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International audience; Manipulating micro-objects plays a crucial role in a wide range of fundamental and applied research works. Here, we propose an original strategy based on the chemical modification of a substrate by hydrogen-bonded films elaborated by layer-by-layer (LbL) assemblies of poly(ethylene glycol) (PEG) and poly(acrylic acid) (PAA). First, the influence of the polymer molecular weight on the growth of the PEG/PAA multilayer was evaluated. Optical reflectometry analysis used to follow in situ the film buildup revealed a strong dependence of the deposited amount of polymer on the ratio of monomer units of each polymer (nPAA/nPEG). Then, colloidal probe atomic force microscopy (AFM) microscopy was carried out in an aqueous medium to monitor the adhesion forces of multilayer surfaces composed of N polymer layers. Pull-off forces were converted using the Johnson–Kendall–Roberts (JKR) model to access the thermodynamic work of adhesion. Results indicated that PEG/PAA multilayer films exhibit weak adhesion forces that are sensitive to the number of deposited polymer layers at pH 2. In addition, a progressive increase of the solution pH reduced the adhesion due to the destruction of the hydrogen-bonded multilayer film. To simulate the capture and the release of a micro-object, borosilicate particles acting as spherical micro-objects were adsorbed onto a PEG/PAA film. Once again, an increase of the solution pH led to desorption of particles, as shown by optical microscopy. Finally, an AFM tip functionalized by a PEG/PAA multilayer was used to achieve successful micromanipulation operations (capture and release) of a 10 μm diameter borosilicate sphere in an aqueous solution.

A three-dimensional model enables the development of accurate solutions to have more information about the thickness, texture, and characteristics of small-size samples for education and metrology applications. This project proposes an idea to obtain a complete 3D surface reconstruction using the application of Pollen 3D for the scanning electron microscope (SEM) images with high magnification. The main objective is to have a set of images of the complete 360° rotation of the sample with a robot inside the chamber of the SEM. Simulation SEM images with Blender (open source application) are proposed for results validation.

International audience; In this paper, we propose an origami-based auxetic tunable Helmholtz resonator by controlling the volume of the cavity to allow a real-time tunability of the resonance frequency. The design is inspired by the waterbomb origami base, which expands when stretched and contracts when compressed. Such a foldable structure offers a wide range of volume variation, which corresponds to a larger frequency shift in the bandwidth of interest. Based on the design of the origami resonator, multi-physical models are established to understand and predict the parameters' effect on the device's behavior. After fabrication, experimental tests are conducted on physical prototypes to validate the models and illustrate the effectiveness of the concept

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International audience; In many cases, soft and continuum robots represent an interesting alternative to articulated robots because they have the advantages of miniaturization capability, safer interactions with humans and often simpler fabricating and integration. However, these benefits are usually considered to arise at the expense of accuracy and precision because of the soft or flexible limbs. This paper demonstrates that, with a proper design, a planar parallel continuum robot is capable of great precision. Indeed, the proposed 3-Degrees-of-Freedom planar parallel continuum robot exhibits a precision of 9.13 nm in position and 1.2 μrad in orientation. In addition, the novel robotic design leverages the effect of the actuators' defects, making the robot more precise than its own actuators. Finally, the workspace of the proposed robot (62.3 mm2, 0.6452 rad) is significantly larger than most compliant mechanisms, which is particularly interesting when both very high precision and relatively large displacements are required.

International audience; Olfactory dysfunction could be an early and reliable indicator for the diagnosis of neurodegenerative disorders such as Alzheimer and Parkinson's diseases. In this paper, we compare the potential of different noninvasive medical imaging modalities (optical coherence tomography, confocal microscopy, and fluorescence endomicroscopy) to distinguish how the olfactory epithelium, both at the cellular and the structural levels, is altered. Investigations were carried out on three experimental groups: two pathological groups (mice models with deliberately altered olfactory epithelium and Alzheimer's disease transgenic mice models) were compared with healthy mice models. As histological staining, the three tested noninvasive imaging tools demonstrated the general tubular organization of the olfactory epithelium on healthy mice. Contrary to OCT, confocal microscopy, and endomicroscopy allowed visualizing the inner structure of olfactory epithelium as well as its morphological or functional changes on pathological models, alterations classically observed with histological assessment. The results could lead to relevant development of imaging tools for noninvasive and early diagnosis of neurodegenerative diseases through the in situ characterization of the olfactory epithelium.

International audience; In the growing field of origami engineering, self-folding is of a high regard. The latter is regularly used by nature as an efficient approach for autonomous growing and reorganizing. In this work, we present a self-folding approach based on Electro-Active Polymer (EAP), especially Conductive Polymers (CP). This approach proposes lightweight, compact and energy efficient self-folding structures, as well as large angle and reversible folding. We study the behavior of a three-segment milli-structure containing two passive segments made of paper, separated by an active segment made of CP. The folding motion of the structure was modeled and experimentally validated. Furthermore, as a proof of concept, a self-folding origami cube is presented.

