Simon Nessim Henein

Born in 1973 and of Egyptian-Swiss nationality, Simon Henein grew up in Cairo. He obtained an engineering degree at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in 1996 and went on to complete his doctorate at the EPFL in 2000. In 2001, he published the book “Conception des guidages flexibles” which has become a reference in precision engineering. He then joined the Centre Suisse d’Electronique et Microtechnique (CSEM), Neuchatel, Switzerland, where he conceived and developed mechanisms for robotic, aerospace, medical and watchmaking applications. He pursued his research career at the Paul Scherrer Institute, Villigen, Switzerland, where he developed instruments for the Swiss Light Source Synchrotron (SLS). Since November 1st, 2012, he is associate professor in microengineering at the EPFL, holder of the Patek Philippe Chair and director of the Micromechanical and horological design laboratory (Instant-Lab).

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HUM-441: Collective creation: improv-arts & engineering I

Les techniques d'improvisation développées dans les arts vivants (théâtre, musique, danse, performance) sont mises en perspective avec les pratiques de conception en ingénierie. Ce cours enseigné à l'Arsenic mène à une performance publique intégrant les performeurs et leurs réalisations techniques.

HUM-443: Collective creation: improv-arts & engineering II

MICRO-201: Mechanism Design II

Le second semestre du cours « Conception de mécanismes » développe les capacités créatrices de conception appliquées au domaine des mécanismes microtechniques. Il s'attache tant aux connaissances (composants, principes physiques, dimensionnement) qu'au processus cognitif de la conception en groupe.

Oscillation

Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar example

Quantum harmonic oscillator

The quantum harmonic oscillator is the quantum-mechanical analog of the classical harmonic oscillator. Because an arbitrary smooth potential can usually be approximated as a harmonic potential at th

Force

In physics, a force is an influence that can cause an object to change its velocity, i.e., to accelerate, unless counterbalanced by other forces. The concept of force makes the everyday notion of pus

Damping of flexure blades based on bi-material additive manufacturing

Nicolas Blondiaux, Florent Alexandre Boudoire, Florent Cosandier, Simon Nessim Henein, Nikola Kalentics, Lisa Salamin, Loïc Benoît Tissot-Daguette

Flexure-based mechanisms have become state-of-the-art solutions for the design of high-precision mechanisms, free from friction wear, backlash, and lubrication. These properties which are necessary for applications in ultraclean or harsh environments, nevertheless usually come with the drawback of very high quality factors. High quality factors can lead to adverse vibrations in the case of highly dynamic motions, or even fractures in the case of mechanical resonances. In space applications for instance, the mechanisms experience shocks and vibrations resulting from the rocket launch and from the other subsystems during operation. To tackle this challenge, CSEM developed and validated a concept of damped flexure blades based on bi-material additive manufacturing. The blades consist of a sandwich of two planar parallel metallic lattice patterns with an elastomer impregnated in-between (125 μm gap). The blades are made of 17-4PH stainless steel manufactured by Laser Powder Bed Fusion. The damping effect results from the energy dissipation occurring in the viscoelastic material as the blades and the elastomer deform. These blades were assembled in a simple parallel-spring-stage configuration and characterized under free and forced sinusoidal oscillations. Compared with reference mono-material “undamped” flexures, the damped flexures show quality factors Q reduced by a factor of 64. This reduction implies an improved damping action with a calculated viscous damping coefficient increased by a factor of 97. These first experimental results open promising perspectives for compliant mechanisms operating under vibrations and shocks. Moreover, new types of dampers could be developed based on the presented designs.

2023

A load cell with adjustable stiffness and zero offset tuning dedicated to electrical micro- and nanoprobing

Charles Baur, Simon Nessim Henein, Michal Stanislaw Smreczak, Etienne Frédéric Gabriel Thalmann, Loïc Benoît Tissot-Daguette

The tasks of electrical micro- and nanoprobing require precision that goes beyond human perception and therefore, depend on sensors providing real-time feedback. Efforts towards automation in micro- and nanoprobing and emerging areas such as branched nanowire networks, has resulted in a growing number of applications where electrical probing without simultaneous force control is insufficient. This article presents the design of a novel mesoscale flexure-based load cell dedicated to micro- and nanoprobing. By integrating systems for stiffness adjustment and a zero offset tuning, the force-displacement characteristic of the device can be adapted to suit a wide range of applications, from the measurement of large forces up to 60 mN to a resolution as high as 10.1 nN, and even negative stiffness (bistable) behavior. By controlling the tuning during measurements, a virtual dynamic range of 6.38 ⋅ 106 is achievable, which is one order of magnitude greater than existing commercial products. We validated the results experimentally on a titanium alloy prototype fabricated by electrical discharge machining (EDM). Experimental and finite element results were also used to validate the analytical model of the load-cell. Additionally, the device allows for probe tip replacement, which is a significant advantage compared to existing MEMS load cells, and comprises a gravity compensation system to accommodate a wide range of commercially available probe tips.

2022

Active load cell with positive, negative and zero stiffness operating modes for micronewton range contact force monitoring in electrical probing

Charles Baur, Simon Nessim Henein, Hubert Pierre-Marie Benoît Schneegans, Michal Stanislaw Smreczak

This article describes a novel method for applying a contact force in the range of 1 to 100 μN with pointed probe on a microscale sample in order to perform ohmic electrical measurements. The solution is based on the new TIVOT active load cell combining the functions of a force sensor and an actuator. Probe movement is performed by a piezo actuator which allows the probe tip to be moved over a 5.64 mm range with submicrometric precision. Force measurement is enabled by measuring the elastic deformation of a compliant structure with adjustable stiffness. Strategies are presented to remotely adjust the sensitivity of the mechanism leading to resolutions from 12 μN to 10 nN for forces ranges from 0-60 mN to 0-1 mN respectively. The piezo-actuated stiffness adjustment enables the mechanism to operate in a bistable mode with a tunable maximal threshold force, thus protecting the probe and sample from overloads. Zero offset tuning, in combination with the non-linear characteristic of the mechanism, allows reaching a quasi-constant force characteristic after landing the probe which helps maintaining a stable electrical contact during measurement. Experimental results show that this approach secures and improves probe to sample contact force leading to more efficient measurements than with the traditional methods.

2022