Papers by Sebastian Fifanski
VivoForce - Force sensitive hook for epiretinal membrane peeling in eye surgery
Flexure-based mecano-optical multi-degree-of-freedom transducers dedicated to medical force sensing instruments
This project addresses the design, construction and evaluation of a peeling hook with force measu... more This project addresses the design, construction and evaluation of a peeling hook with force measurement capability for in-vivo intra-ocular vitreoretinal surgery. The force sensor consists of a miniature multi-degree-offreedom flexure where deformations induced by contact forces are measured using optical fiber white light interferometry. This instrument will be used for epiretinal membrane peeling procedures and should then lead to the creation of a new generation of force sensitive surgical tools.
This paper presents novel multi-degrees-of-freedom force sensors based on flexures used as mecano... more This paper presents novel multi-degrees-of-freedom force sensors based on flexures used as mecano-optical transducers (named flexure body) and white light interferometers used as opto-electrical transducers. Together, these transducers make up a load cell exploiting the nanometric accuracy of Fabry-Perot interferometric measurement to reach milli-Newton force accuracy. The design focuses on the flexure body composed of three sections: a base (attached to the measuring device), a compliant section which deforms under applied forces and a pointed rigid section whose tip touches tissues during surgery. The fiber interferometer measures the distal displacement with respect to the base using one 125 μm diameter optical fiber for each load cell DOF. The key advantages of this design are: compact design (1 to 4 mm diameter shaft), simple optical alignment during assembly, scalability from Newton down to milli-Newton force levels, insensitivity to electrical charge and compatibility with st...
Résumé Depuis son introduction en 1675, le balancier-spiral est la base de temps exclusive de la ... more Résumé Depuis son introduction en 1675, le balancier-spiral est la base de temps exclusive de la montre mécanique. Or cet oscillateur présente deux difficultés limitatives qui n'ont jusqu'à présent pas été contournées : un facteur de qualité limité (en particulier par des phénomènes tribologiques), ainsi que la nécessité d'un échappement, mécanisme complexe au rendement limité. Cet article pré-sente un nouvel oscillateur appelé IsoSpring, qui améliore le facteur de qualité grâce au recours aux guidages flexibles et élimine complètement l'échappement. Le concept de ce nouvel oscillateur qui est doté de deux degrés de liberté remonte à Issac Newton. Il est replacé dans le contexte historique des principales avancées conceptuelles en horlogerie mécanique. La résolution des équa-tions du mouvement démontre que l'inertie des organes tournants perturbe l'isochronisme. Pour pallier cette limitation, des architec-tures de mécanismes à guidages flexibles supprimant l&...
Precision Engineering, 2016
We define isotropic springs to be central springs having the same restoring force in all directio... more We define isotropic springs to be central springs having the same restoring force in all directions. In previous work, we showed that isotropic springs can be advantageously applied to horological time bases since they can be used to eliminate the escapement mechanism [7]. This paper presents our designs based on planar serial 2-DOF linear isotropic springs. We propose two architectures, both based on parallel leaf springs, then evaluate their isotropy defect using firstly an analytic model, secondly finite element analysis and thirdly experimental data measured from physical prototypes. Using these results, we analyze the isotropy defect in terms of displacement, radial distance, angular separation, stiffness and linearity. Based on this analysis, we propose improved architectures stacking in parallel or in series duplicate copies of the original mechanisms rotated at specific angles to cancel isotropy defect. We show that using the mechanisms in pairs reduces isotropy defect by one to two orders of magnitude.
Flexure-based multi-degree-of-freedom force and torque sensors at the milimeter scale for medical instruments
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Papers by Sebastian Fifanski