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. Note to Practitioners-Almost all the existing AFM only has one single tip as the end-effector, thus during nanomanipulation, the interaction force between the object and the tip can only be applied through a single point. This often leads the AFM tip to slip over or slip away from the object, and makes it difficult to realize a posture constant manipulation during nanorod manipulation. All of these hinder the efficiency and effectiveness of manipulation based on AFM. In order to solve the problems, a new strategy for tip-based manipulation named nano-hand is proposed. In this approach, a set of positions are first predefined based on the kinematics model of the object. The AFM tip is then moved to these positions to generate a short pushing action to the target object in a relatively high frequency to mimic multi-fingered hand with single AFM tip. Finally, a robotic caging at nanoscale is formed. In this way, the problems caused by a sharp single tip manipulation can be solved into a certain extent. The simulation and experimental results show a stable and controllable nanomanipulation can be obtained through the developed nano-hand strategy.