Tuning the effective coupling of an AFM lever to a thermal bath

Fabrication of Nano-Electro-Mechanical-Systems (NEMS) of high quality is nowadays extremely efficient. These NEMS will be used as sensors and actuators in integrated systems. Their use however raises questions about their interface (actuation, detection, read out) with external detection and control systems. Their operation implies many fundamental questions related to single particle effects such as Coulomb blockade, light matter interactions such as radiation pressure, thermal effects, Casimir forces and the coupling of nanosystems to external world (thermal fluctuations, back action effect). Here we specifically present how the damping of an oscillating cantilever can be tuned in two radically different ways: i) through an electro-mechanical coupling in the presence of a strong Johnson noise, ii) through an external feedback control of thermal fluctuations which is the cold damping closely related to Maxwell's demon. This shows how the interplay between MEMS or NEMS external control and their coupling to a thermal bath can lead to a wealth of effects that are nowadays extensively studied in different areas

Proximity effect on hydrodynamic interaction between a sphere and a plane measured by Force Feedback Microscopy at different frequencies

In this article, we measure the viscous damping $G'',$ and the associated stiffness $G',$ of a liquid flow in sphere-plane geometry in a large frequency range. In this regime, the lubrication approximation is expected to dominate. We first measure the static force applied to the tip. This is made possible thanks to a force feedback method. Adding a sub-nanometer oscillation of the tip, we obtain the dynamic part of the interaction with solely the knowledge of the lever properties in the experimental context using a linear transformation of the amplitude and phase change. Using a Force Feedback Microscope (FFM)we are then able to measure simultaneously the static force, the stiffness and the dissipative part of the interaction in a broad frequency range using a single AFM probe. Similar measurements have been performed by the Surface Force Apparatus with a probe radius hundred times bigger. In this context the FFM can be called nano-SFA

Spectroscopic investigation of local mechanical impedance of living cells

The mechanical properties of PC12 living cells have been studied at the nanoscale with a Force Feedback Microscope using two experimental approaches. Firstly, the local mechanical impedance of the cell membrane has been mapped simultaneously to the cell morphology at constant force. As the force of the interaction is gradually increased, we observed the appearance of the sub-membrane cytoskeleton. We shall compare the results obtained with this method with the measurement of other existing techniques. Secondly, a spectroscopic investigation has been performed varying the indentation of the tip in the cell membrane and consequently the force applied on it. In contrast with conventional dynamic atomic force microscopy techniques, here the small oscillation amplitude of the tip is not necessarily imposed at the cantilever first eigenmode. This allows the user to arbitrarily choose the excitation frequency in developing spectroscopic AFM techniques. The mechanical response of the PC12 cell membrane is found to be frequency dependent in the 1 kHz - 10 kHz range. The damping coefficient is reproducibly observed to decrease when the excitation frequency is increased.Comment: 8 pages, 8 figure

Atomic Force Microscope Functionality Simulation : Physical and Energetic Analogies

Poster - http://www.asmeconferences.org/conference-home/NANO.cfmInternational audienceUsing Atomic Force Microscopes (AFM) to manipulate nano-objects is an actual challenge for both physicians and biologists. Many visual and haptic interfaces between the AFM and experimentalists have already been implemented. The multi-sensory renderings (seeing, hearing, feeling) studied from a cognitive point of view increase the efficiency of the actual interfaces and represent our challenge. To allow the experimentalist to feel and touch the nano-world, we add mixed realities between an AFM and a force feedback device, enriching thus the direct connection by a modeling engine. The functionality of an AFM is described in this paper through physical and energetic analogies

Multi-Sensorial Interface for 3D Teleoperation at Micro and Nanoscale

International audienceThis paper presents the design of a new tool for 3D manipulations at micro and nanoscale based on the coupling between a high performance haptic system (the ERGOS system) and two Atomic Force Microscope (AFM) probes mounted on quartz tuning fork resonators, acting as a nano tweezers. This unique combination provides new characteristics and possibilities for the localization and manipulation of (sub)micronic objects in 3 dimensions. The nano robot is controlled through a dual sensorial interface including 3D haptic and visual rendering, it is capable of performing a number of real-time tasks on different samples in order to analyse their dynamic effects when interacting with the AFM tips. The goal is then to be able to compare mechanical properties of different matters (stiffness of soft or hard matter) and to handle submicronic objects in 3 dimensions

Approaching nano-spaces : 1-DOF nanomanipulator

International audienceDifferent scientific fields like biology or physics develop applications where a successful nano-object manipulation is peremptory. In the aim of realizing a useful multi-sensory interface allowing thus, human presence in the nano-world, we present in this paper the first results from the one-degree of freedom (DOF) nano-manipulator developments that connects an Atomic Force Microscope (AFM) with our Force Feedback Gestural Device (FFGD). The application of the AFM-FFGD coupling contains a redefining of the real-time remote-control handling, bringing in the concept of mixed reality. The designed models described in this paper represent the basis of the virtual reconstruction of a nano-scene

Touching nanospace : Atomic Force Microscope coupling with a force feedback manipulation system

International audienceToday, Scanning Probe Microscopies (SPM) are widely used in physics, chemistry and biology in order to image surfaces with a great resolution but also more and more as tool to manipulate nano-objects or to modify surfaces at nanometer scale. At the present time, using SPM to manipulate nano-objects is not user friendly and is time consuming. These two weak points are due to the absence of feedback control in real time of the tip movements and of tip-surface or tip/nano-objects interactions. The aim of our research work is to realise an active feedback control interface which will allow to feel in real time but also to simulate the tip movement and/or tip-surface/nano-objects interactions

Giant slip lengths of a simple fluid at vibrating solid interfaces

It has been shown recently [PRL 102, 254503 (2009)] that in the plane-plane configuration a mechanical resonator vibrating close to a rigid wall in a simple fluid can be overdamped to a frozen regime. Here, by solving analytically the Navier Stokes equations with partial slip boundary conditions at the solid fluid interface, we develop a theoretical approach justifying and extending these earlier findings. We show in particular that in the perfect slip regime the above mentioned results are, in the plane-plane configuration, very general and robust with respect to lever geometry considerations. We compare the results with those obtained previously for the sphere moving perpendicularly and close to a plane in a simple fluid and discuss in more details the differences concerning the dependence of the friction forces with the gap distance separating the moving object (i.e., plane or sphere) from the fixed plane. Finally, we show that the submicron fluidic effect reported in the reference above, and discussed further in the present work, can have dramatic implications in the design of nano-electromechanical systems (NEMS).Comment: submitted to PRE (see also PRL 102, 254503 (2009)