Sharp Pt/Ir tips have been reproducibly etched by an electrochemical process using an inverse geo... more Sharp Pt/Ir tips have been reproducibly etched by an electrochemical process using an inverse geometry of an electrochemical cell and a dedicated electronic device which allows us to control the applied voltages waveform and the intensity of the etching current. Conductive tips with a radius smaller than 10 nm were routinely produced as shown by field emission measurements through FowlereNordheim plots. These etched tips were then fixed on a quartz tuning fork force sensor working in a qPlus configuration to check their performances for both scanning tunneling microscopy (STM) and atomic force microscopy (AFM) imaging. Their sharpness and conductivity are evidenced by the resolution achieved in STM and AFM images obtained of epitaxial graphene on 6HeSiC(0001) surface. The structure of an epitaxial graphene layer thermally grown on the 6HeSiC(0001) ð6 ffiffiffi 3 p  6 ffiffiffi 3 p Þ R30 reconstructed surface, was successfully imaged at room temperature with STM, dynamic STM and by frequency modulated AFM.
2010 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2010
This study proposes a tuning fork probe based nanomanipulation robotic system for mechanical char... more This study proposes a tuning fork probe based nanomanipulation robotic system for mechanical characterization of ultraflexible nanostructures under scanning electron microscope. The force gradient is measured via the frequency modulation of a quartz tuning fork and two nanomanipulators are used for manipulation of the nanostructures. Two techniques are proposed for attaching the nanostructure to the tip of the tuning fork probe. The first technique involves gluing the nanostructure for full range characterization whereas the second technique uses van der Waals and electrostatic forces in order to avoid destroying the nanostructure. Helical nanobelts (HNB) are proposed for the demonstration of the setup. The nonlinear stiffness behavior of HNBs during their full range tensile studies is clearly revealed for the first time. Using the first technique, this was between 0.009 N/m for rest position and 0.297 N/m before breaking of the HNB with a resolution of 0.0031 N/m. For the second experiment, this was between 0.014 N/m for rest position and 0.378 N/m before detaching of the HNB with a resolution of 0.0006 N/m. This shows the wide range sensing of the system for potential applications in mechanical property characterization of ultraflexible nanostructures.
The invention relates to a method of manufacturing a biosensor. The biosensor of the invention co... more The invention relates to a method of manufacturing a biosensor. The biosensor of the invention comprises a microbeam, which is the mobile part of the biosensor, linked to a support, at least one electrode, at least part of which is embedded in the microbeam, at least one biological molecule A grafted onto the microbeam in a different zone from the zone wherein the at least one electrode is embedded, and a mechanoelectrical transducer for converting variations of the mechanical properties of the microbeam into an electrical signal, when the biological molecule A is placed in contact with a biological molecule B to be detected and/or quantified. The method of the invention is characterized in that the microbeam and its support are made of a fluoropolymer material and form an integral component, and in that it comprises the following steps: a) formation of at least one electrode on fluoropolymer material sheet, b) optionally formation of a ferromagnetic material pad on the electrode(s)...
The present invention discloses a micromechanical measurement system comprising: - a laser source... more The present invention discloses a micromechanical measurement system comprising: - a laser source (1), for emitting a coherent light beam (2), - an interferometer, - a camera (10), for acquiring a picture of the interferogram composed of a plurality of fringes, - image processing means. The image processing means are arranged in order to compute the absolute deflection z x of the movable area at a position x along the length of the flexible micromechanical structure by performing one initialization in a first interferogram picture taken at a fixed time to and at least one measurement in a second interferogram picture taken at a variable time t.
