Nanofountain Probes for the Delivery of Molecular Inks

Nanofountain probes (NFPs) are atomic force microscopy (AFM) probes designed for direct-write delivery of liquid molecular “inks” with sub-100 nm resolution. Liquid inks’ stored in an on-chip reservoir are fed through integrated microchannels to apertured dispensing tips by capillary action. This allows continuous delivery either to a substrate for direct-write nanopatterning, or to a cell for in vitro injection. Recently a fourth generation of nanofountain probe with enhanced geometry was fabricated. Fluid flow models quantified how the probe dimensions affect directly the NFP patterning resolution. These results were implemented to the fabrication which will enable a sub-100 nm patterning resolution and reproducibility necessary for a viable large-scale nanomanufacturing. nanoparticles in aqueous suspension [6], thiols [1,3], and drug­coated nanodiamonds [7]. Piezoelectric positional control of the NFP by an AFM enables ultra­precise prescription of pattern geometry. The accuracy of the NFP combined with the broad range of molecular delivery capabilities enable studies at a truly single cell level through two modes of delivery: direct write nanopatterning, and direct in vitro injection (Figure 2). Figure 1: Schematic of the nanofountain probe. Liquid ink is stored in an on-chip reservoir and fed through enclosed microchannels to apertured writing tips by capillarity (inset, scale bar: 2 μm) [7]. Summary of Research: The nanofountain probe (NFP [1­3]) functions as a highly miniaturized fountain pen that can be used to deliver a variety of materials with precision in the 50 nm to 1 μm range. As in a conventional fountain pen, the liquid material to be delivered (the “ink”) is contained in a reservoir and flows through a channel to an apertured dispensing tip (Figure 1). Past demonstrations of direct­write nanopatterning include proteins [4] and DNA [5] in buffer solution, gold Figure 2: Schematic of the two modes of delivery for the NFP. (left) For direct-writing nanopatterning, the tip is brought into contact with the substrate where an ink meniscus forms (right) for in vitro cellular injection, the tip is introduced to the cell membrane [7].