Authors: S. Biswas, M. Hirtz, S. Lenhert, H. Fuchs
Affilation: Karlsruhe Institute of Technology, Germany
Pages: 231 - 234
Keywords: dip-pen nanolithography, atomic force microscope, viscosity, frequency spectrum
The Dip-Pen Nanolithography (DPN) process uses a chemically coated scanning probe tip (the “pen”) to directly deposit a material (“ink”) with nanometer precision onto a substrate. Several experimental parameters have been observed to influence the ink transport in DPN. Among these, viscosity and density of the ink are the two important parameters which play a crucial role in ink transport in DPN. It is necessary to understand and control these parameters in order to optimize DPN processes for a particular application. Here we report on studies aimed at employing the atomic force microscope (AFM) to measure the viscosity of ink used for DPN. Generally, for DPN, the ink wells are filled with ink (biological molecules in chloroform) and the ink then gets transported to the micro channels from the ink reservoir. The ink wells are dried for few hours to allow for evaporating of the chloroform before using them for coating the tip. It is difficult to measure the viscosity of this ink using standard processes of measuring viscosity. Therefore, we have tried to find the viscosity of the ink by monitoring the change in resonace frequency of the cantilever, from that in air, vibrating in the ink solution.