Nano Forces Research Articles

Exploring magneto-electric nanoparticles (MENPs): a platform for implanted deep brain stimulation

Exploring magneto-electric nanoparticles (MENPs): a platform for implanted deep brain stimulation

Aspect ratio and dimension effects on nanorod manipulation by atomic force microscope

This Letter deals with modelling of nanorod manipulation using an atomic force microscope (AFM). Widespread application of nanorods and a lack of real-time imaging in nanotechnology make process modeling necessary. This model considers three basic nano forces: van der Waals, friction and adhesive contact force for a quantitative analysis of effective parameters. A dynamic analysis of nanorod pushing considering depression on an elastic substrate, indention between tip-nanorod and deflection along a straight path is presented. Incorporating a beam on the elastic substrate assumption, a complete model for nanorod manipulation is introduced. The model is verified using available (theoretical and experimental) results. A polystyrene nanorod is simulated and critical force and time, maximum deflection and safety factor are obtained. Aspect ratio and dimension effects are the most significant contributions of this work. Also, it is determined that the dynamic modes of micro- and nanorods are different. Despite rolling being a dominant mode in microrod manipulation, sliding is observed in nanorod pushing as the dominant dynamic mode. Results show that an increase in length causes considerable deflection and decrease in the safety factor.

Facility and methods for the measurement of micro and nano forces in the range below 10−5 N with a resolution of 10−12 N (development concept)

This contribution describes the concept of a new high precision micro- and nano-force measurement facility. It consists of a measuring disc-pendulum and an identical reference disc-pendulum for the reduction of thermal and seismic noise. According to the theoretical calculations in the paper, the disc-pendulums with electrostatic stiffness reduction and electrostatic deflection compensation should allow quasi-static forces to be measured in the range <10−5 N with a force resolution of 10−12 N.

Implementation of self-sensing SPM cantilevers for nano-force measurement in microrobotics

Micromanipulation tasks have to be solved in the assembly of microsystems, the handling of biological cells and the handling of specimens for scanning electron microscopy. For these applications, we have developed a flexible micromanipulation station, including direct-driven robots a few cubic centimeters small. The robots are able to perform high-precise manipulation and positioning of microobjects. Force-controlled microgripping strategies are now necessary to develop robust microassembly strategies. Microgripping is different from conventional gripping in two ways. First, microparts with dimensions less than 100 μm are often fragile and can easily be damaged during gripping, thus special grasping techniques are needed. Second, the mechanics of manipulation in the microworld are much different than in the macro-world. Part interactions in the microworld are dominated by adhesive forces making it difficult to release parts during manipulation tasks. Several microgrippers that do not employ force feedback have been developed; force-controlled microgrippers are much less common. Grippers with integrated piezoresistive force sensors and with attached strain gauges have been reported. These approaches, however, are limited in their ability to resolve the gripping force. Hence, we are currently integrating self-sensing SPM cantilevers into a gripper of our microrobots. These cantilevers operate by measuring stress-induced electrical resistance changes in an implanted conductive channel in the flexure legs of the cantilever. The real-time force feedback provided by these sensors enables us to better understand the prevailing nano forces and dynamics, what is indispensable for reliable micromanipulation strategies.

Tele-nanorobotics using an atomic force microscope as a nanorobot and sensor

In this paper, a tele-nanorobotic system using an atomic force microscope (AFM) as the nanorobot and sensor has been proposed. Modeling and control of the AFM cantilever, and modeling of nanometer scale forces have been realized for telemanipulation applications. In addition to three-dimensional virtual reality visual feedback in the user interface, a 1 d.o.f. haptic device has been constructed for nano-scale haptic sensing. For feeling the nano forces, a bilateral teleoperation control system with virtual impedance approach has been introduced. Initial experiments and simulations on the AFM and teleoperation system show that the system can be utilized for different telenanomanipulation applications such as two-dimensional nano particle assembly or biological object manipulation.