1 Department of Micro- and Nanotechnology, Technical University of Denmark2 Nano Bio Integrated Systems, Department of Micro- and Nanotechnology, Technical University of Denmark3 Copenhagen Center for Health Technology, Center, Technical University of Denmark
The study (and potential application) of diphenylalanine peptide nanotubes is a popular topic that in recent years has experienced a boost in activity. This activity has been propelled forward by new articles continuously being published presenting even more spectacular properties of the nanotube structures ranging from piezo electricity over semi conductance to fluorescence. If such peptide nanotubes could be controlled and incorporated in sensors such as a biological field effect transistor it would greatly reduce the fabrication costs while at the same time providing researchers with new and exciting possibilities. The major driving forces supporting the interest in the peptide nanotubes is the fast and simple assembly process combined with their remarkable stability towards alcohols, organic solvents, and biological analytes that was presented shortly after the self-assembling properties of the diphenylalanine peptide was reported. The self-assembly process of the peptide nanotubes is entropy driven relying solely on hydrophobic packing of the aminoacid side groups and - interactions of the phenyl rings as stabilizing entities. As such it seems surprising that the peptide nanotubes should be as stable as reported. In this work, a more detailed study has demonstrated that the peptide nanotubes dissolve in most liquids including water. Despite the solubility of the peptide nanotubes in most liquids they remain remarkable stable under bombardment with heavy ions in dry conditions. This makes the peptide nanotubes excellent candidates as a water soluble alternative to traditional photolithography masks. In the present work we have demonstrated a rapid and low cost fabrication of silicon nanowires, in which process the silicon nanowire was dened in a dry etching procedure masked by the peptide nanotubes. To utilize this fabrication approach a manipulation method capable of orienting the peptide nanotubes at wafer scale has been developed. Furthermore, we have demonstrated that the peptide nanotubes can be used as a lift o material for the fabrication of nanoslits in metal surfaces. The water solubility of the peptide nanotubes allow the patterning of polymer materials not compatible with the organic solvents (used to remove the photoresists in traditional microfabrication techniques). In the nal part of the project we have demonstrated a rapid and mild fabrication of conducting polymer nanowire devices and illustrated their potential use as sensitive temperature sensor.