International audience; This paper deals with the development of a vision-based controller for a continuum robot architecture. More precisely, the controlled robotic structure is based on three-tube concentric tube robot (CTR), an emerging paradigm to design accurate, miniaturized, and flexible endoscopic robots. This approach has grown considerably in the recent years finding applications in numerous surgical disciplines. In contrast to conventional robotic structures, CTR kinematics arise many challenges for an optimal control such as friction, torsion, shear, and non-linear constitutive behavior. In fact, in order to ensure efficient and reliable control, in addition to computing an analytical and complete kinematic model, it is also important to close the control loop. To do this, we developed an eye-in-hand visual servoing scheme using a millimeter-sized camera embedded at the robot's tip. Both the kinematic model and the visual servoing controller were successfully validated in simulation with ViSP (Visual Servoing Platform) and using an experimental setup. The obtained results showed satisfactory performances for 3-degrees of freedom positioning and path following tasks with adaptive gain control.

Dexterity of robots is highly required when it comes to integration for medical applications. Major efforts have been conducted to increase the dexterity at the distal parts of medical robots. This paper reports on developments toward integrating biocompatible conducting polymers (CP) into inherently dexterous concentric tube robot paradigm. In the form of tri-layer thin structures, CP micro-actuators produce high strains while requiring less than 1 V for actuation. Fabrication, characterization, and first integrations of such micro-actuators are presented. The integration is validated in a preliminary telescopic soft robot prototype with qualitative and quantitative performance assessment of accurate position control for trajectory tracking scenarios. Further, CP micro-actuators are integrated to a laser steering system in a closed-loop control scheme with displacements up to 5 mm. Our first developments aim toward intracorporeal medical robotics, with miniaturized actuators to be embedded into continuum robots.

International audience; "This paper discusses the development of a mosaick- ing algorithm for building large and high resolution confocal images. Due to the nature of optics and vision systems in general, there is still a dilemma between choosing a wide field-of-view (FOV) and high-resolution. The most accepted solution is to opt for a high-resolution optics and expand the FOV algorithmically thanks to mosaicking approaches. The study reported in this paper consists of online and real-time construction of large mosaics using individual confocal images with a micrometer resolution. These individual images are provided by a confocal laser endomicroscopy system which can grab in vivo real-time images through a minimally invasive access. The acquisition of the confocal images is achieved by moving the imaging probe on the studied sample surface with a constant contact between the probe and the sample. The mosaicking algorithm proposed in this paper deals with the combination of both the robot inputs and the image regis- trations. The proposed method has demonstrated very promising performances in terms of accuracy and robustness with regard to image noise (poor image quality or loss of contact between the probe and the sample) as well as misregistration issues. Experiments carried out with a highly accurate robotic system and a ground truth obtained by conventional optical microscopy demonstrate the robustness of the proposed approach. "

In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, or crystals, i.e., silica, silicon, potassium tantalite, or lithium niobate. This method is usually described as origami in the literature [W. J. Aroa, H. I. Smith, and G. Barbastathis, Microelectron. Eng. 84, 1454 (2007); W. J. Aroa et al., J. Vac. Sci. Technol., B 25, 2184 (2007); and K. Chalapat et al., Adv. Mater. 25, 91 (2013)]. The experimental results indicate that the introduction of a microrobot inside the SEM vacuum chamber will provide the means to enlarge the scope of clean room facilities to build complex and smart 3D microsystems with heterogeneous materials, especially on the facet of an optical fiber in the lab on fiber new field. The authors propose a new way to easily manufacture many kinds of optical functions for light trapping based on nanoantennas, nanophotonic crystal, axicon or lattice, 3D biosensor with origami, and nanopatterning surfaces or carbon nanotubes, etc.In this study, the authors have demonstrated that it is possible to realize several three-dimensional (3D) micro- and nanostructures, by the fabrication of the smallest microhouse using a dual beam scanning electron microscope (SEM)/focused ion beam (FIB) Auriga 60 from Zeiss together with a six degree of freedom robot built with SmarAct components. In this new type of nanolab, cutting, etching, folding, assembling, and then welding thin membranes of silica on top of a cleaved optical fiber SMF28, or production of micro- and nanostructures, like the microhouse, are possible. The authors have experimentally shown that FIB can be used, in this new generation of micro/nanofactory, in combination with SEM, and gas injection system, in order to fabricate three-dimensional microstructures: a microhouse in this study, with ultrahigh accuracy assembly down to 10 nm. By using the theory of sputtering, the authors are able to propose a model of folding thin membranes of numerous materials such as metals, polymers, ...

