH terminated “wetting” stripes patterned on a CH₃ terminated “nonwetting” surface using AFM oxidative nanolithography. We demonstrate that AFM allows for time-resolved measurements of precursor film morphologies with unprecedented lateral resolution. Our results show that the precursor film is “truncated” near the microscopic contact line where the local film profile is parabolic in good agreement with a long standing theoretical prediction by Hervet and de Gennes. Far from the contact line, the film thickness increases linearly and it is found to depend on the amount of lateral confinement imposed by the nanochannels.