A probe arrangement with a probe for local electrophysiological analysis of cells (4) such as pat... more A probe arrangement with a probe for local electrophysiological analysis of cells (4) such as patch-clamp techniques for use with atomic force microscopy, has a probe with a cantilever arm (2) connected to a probe holder (3). The probe has a probe tip (4) at a probing end (5) of the cantilever arm (2) and a fluid channel (6) in the cantilever arm (2) connecting a probe tip aperture (7) with a fluid reservoir (8) via a duct (9). The fluid channel (6), the duct (9) and the fluid reservoir (8) are adapted to be filled with a fluid solution (10) enabling ion transport for electrophysiological analysis. A first electrode (15) for electrophysiological analysis is placed in the fluid reservoir (8) and/or in the duct (9) and/or in the fluid channel (6).
Piezoresistive scanning probe arrays have been developed in view of operation in liquid environme... more Piezoresistive scanning probe arrays have been developed in view of operation in liquid environments. When the cantilevers are immersed in electrically conductive solutions like for instance physiological buffers, the piezoresistive sensing elements as well as the metal connections have to be passivated. For that purpose, the sensors and the metal wiring were covered with different protective coatings. Long term stability of these passivation layers was demonstrated by imaging in a buffer solution for several hours. Moreover, in view of reducing the damping and thus decreasing the hydrodynamic resistance in liquids, special truss cantilevers have been developed. It was found that this special design conferred no improvement in terms of Q-factor and resonant frequency when operated in water. In order to explain the behaviour of these probes, a theoretical model was established. The model predicted that truss structures could theoretically improve the cantilever performances in liquid, but the probes would need to be operated at high frequency, above 10MHz.
2013 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2013
Typical methods of measuring mechanical properties at the micro-scale are destructive, and do not... more Typical methods of measuring mechanical properties at the micro-scale are destructive, and do not allow proper characterisation on resonant MEMS/NEMS. In this paper, a cartography of local stiffness variations on a suspended micromembrane is established for the first time, by a tuning-forkbased dynamic force sensor inside a SEM. Experiments are conducted on InP membranes 200nm thin, using a 9-DoF nanomanipulation system, complemented with virtual reality and automation tools. Results provide stiffness values ranging from 0.6 to 3 N/m on a single sample.
Nowadays tools based on Scanning Probe Methods (SPM) have become indispensable in a wide range of... more Nowadays tools based on Scanning Probe Methods (SPM) have become indispensable in a wide range of applications such as cell imaging and spectroscopy, profilometry, or surface patterning on a nanometric scale. Common to all SPM techniques is a typically slow working speed which is one of their main drawbacks. The SPM speed barrier can be improved by operating a number of probes in parallel mode.
Les techniques d'analyse basées sur la microscopie à force atomique (AFM) pour les mesures de for... more Les techniques d'analyse basées sur la microscopie à force atomique (AFM) pour les mesures de forces locales en milieu physiologique ouvrent de nouvelles opportunités de caractérisation pour la nano-médecine et le diagnostic personnalisé. Les nano-capteurs de force détectant des interactions moléculaires spécifiques ligandprotéine peuvent être utilisés pour l'ingénierie pharmaceutique ou la détection de bio-marqueurs. Ces mesures de force spécifiques permettent de mieux comprendre les mécanismes de déstabilisation des protéines dans certaines pathologies, et par quels mécanismes certaines molécules se lient entre elles et modulent les récepteurs transmembranaires des cellules. En parallèle, la cartographie AFM a déjà démontré sa capacité d'imagerie de haute résolution de structures périodiques de protéines, ou de protéines isolées, sans aucun équivalent instrumental. Aujourd'hui, les nano-capteurs à détection intégrée augurent d'une nouvelle génération de microscopes à force atomique repoussant les limites actuelles.
ABSTRACT A tuning fork AFM (atomic force microscope) scanning probe has been used to study the ch... more ABSTRACT A tuning fork AFM (atomic force microscope) scanning probe has been used to study the chemical grafting between a functionalized tip and BSA (bovine serum albumin) protein. A non-conventional chemistry based on diazonium salts has been applied to control the hydrophobicity and hydrophilicity of the tip termination, and to graft proteins on surface. Unfolding signatures during the protein stretching have been observed, using amplitude modulation (AM-AFM) control of the probe. We propose a methodology to obtain quantitative information of the withdrawal forces from the amplitude and phase signals. Our results demonstrate the great potential of this new piezoelectric probe combined in term of sensitivity and versatility of the chemical functionalization of the tip to analyze biological materials.
