Twin cantilevers with a nanogap for single molecule experimentation

Single molecule experiments aimed both at fundamental investigation and applications, have been, recently, attracting a lot of attention. Most of the devices used for the detection and the manipulation of single molecules are based on very expensive lithographic tools, need a specific molecule labelling or functionalization and still show many limitations. We propose here an alternative approach based on the fabrication of pair of identical silicon cantilevers (the twin cantilevers), separated by a gap that is tuneable on the nanometric scale. The fabrication and operation of our twin cantilever device involves only the use of standard optical lithography and micrometric manipulation. We have investigated the frequency response of the twin cantilever device around its fundamental resonance, and, by modelling its behaviour, we show that a single molecule, spanning the cantilever gap, can, on paper, be detected

Reversible switching between superhydrophobic states on a hierarchically structured surface

Nature offers exciting examples for functional wetting properties based on superhydrophobicity, such as the self-cleaning surfaces on plant leaves and trapped air on immersed insect surfaces allowing underwater breathing. They inspire biomimetic approaches in science and technology. Superhydrophobicity relies on the Cassie wetting state where air is trapped within the surface topography. Pressure can trigger an irreversible transition from the Cassie state to the Wenzel state with no trapped air—this transition is usually detrimental for nonwetting functionality and is to be avoided. Here we present a new type of reversible, localized and instantaneous transition between two Cassie wetting states, enabled by two-level (dual-scale) topography of a superhydrophobic surface, that allows writing, erasing, rewriting and storing of optically displayed information in plastrons related to different length scales