Silicon Nanotweezers with Adjustable and Controllable Gap for the Manipulation and Characterization of DNA Molecules

We describe electrostatically actuated silicon nanotweezers which are intended for the manipulation and characterization of DNA molecules. The fabrication process combines KOH etching and deep reactive ion etching (DRIE) on silicon-on-insulator (SOI) wafer to form sharp nanotips and high aspect ratio microstructures, respectively. The microelectromechanical system (MEMS) consists of a pair of opposing tips, the distance of which can be accurately adjusted thanks to a high resolution differential capacitive sensor. The device shows a resolution of 5 nm for a displacement range of 3 μm (static mode). It has a resonant frequency at 2 kHz and a quality factor of 40 in air, and 550 in vacuum.