This paper presents preliminary results on OCT (Optical Coherence Tomography) based control of a concentric tube robot (CTR). The potential use of OCT system is presented then its ability to perform an optical biopsy and an eye-to-hand configuration for robot control is highlighted. A prototype of CTR with three curved tubes is shortly described then a model-less OCT-based controller is detailed. The extraction of visual features from OCT images is performed by normalized cross-correlation. The proposed control scheme was experimentally validated. The positioning accuracy of CTR control was evaluated in benchtop trials. The error in tip placement can reach 10 μm along X and 74 μm along Y according to controller parameters. The 2D positioning (XY plan) is also tested then a final error about 55 μm is achieved.

International audience; Despite a large number of proofs of concept in nanotechnologies (e.g. nanosensors), nano electromechanical systems (NEMS) hardly come to the market. One of the bottlenecks is the packaging of NEMS which require handling, positioning, assembling and joining strategies in the mesoscale (from 100nm to 10 m, between nanoscale and microscale). It requires models of the interaction forces and adhesion forces dedicated to this particular scale. This paper presents several characteristics of the mesoscale in comparison with nanoscale and microscale. Firstly, it is shown that the distributions of charges observed on the micro-objects and meso-objects would have negligible effects on the nano-objects. Secondly, the impact of both chemical functionalisation and physical nanostructuration on adhesion are presented. Thirdly, the van der Waals forces are increased by local deformations on the mesoscale contrary to the nanoscale where the deformation is negligible. This article shows some typical characteristics of the mesoscale.

Today, the rapid advance of additive manufacturing, namely 3D printing, gives options and capabilities to simplify the fabrication of three-dimensional complex structures. In fact, such technology brings a real rupture comparing to conventional technologies in terms of design and manufacturing. Taking those advantages, this paper presents the design and the fabrication of a monolithic pivot articulation. First, the skeleton of the articulation is designed as a monolithic bloc. Then, the articulation is fabricated in one operation without assembly. To functionalize the articulation a Shape Alloy Memory (SMA) wire is utilized. Its advantage is the ease of integration thanks to the low diameter of the wire and the expected grooves within the printed structure, making possible the realization of miniaturized complex structures and the introduction of the actuation even inside this latter. The whole actuated structure has a centimeter size and serves as a proof of concept. Experiments are carried out to demonstrate the interest of the realized prototype and thus to highlight that 3D printing could be potential in the development of complex actuated structures.

System miniaturization remains an important challenge in the field of microrobotics. Several works have been raised in this context. Maybe the most known and widespread are MEMS devices based on clean room technologies. Although they give option to design small systems with mico/nano features, such technologies are limited to planar structures with two or three degrees of freedom (DOF). To tackle this limitation, a new approach is proposed in this paper. Instead of planar construction, we proposed here to design three-dimensional micro-systems by taking advantages of additive manufacturing technology, namely 3D printing. The final objective consists to design a monolithic structure in one operation without assembly. Then functionalization could be achieved by equipping the structure with actuators and sensors. Starting from the fact that any complex structure could be decomposed into basic elements such as articulations or flexures, this paper will focus on how articulations could be fabricated without assembly using 3D printing facilities. Combining those articulations which are considered as fundamental bricks will make possible to design complex monolithic structures. As an illustration, a pivot articulation is experimentally demonstrated using 3D printing.

International audience; A new piezoelectric actuator with collocated sensor is designed, modeled and simulated. The structure has three piezoelectric layers where the two external layers serve for the actuation by a convenient application of electrical potentials, and the middle layer serves as the sensor. After presenting the principle of the structure, a model is developed for the actuator and as well as for the sensor. Then simulation is carried out to evaluate their performances. The novel structure is very promising for applications that require control and automation, especially in situations where the use of sensors is unfeasible or difficult.

International audience; Adhesion between microgripper end-effector and a nano/micro-object is a main topic for manipulation in micro- and nanoscale. Tuning this force is a great challenge. Adhesion force is directly 2 linked to the chemical composition and the surface roughness of both, the object and the gripper. Recently, we proposed a multispheres Van der Waals force model able to predict this force. The surface used was structured by an array of polystyrene spheres with radii from 35 nm to 2 mm. The experimental pull-off forces have confirmed our model. In this present work, we analyzed other innovating structure such as non-closed packed polystyrene (PS) spheres and organized Si Nanostructures, formed by chemical etching. The adhesion values of the pull-off force measured on these structures were very low (in the range of 2 to 10 nN), and suggest that these new structures have non-adhesive properties. A new model taking in account the roughness and the organization of the PS spheres and Si Nanostructures has been developed to predict these new properties.

