Three-dimensional atomic force microscopy based on tailored cantilever probe with flared tip

In order to meet the requirements of nondestructive testing of true 3D topography of micro-nano structures,a novel three-dimensional atomic force microscope(3D-AFM)based on flared tip is developed.A high-precision scanning platform is designed to achieve fast servo through moving probe and sample simultaneously,and several combined nanopositioning stages are used to guarantee linearity and orthogonality of displacement.To eliminate the signal deviation caused by AFM-head movement,a traceable optical lever system is designed for cantilever deformation detection.In addition,a method of tailoring the cantilever of commercial probe with flared tip is proposed to reduce the lateral force applied on the tip in measurement.The tailored probe is mounted on the 3D-AFM,and 3D imaging experiments are conducted on different samples by use of adaptive-angle scanning strategy.The results show the roob-mean-square value of the vertical displacement noise(RMS)of the prototype is less than 0.1 nm and the high/width measurement repeatability(peak-to-peak)is less than 2.5 nm.

Simultaneous, hybrid single-molecule method by optical tweezers and fluorescence

As studies on life sciences progress toward the single-molecule level,new experiments have put forward more requirements for simultaneously displaying the mechanical properties and conformational changes of biomolecules.Optical tweezers and fluorescence microscopy have been combined to solve this problem.The combination of instruments forms a new generation of hybrid single-molecule technology that breaks through the limitations of traditional biochemical analysis.Powerfulmanipulation and fluorescence visualization have beenwidely used,and these techniques provide new possibilities for studying complex biochemical reactions at the singlemolecule level.This paper explains the features of this combined technique,including the application characteristics of single-trap and dual-traps,the anti-bleaching method,and optical tweezers combined with epifluorescence,confocal fluorescence,total internal reflection fluorescence,and other fluorescence methods.Using typical experiments,we analyze technical solutions and explain the factors and principles that instrument designers should consider.This review aims to give an introduction to this novel fusion technology process and describe important biological results.