Ning Xi

Design, Fabrication, and Visual Servo Control of an XY Parallel Micromanipulator With Piezo-Actuation

This paper presents a complete design and development procedure of a new XY micromanipulator for two-dimensional (2-D) micromanipulation applications. The manipulator possesses both a nearly decoupled motion and a simple structure, which is featured with parallel-kinematic architecture, flexure hinge-based joints, and piezoelectric actuation. Based on pseudo-rigid-body (PRB) simplification approach, the mathematical models predicting kinematics, statics, and dynamics of the XY stage have been obtained, which are verified by the finite-element analysis (FEA) and then integrated into dimension optimization via the particle swarm optimization (PSO) method. Moreover, a prototype of the micromanipulator is fabricated and calibrated using a microscope vision system, and visual servo control employing a modified PD controller is implemented for the accuracy improvement. The experiments discover that a workspace size of 260 mum times 260 mum with a 2-D positioning accuracy and repeatability around 0.73 and 1.02 mum, respectively, can be achieved by the micromanipulator.

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.

AFM-Based Robotic Nano-Hand for Stable Manipulation at Nanoscale

One of the major limitations for Atomic Force Microscopy (AFM)-based nanomanipulation is that AFM only has one sharp tip as the end-effector, and can only apply a point force to the nanoobject, which makes it extremely difficult to achieve a stable manipulation. For example, the AFM tip tends to slip-away during nanoparticle manipulation due to its small touch area, and there is no available strategy to manipulate a nanorod in a constant posture with a single tip since the applied point force can make the nanorod rotate more easily. In this paper, a robotic nano-hand method is proposed to solve these problems. The basic idea is using a single tip to mimic the manipulation effect that multi-AFM tip can achieve through the planned high speed sequential tip pushing. The theoretical behavior models of nanoparticle and nanorod are developed, based on which the moving speed and trajectory of the AFM tip are planned artfully to form a nano-hand. In this way, the slip-away problem during nanoparticle manipulation can be get rid of efficiently, and a posture constant manipulation for nanorod can be achieved. The simulation and experimental results demonstrate the effectiveness and advantages of the proposed method.

Force Analysis of Top-Down Forming CNT Electrical Connection Using Nanomanipulation Robot

Carbon nanotube (CNT) is an ideal candidate for future nanoelectronics because of its small diameter, high current-carrying capability, and high conductance in a one-dimensional nanoscale channel. The most challenging part in fabricating nanosystems could be the formation of CNT connections. Existing techniques in forming CNT connections are suffered from problems in forming a single CNT connection or not being able to precisely deposit CNTs on specific locations. One of the efficient and reliable ways to form CNT connections is to make connections between CNTs and beforehand-fabricated electrodes by using an atomic force microscopy based nanomanipulation robot, which has the ability to manipulate single CNT with nanometre precision in a controllable manner. But even this, it often happens that CNT cannot be manipulated onto the top surface of electrodes, because there are some restrict conditions among electrode thickness, CNT radius and attitude of AFM tip, this paper study this problem in detail, some experimental results are also presented

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.

Scan range adaptive hysteresis/creep hybrid compensator for AFM based nanomanipulations

Atomic force microscopy (AFM) based nanomanipulations have been successfully applied to various fields such as physics, material science and biomedical studies. In general, the precision of AFM based nanomanipulation has been compromised mainly by hysteresis and creep of the piezo actuator. In this paper, a new approach, named scan range adaptive hysteresis/creep hybrid (SAH) compensator, is proposed to compensate the nonlinear rate-independent hysteresis and linear rate-dependent creep effects of the open-loop AFM based manipulation system. The nonlinear portion of the SAH compensator consists of Prandtl-Ishlinskii (PI) play operators and the linear portion, which serves as an input amplifier, consists of creep operators. The advantage of the SAH compensator is that the hysteresis compensator portion can optimize its parameters to adapt to the manipulation range, which guarantees the same level of relative positioning accuracy in different operation scales. This SAH compensator is easy to implement in a range of scanning probe microscopies (SPMs). Experimental results show that the SAH compensator can compensate hysteresis and creep with higher accuracy than the conventional creep/hysteresis hybrid compensator in different operation scales.

Non-vector space stochastic control for nano robotic manipulations.

In this paper, we present a non-vector space stochastic control method for nano robotic manipulations. Non-vector space control employs sets as the states and formulates dynamics equations in the space of sets. This method provides a natural description of physical phenomena such as images. When applied to nanomanipulations, it excludes the use of external position sensors, and the positioning precision can be as good as the imaging resolution. In this paper, we investigate the stochastic control problem for non-vector space dynamic systems when the sets are corrupted by random noises. We use Kalman filtering to estimate the true set for feedback control. The stability of the method is investigated. We apply the method to atomic force microscope (AFM) system to improve position accuracies of nanomanipulations. Simulation and experimental results have clearly validated the proposed method.

Real-time position error detecting in nanomanipulation using Kalman filter

The main roadblock to atomic force microscope (AFM) based nanomanipulation is lack of real time visual feedback. Although the model based visual feedback can partly solve this problem, due to the complication of nano environment, it is difficult to accurately describe the behavior of nano-objects with a model. The modeling error will lead to an inaccurate feedback and a failed manipulation. In this paper, a Kalman filter is developed to real time detect this modeling error. During manipulation, the residual between the estimated behavior and the visual display behavior is real time updated. The residuals Mahalanobis distance is calculated and compared with an threshold to determine whether there is a position error. Once the threshold is exceeded, an alarm signal will be triggered to tell the system there is a position error. Furthermore, the position error can be on-line corrected by local scan method. With the assistance of Kalman filter and local scan, the position error not only can be real-time detected, but also can be online corrected. The visual display keeps matching with the real manipulation result during the whole manipulation process, which significantly improve the efficiency of the AFM based nano-assembly. Experiments of manipulating nano-particles are presented to verify the effectiveness of Kalman filter and local scan method.