A novel fabrication method for centimeter-long surface-micromachined nanochannels

Abstract

In this paper, we describe a robust low temperature fabrication method for centimeter-long surface-micromachined nanofluidic channels. Unlike conventional approaches, in this method we dry etch sacrificial layers to form the cavities of the channels from the side, thereby eliminating the length restriction intrinsic to a channel etch and release process. To characterize the process, we examine the deformation of the cross section of different width nanochannels due to stress gradient of the wall material. We calculate the maximum edge deformation of a 5 µm wide channel due to stress to be ∼18 nm. In addition, we modified the model describing the channel release process to account for the stress-induced deformation and compared the results with the experiment. Finally, to demonstrate the efficacy of the completed process, the nanochannels were successfully filled with ethanol and water, surface hydrophobicity was characterized by meniscus measurements of the filled fluid, and electroosmotic experiments were performed to determine the surface charge and other channel characteristics.