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Nanomanipulation and nanocharacterisation with atomic force microscope and haptic force feedback

Contact : André Preumont

Motivation

Nanotechnology tries to develop new kind of materials and tools to increase the performance of sensors, actuators, computers,… One of the biggest challenges of this technology is the manipulation of components with dimensions less than 100 nm and subjected to forces at molecular level like Van der Waals, electrostatic, capillary and chemical forces.

A lot of applications can be found in several fields like biotechnologies (ADN and protein study), data storage or material science ( nanotube or surface film characterization).

Principle

One way to achieve nanomanipulation is the use of a surface imaging tool called AFM (Atomic Force Microscope). The main structure of an AFM nanomanipulator is shown in Fig.1. The nanometric objects are manipulated by the AFM’s cantilever with a feedback loop on the exerted force. The displacements are done by piezoelectric actuators and the interaction forces are measured through the deflection of the cantilever.

Fig. 1: Main structure of an AFM nanomanipulator

As the dimensions are bellow the micrometer, it is impossible for an operator to observe his manipulation through an optical microscope. To achieve an effective work, an other kind of interface between the user and the nanoworld is necessary. In a teleoperated manipulation, it is composed of a 3D graphic virtual reality and a haptic device. This last device exerts scaled forces from the AFM measurement to the operator and sends the scaled position from the hand of the user to the microscope tip (Fig. 2). This setup can improve drastically the controllability and efficiency of nanomanipulations.

Fig. 2: Teleoperated manipulator

In our Laboratory, we use an AFM SMENA A from NT-MDT as nanomanipulator.

On the other side, we use two kinds of haptic device. First we have developed a 3 DOF haptic device with voice-coil actuators and potentiometer sensors (Fig. 3). Second, we use a 3 DOF desktop Phantom haptic. The two main parts of this hardware are linked by high performance microcontrollers and a modular real-time program in the MATLAB environment.

Fig. 3: 3 DOF haptic device

Results

Until now, with our system, we realized manual mechanical lithography in CD sample (Fig. 4) and we succeed to sense surface topography and surface forces (like capillary) through the haptic device.

At this time, our research activities are involved in the following problems:

  • improve transparency of the force reflection from the AFM.
  • Study the real interaction (theoretically and experimentally) between the probe and the samples.
  • Improve force measurement capabilities of the probe.

Fig. 4: Manual mechanical lithography in CD sample

Related publications

  • P.Letier, T. Saive, I. Burda, Interface Haptique pour Nanomanipulateur AFM. 6th National Congress on Theoretical and Applied Mechanics, Ghent May 2003. (pdf)