Closed-loop control of silicon nanotweezers for improvement of sensitivity to mechanical stiffness measurement and bio-sensing on DNA molecules

In this work we show that implementation of closed-loop control to silicon nanotweezers improves the sensitivity of the tool for mechanical characterization of biological molecules. Micromachined tweezers have already been used for the characterization of mechanical properties of DNA molecules [1] as well as for the sensing of enzymatic reactions on DNA bundle [2], [3]. However the resolution of the experiments does not allow the sensing on single molecules. Hereafter we show theoretically and experimentally that, reducing the resonance frequency of the system by the implementation of a state feedback, the sensitivity to stiffness variation is enhanced. Such improvement leads to better resolution for detection of enzymatic reactions on DNA [4].