Electrochemical in situ preparation and morphological characterization of inorganic redox material-organic conducting polymer coatings as thin films on platinum electrodes are presented. Composite inorganic–organic coatings consist of Prussian blue (PB) and [poly(3,4-ethylenedioxythiophene)] (PEDOT), and PEDOT organic polymers doped with ferricyanide (PEDOT–FeCN). The PEDOT coating deposited from an aqueous solution containing the 3,4-ethylenedioxythiophene monomer and LiClO4 as supporting electrolyte was used as a “reference” material (PEDOT–ClO4). The composite coatings were prepared by electrochemical methods on platinum electrode chips, which consist of a 150 nm Pt layer deposited on 100-oriented standard 3″ silicon wafers. Electrochemical behavior of the composite inorganic–organic coatings is based mainly on inorganic component redox reactions. Different surface properties of the composite materials were studied. Thus, the roughness of the deposited films was measured by both atomic force microscopy (AFM) and profilometry, leading to roughness values ranging from 3 nm to 217 nm for PEDOT–ClO4, and PEDOT–FeCN and PEDOT–PB coatings, respectively. AFM and Scanning Electron Microscopy pictures were also produced to characterize the film morphologies, and revealed a granular pattern of the deposited inorganic component inside the organic polymer matrix. Moreover, the adhesion properties of the composites were studied by AFM and proved to be very different from one material to the other depending on the film structure. The electrochemical responses of these composite coatings to H2O2 reduction were also investigated using chronoamperometry. A linear response over a concentration range from 1 × 10− 4 to 1 × 10− 5 M and a detection limit of 10 μM were obtained.

International audience; This paper presents electrochemical synthesis of polypyrrole films under high frequency sonication. The films are characterized in terms of adhesion and surface morphology. Comparison to classical electrosynthesized polypyrrole films is made. In particular, the use of high frequency sonication (500 kHz) during electrodeposition of polypyrrole on Si was reported for the first time. Chronocoulometry was used for polymer films electrosynthesis on Si substrates. Influence of polymer thickness on the rugosity, morphology and adhesion force properties was studied. Scanning Electron Microscopy and mechanical probe profiling showed that sonication led to less rough and more homogeneous surface structure. Adhesion force properties of polypyrrole films were also studied by means of force-distance curves obtained by atomic force microscopy. For polymer films obtained in the absence of sonication, adhesion forces decreases with increase in polymer thickness. On the contrary, for polymer films obtained under sonication, the adhesion of the films decreased when the polymer thickness decreased.

International audience; At the microscale, surface forces influence the behaviour of micro-objects more than volumic forces. During micro-assembly processes, contacts occur between a microgripper and a micro-object or between a substrate and a micro-object. The pull-off force, which represents the force required to break a contact, is one of the predominant problems in micro-assembly. Current force measurements are mostly focused on sphere-plane geometries, and models are based on naoscale theories. The aim of this Letter is to propose an evaluation of the pull-off force for a planar contact, which is the most frequent kind of contact in micro-assembly. Experimental force measurements based on a capacitive microforce sensor and micro/nano robotic systems are carried out. The proposed device enables the study of pull-off forces according to the preload force and the contact angle. Finally, experimental results are discussed and compared with a model.

International audience; During microscale object manipulation, contact (pull-off) forces and non-contact (capillary, van der Waals and electrostatic) forces determine the behaviour of the micro-objects rather than the inertial forces. The aim of this article is to give an experimental analysis of the physical phenomena at a microscopic scale in dry and liquid media. This article introduces a review of the major differences between dry and submerged micromanipulations. The theoretical influences of the medium on van der Waals forces, electrostatic forces, pull-off forces and hydrodynamic forces are presented. Experimental force measurements based on an AFM system are carried out. These experiments exhibit a correlation better than 40 % between the theoretical forces and the measured forces (except for pull-off in water). Finally, some comparative experimental micromanipulation results are described and show the advantages of the liquid medium.

International audience; Robotic microhandling is a promising way to assemble microcomponents in order to manufacture new generation of Hybrid Micro ElectroMechanical Systems (HMEMS). However, at the scale of several micrometers, adhesion phenomenon highly perturbs the micro-objects release and the positioning. This phenomenon is directly linked to both the object and the gripper surface mechanical and chemical properties. The control of the adhesion properties requires multidisciplinary approaches including roughness control, mechanical properties control and chemical surface functionalisation. We propose to control adhesion by using chemical surface functionalisations by intrinsic conducting polymer electrodeposition or Self-Assembly Monolayer (SAM) and using surface structuration.

International audience; This paper presents the design of a mesoscale robot for laser phonosurgery. The proposed design is situated between conventional mechanism and MEMS technology.A combination of compliant structures and innovative micromotors enables to achieve two decoupled tilting angle, a high range (up to 45°) and a precise positioning of a laser beam. The design methodology and the optimization of the compliant structure are detailed. Preliminary results and tests are described which have induced promising performances of the mesoscale robot for laser steering.