Atomic force microscopy (AFM) has been widely used in biotechnological research to visualize prot... more Atomic force microscopy (AFM) has been widely used in biotechnological research to visualize proteins or cell components with a sub-nanometric resolution. Most of the commercial AFM systems use the standard optical lever method of detection. However, the optical beam deflection technique integrated in AFM presents some disadvantages such as the thermal drift due to cantilever elongation and bending caused by the heat dissipation of the laser diode. Also, optical artifacts and interferences are usually observed in liquid environment with the optical detection, and the laser beam alignment procedure can be an elaborate process in liquid environment. Thus, it is extremely interesting to find an alternative approach to resolve such type of problems. Herein, we introduce a self-sensing piezoelectric tuning fork atomic force microscope (AFM) for molecular imaging on individual proteins. AFM measurements were performed on antibodies samples (IgG and IgM) to study the stability and applicability of this sensor for investigation of soft materials with high dynamical tendency. In this work, we could characterize the substructure of isolated IgG and IgM antibodies adsorbed onto mica surface in air with high resolution imaging. Moreover, we have identified clearly different conformations and substructure differences of individual antibodies with AFM operating in Amplitude Modulation (AM-AFM) and Phase Modulation (PM-AFM) imaging. The used methodology revealed to be very promising approach for high resolution imaging of isolated proteins with well-defined structures.
This study proposes a tuning fork probe based nanomanipulation robotic system for mechanical char... more This study proposes a tuning fork probe based nanomanipulation robotic system for mechanical characterization of ultraflexible nanostructures under scanning electron microscope. The force gradient is measured via the frequency modulation of a quartz tuning fork and two nanomanipulators are used for manipulation of the nanostructures. Two techniques are proposed for attaching the nanostructure to the tip of the tuning fork probe. The first technique involves gluing the nanostructure for full range characterization whereas the second technique uses van der Waals and electrostatic forces in order to avoid destroying the nanostructure. Helical nanobelts (HNB) are proposed for the demonstration of the setup. The nonlinear stiffness behavior of HNBs during their full range tensile studies is clearly revealed for the first time. Using the first technique, this was between 0.009 N/m for rest position and 0.297 N/m before breaking of the HNB with a resolution of 0.0031 N/m. For the second experiment, this was between 0.014 N/m for rest position and 0.378 N/m before detaching of the HNB with a resolution of 0.0006 N/m. This shows the wide range sensing of the system for potential applications in mechanical property characterization of ultraflexible nanostructures.
Cell adhesion to surfaces represents the basis for niche colonization and survival. Here we estab... more Cell adhesion to surfaces represents the basis for niche colonization and survival. Here we establish serial quantification of adhesion forces of different cell types using a single probe. The pace of single-cell force-spectroscopy was accelerated to up to 200 yeast and 20 mammalian cells per probe when replacing the conventional cell trapping cantilever chemistry of atomic force microscopy by underpressure immobilization with fluidic force microscopy (FluidFM). In consequence, statistically relevant data could be recorded in a rapid manner, the spectrum of examinable cells was enlarged, and the cell physiology preserved until approached for force spectroscopy. Adhesion forces of Candida albicans increased from below 4 up to 16 nN at 37uC on hydrophobic surfaces, whereas a Dhgc1-mutant showed forces consistently below 4 nN. Monitoring adhesion of mammalian cells revealed mean adhesion forces of 600 nN of HeLa cells on fibronectin and were one order of magnitude higher than those observed for HEK cells.
