Measurement of mass transfer during dip-pen nanolithography with phospholipids

Dip-pen nanolithography (DPN) has been extensively used before for patterning surfaces; however a complete understanding of the ink transport mechanisms is still lacking. Moreover, quality control of the fabricated structures is a bottleneck in DPN fabrication, and one aspect of this is the quantification of the ink mass transfer to the substrate during the lithographic process. There is a demand for measuring the exact amount of molecules deposited on a surface by lithographic methods, especially for biological applications. This article demonstrates a quantitative method for measuring the amount of ink transferred onto the substrate in DPN with phospholipids by dynamic force spectroscopy. To achieve this, the harmonic oscillation of a microcantilever in an atomic force microscope is used, obtaining picogram mass sensitivity in the determination of mass deposition.