The evolution of fountain pen nanolithography: Controlled multi- probe delivery of liquids and gases

Nanolithography is a challenge that always needs to advance with new methods, materials, scales and generality of application in order to achieve progress in both technology and fundamental science. This article focuses on the unique capabilities of fountain pen nanolithography (FPN), a method that is based on atomic force microscopic (AFM) technology for nanoprinting. The technique allows for working in ambient conditions while seeing "online" the printing area under a standard upright microscope. FPN can be used for direct deposition of a variety of inks, from single molecules to particles that can be hundreds of nanometers and even cells. Also demonstrated in this paper is the ability to deliver gas inks for nanochemical/ nanophysical changes. The technique allows for control of better than 50 nm in line widths and close to a nanometer in height. Different hydrophilic levels of flat surfaces and also complex structures have been used for the nanoprinting. The writing control is achieved using different modes of operation and set-points and also includes the application of voltage or pressure during the printing process. Wetting phenomena on the nanoscale are shown to be of fundamental importance in FPN.