Using pot-magnets to enable stable and scalable electromagnetic tactile displays


We present the design, fabrication, characterization and psychophysical testing of a scalable haptic display based on electromagnetic (EM) actuators. The display consists of a 4×4 array of taxels, each of which can be in a raised or a lowered position, thus generating different static configurations. One of the most challenging aspects when designing densely-packed arrays of EM actuators is obtaining large actuation forces while simultaneously generating only weak interactions between neighboring taxels. In this work we introduce a lightweight and effective magnetic shielding architecture. The moving part of each taxel is a cylindrical permanent magnet embedded in a ferromagnetic pot, forming a pot-magnet. An array of planar microcoils attracts or repels each pot-magnet. This configuration reduces the interaction between neighboring magnets by more than one order of magnitude, while the coil/magnet interaction is only reduced by 10%. For 4 mm diameter pins on an 8 mm pitch, we obtained displacements of 0.55 mm and forces of 40 mN using 1.7 W. We measured the accuracy of human perception under two actuation configurations which differed in the force vs. displacement curve. We obtained 91% of correct answers in pulling configuration and 100% in pushing configuration.
Published in: IEEE Transactions on Haptics ( Volume: PP, Issue: 99 )
DOI: 10.1109/TOH.2016.2591951

Paper in ACS Applied Materials and Interfaces


The ACS Applied Material and Interfaces has accepted a paper from partners of the BlindPAD consortium. It will be published


Title: Highly Magneto-Responsive Elastomeric Films Created by a Two-Step Fabrication Process (ACS Appl. Mater. Interfaces20157 (34), pp 19112–19118)

Authors of the paper:

  • Sophie Marchi, Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
  • Alberto Casu, Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy; Biological and Environmental Sciences and Engineering Division, King Abdullah University for Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia
  • Franco Bertora, Robotics Brain and Cognitive Science, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
  • Athanassia Athanassiou, Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
  • Despina Fragouli, Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy


ABSTRACT: An innovative method for the preparation of elastomeric magnetic films with increased magneto-responsivity is presented. Polymeric films containing aligned magnetic microchains throughout their thickness are formed upon the magnetophoretic transport and assembly of microparticles during polymer curing. The obtained films are subsequently magnetized at a high magnetic field of 3 T directed parallel to the orientation of the microchains. We prove that the combination of both alignment of the particles along a favorable direction during curing and the subsequent magnetization of the solid films induces an impressive increase of the films’ deflection. Specifically, the displacements reach few millimeters, up to 85 times higher than those of the nontreated films with the same particle concentration. Such a process can improve the performance of the magnetic films without increasing the amount of magnetic fillers and, thus, without compromising the mechanical properties of the resulting composites. The proposed method can be used for the fabrication of magnetic films suitable as components in systems in which large displacements at relatively low magnetic fields are required, such as sensors and drug delivery or microfluidic systems, especially where remote control of valves is requested to achieve appropriate flow and mixing of liquids.



Image on the differences on Homogeneous Dispersion and Alignment and Post-Magnetization


KEYWORDS: PDMS, microparticles, magnetic assembly, ferromagnetism, magnetic actuation


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