Michal Stanislaw Smreczak | EPFL Graph Search

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

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

Flexure pivot based system

Benoît Dagon, Simon Nessim Henein, Michal Stanislaw Smreczak, Loïc Benoît Tissot-Daguette

Flexure pivot based system (1) being one of: a force sensor, a force limiting device arranged to exert a predetermined threshold force, a torque limiting device arranged to exert a predetermined threshold torque, a programmable mechanical memory, or an accelerometer, said flexure pivot based system (1) comprising a substantially rigid frame (3) supporting a lever (5) by means of a suspension mechanism (7) comprising: - a first flexure (9) extending from said frame (3) to a junction (15) with said lever (5); - a second flexure (11) extending from said frame (3) to said junction (15) and arranged at a first non-zero angle to said first flexure (9) in a neutral position of said suspension mechanism (7), - a third flexure (13) extending from said junction (15) to a preloading system (17) at a second non-zero angle to at least one of said first flexure (9) and said second flexure (11) in a neutral position of said suspension mechanism, said preloading system (17) being arranged to apply a force in a direction substantially coaxial with said third flexure (13).

2022