PDMS Deposition for Optical Devices by Dip-Pen Nanolithography

Dip-pen nanolithography (DPN) is a low-cost, versatile bench-top method for directly patterning materials on surfaces with sub-50 nm resolution; it involves the use of a cantilever tip to transfer a selected ink onto various surfaces to create predefined patterns. Many parameters may influence DPN quality, due to the variety of deposited and surface materials and the chemical interactions between them. DPN tip deposition of liquid inks is not yet well understood, due to the lack of thorough study of the various parameters that need to be controlled in order to achieve uniform patterning. In this research, the printing of polydimethylsiloxane (PDMS) lines and the control of their physical dimensions are investigated; the applied parameters are different humidity levels, n-hexane dilution proportions and different tip velocities. Numerous experiments accompanied by atomic force microscope measurements are conducted in order to derive a recommended recipe for the required dimensions of the printable lines. A practical aspect of the research is to assess the potential of the application of DPN for the fabrication of various optical devices, such as gratings and waveguides. In order to validate the theoretical results, PDMS printing over silicon is used to successfully produce an optical diffraction grating. (Figure presented.).