ABSTRACT We present the results of the multiscale modeling of the process of lateral manipulation... more ABSTRACT We present the results of the multiscale modeling of the process of lateral manipulation of a Pd adatom adsorbed on the MgO (001) surface using a noncontact atomic force microscope (AFM) at finite temperature and in real time as a tip moves above the surface. We show that the stochastic motion of Pd adatoms can be controlled by localized forces from an oscillating tip and demonstrate how this can be achieved in practice. The energy barriers for manipulation as a function of tip position in three dimensions above the surface are determined from atomistic calculations and then used in a kinetic Monte Carlo algorithm to determine the evolution of the system at a finite temperature and in real time for a realistic trajectory of the tip, which is in turn governed by a complete numerical simulation of the instrument including the response of the feedback loops. We can then predict the probability of a successful manipulation event for a given procedure. The multiscale modeling technique developed in this work can be used to determine optimum experimental protocols for controlled single-atom manipulation using noncontact AFM.
Physica E: Low-dimensional Systems and Nanostructures, 2003
We present a theoretical and experimental study of oxide-conÿned top-emitting VCSELs used as reso... more We present a theoretical and experimental study of oxide-conÿned top-emitting VCSELs used as resonant detectors. Oxide-mode in uence on the detection spectrum is discussed. ?
Using a virtual dynamic atomic force microscope, that explicitly simulates the operation of a non... more Using a virtual dynamic atomic force microscope, that explicitly simulates the operation of a non-contact AFM experiment, we have performed calculations to investigate the formation of atomic-scale contrast in dissipation images. A non-conservative tip-surface interaction was implemented using the theory of dynamical response in scanning probe microscopy with energies and barriers derived from realistic atomistic modelling. It is shown how contrast in the damping signal is due to the hysteresis in the tip-surface force and not an artefact of the finite response of the complicated instrumentation. Topography and dissipation images of the CaO(001) surface are produced which show atomic-scale contrast in the dissipation with a corrugation of approximately 0.1 eV, which is typical of that observed in images of similar binary ionic surfaces. The effect of the fast-direction scanning speed on the image formation is also investigated and discussed.
We present the results of calculations performed to investigate the process of single-atom manipu... more We present the results of calculations performed to investigate the process of single-atom manipulation with the non-contact atomic force microscope comparing the two most common experimental set-ups: a conventional large amplitude silicon cantilever and a small amplitude quartz tuning fork. The manipulation of a model system---an oxygen vacancy in the MgO(001) surface by a single vertical approach at a fixed lateral position---is simulated for each set-up using a detailed and realistic atomistic model that accounts for temperature and the tip trajectory, and it is found that both approaches produce the manipulation event in approximately the same way. The behaviour of the tip dynamics and the resulting response of the instrumentation to the manipulation event is studied using a virtual dynamic atomic force microscope that includes a realistic description of noise for each type of set-up. The results of these calculations indicate how a single-atom manipulation can be performed and recognized by each type of experiment.
A precise experimental investigation of the amplitude and phase resonance curves of a driven dyna... more A precise experimental investigation of the amplitude and phase resonance curves of a driven dynamic force microscope (DFM) cantilever interacting with an Al 2 O 3 (0001) surface in ultra-high vacuum is reported. The large amplitude (a few tens of nanometres), high cantilever stiffness (25 N m −1 ) and high quality factor (a few 10 4 ) characterizing these experiments are typical of the frequency modulation (FM) mode of DFM. The whole range of tip-substrate distances where a stationary oscillation of the cantilever can be maintained is explored. It covers two different regimes: a large distance regime where only long range conservative van der Waals interactions contribute and a small distance regime where short range interactions play a significant role. A comparison is made with frequency shift and excitation amplitude curves as a function of the distance acquired in the FM mode. It is also shown that approach-retract amplitude and phase curves usually obtained in the amplitude modulation mode can be extracted from these data. These experimental results are compared with analytical predictions reported in the literature. An excellent agreement is found in the van der Waals domain, allowing us to evaluate the Hamaker constant for the alumina-vacuum-silicon system.
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Papers by Jerome Polesel