Guangyong Li

Assembly of nanostructure using AFM based nanomanipulation system

Assembly of nano-structures involves manipulation of nanoparticles, nano-rods, nanowires and nanotubes. Modelling the behavior of a nano-rod or a nanotube pushed by an AFM tip is much more complex than that of a nano-particle because in the case of the nano-particle usually only translation occurs while for the nano-rod and nanotube both translational and rotational motion occurs during manipulation. In this work, the behavior of nano-rods under pushing is theoretically analyzed and the interaction among tip, substrate and nano-rods has been modelled. Based on these models, the real-time interactive forces are used to update the AFM image. The real-time visual display combined with the real-time force feedback provides an augmented reality environment in which the operator not only can feel the interaction forces but can also observe the real-time changes of the nano-environment. The new developed augmented reality system capable of manipulating not only nanoparticles but also nano-rods makes nano-assembly using AFM based nanomanipulation system feasible and applicable.

Augmented reality system for real-time nanomanipulation

By introducing haptic force feedback, nanomanipulation using the AFM becomes easier. However, this technique has been impeded by tip displacement due to the softness of AFM cantilever. In this paper, a novel nanomanipulation system assisted by augmented reality is presented. By analyzing the cantilever-tip interaction with the environment, the normal force and the lateral force are obtained. These forces are then fed to a haptic device to provide real-time force feedback for operator. The visual images are also updated based on real-time force and position information, which provides the operator with real-time visual feedback. New calibration methods and compensation algorithm are introduced to compensate for the tip displacement, therefore, the visual display and force feeling from the haptic device become reliable. The real-time force feedback and the real-time visual display provide the operator with an augmented reality environment. Experimental results have verified the effectiveness of the proposed novel augmented reality system.

Calibration of a micromanipulation system

Calibration is indispensable for automatic micromanipulation. In this paper, using the height difference between different focus planes detected from the microscope and the coordinates of the probe measured from encoders, systematic methods to calibrate the relative position and orientation between the tools and the microscope are developed. Using the least square error (LSE) method to process the data measured, the influence of various positioning errors can be reduced. Experiments are performed to calibrate a micromanipulation system using the proposed methods. The calibration results are validated by cross verification through further experiments.

Nano-assembly of DNA based electronic devices using atomic force microscopy

DNA electronics circuits require an efficient way to accurately position and individually manipulate DNA molecules. The recent development of atomic force microscopy (AFM) seems to be a promising solution. We have recently developed an AFM based augmented reality system. This new system can provide both real-time force feedback and real-time visual feedback during nanomanipulation. We have shown that nano-imprinting and manipulation of nano-particles and nano-rods can be easily performed under assistance of the augmented reality system. In this research, the systems ability is extended to manipulation of DNA molecules. Using a polynomial fitting method, the deformation of DNA molecules is displayed in real time in the augmented reality system during manipulation. Indeed, DNA molecules adopt many different structures including kinks, bends, bulges and distortions. These different structures and inappropriate physical contacts may result in the controversy of DNA conductivity reported over the last decade. The AFM based nanomanipulation system can be used either as a nanolithography tool to make small gap electrodes or a nanomanipulation tool to elongate, deform and cut DNA molecules. The measurement of the conductivity of DNA molecules in their different shapes and structures is a promising method to find conclusive evidences, which verify the electrical conductivity of DNA molecules.

Automated nano-assembly of nanoscale structures

Nanoscale products have many potential applications. The complexity of nanomanufacturing requires to position, manipulate and assemble nanoobjects to form asymmetric patterns. The atomic force microscopy has been proven to be a powerful technique for nanomanufacturing. Typical manual nanomanipulation using an atomic force microscope (AFM) is time-consuming and inefficient. Automated AFM tip path planning is desirable for nanomanufacturing, but does not receive much attention. In this paper, a CAD-guided automated nanomanufacturing system is developed to manufacture a nanostructure/nanodevice based on the CAD model of the nanostructure/nanodevice. The system is implemented to manipulate nanoobjects to manufacture nanostructures automatically.

CAD-guided manufacturing of nanostructures using nanoparticles

The development of nanomanufacturing technologies will lead to potential breakthroughs in manufacturing of new industrial products. Nanomanufacturing by manipulating nanoparticles using an atomic force microscope is desirable to manufacture asymmetric nanodevices and nanostructures. The complexity of nanomanufacturing requires positioning, manipulating and assembling nanoparticles. Typical manual nanomanipulation is time-consuming and inefficient. Automated path planning is desirable for nanomanufacturing, but does not receive much attention. In this paper, a general framework is developed to manufacture nanostructures and nanodevices. An automated tool path planning algorithm is presented. Simulations are performed to test the generated paths. The generated paths are also implemented to manipulate nanoparticles to manufacture nanostructures automatically. The simulation and experimental results are consistent. The general framework can also be extended to manipulate other nanoobjects.

Experimental studies of DNA electrical properties using AFM based nano-manipulator

DNA molecules adopt many different structures including kinks, bends, bulges and distortions. The different structures and inappropriate physical contacts may result in the controversy of DNA conductivity reported over the last decade. In order to prove this hypothesis, an AFM based experimental method has been developed in this paper. The AFM based nanomanipulation system can be used either as a nanolithography tool to make small-gap electrodes or a nanomanipulation tool to elongate, deform and cut DNA molecules. By measuring the conductivity of DNA molecules in different shapes, it is promising to find conclusive evidences to verify the electrical conductivity of DNA molecules.

Augmented reality enhanced "top-down" nano-manufacturing

Assembly of nano-structures involves manipulation of nanoparticles, nano-rods, nanowires and nanotubes. Modelling the behavior of a nano-rod or a nanotube pushed by an AFM tip is much more complex than that of a nano-particle because in the case of the nano-particle usually only translation occurs while for the nano-rod and nanotube both translational and rotational motion occurs during manipulation. In this paper, the behavior of nano-rods under pushing is theoretically analyzed and the real-time interactive forces are used to update the AFM image. The real-time visual display combined with the real-time force feedback provides an augmented reality environment in which the operator not only can feel the interaction forces but can also observe the real-time changes of the nano-environment. The new developed augmented reality system capable of manipulating not only nanoparticles but also nano-rods makes nano-assembly using AFM based nanomanipulation system feasible and applicable.