Magnetic braille using ferrofluids

A M Fletcher,K O’Grady,A Hirohata,D Clarke,J S P Downs,W Frost

doi:10.1088/1361-6463/abe820

Abstract

Braille provides an invaluable tactile reading system for the visually impaired. However, current braille keyboards and technology are external mechanical devices limited by their large form factor, high expense and long refresh rates. A magnetic touchpad in which braille dots are formed through a ferrofluid medium is a potential device that could promise to replace current braille technology by providing higher refresh rates, lower cost and give easy integration into current devices. In this report, work is shown towards developing a proof of concept magnetic braille touch pad, wherein a braille dot is formed using a ferrofluid by a controlled magnetic field produced by a small scale electromagnet. Attempted optimisation of braille dot formation is also undertaken, varying ferrofluid properties and electromagnet architecture to form accurate braille dots. Results show that magnetic braille touch pads are realistic devices that can be built and that there are clearly extensive opportunities for further research. In the future magnetic braille touch pads could be fully implemented into information technology devices for use by the visually impaired.

Highlights

Braille is a tactile reading and writing system used by the visually impaired
We have modelled the design to optimise braille dot formation due to magnetic nanoparticles (MNPs) diameters and ferrofluid density to maximise the dot diameter and definition
At a magnetic field of 24.3 kA m−1, the measured height, 0.51 ± 0.05 mm, is within the UK Association for Accessible Formats (UKAAF) regulations for a braille dot which requires a diameter of 1.5 ± 0.25 mm and a height of 0.50 ± 0.10 mm

Summary

Introduction

Braille is a tactile reading and writing system used by the visually impaired. Braille dots are arranged in a 2 × 3 cell which can be used to represent letters, numbers and mathematical symbols to a visually impaired person. Where η is the viscosity of the fluid and VH is the hydrodynamic volume of the particle or aggregate In practice both modes of reversal are present in most samples of ferrofluid but even for the bulk rotation mechanism the relaxation time depending on the viscosity of the carrier fluid, is typically of the order of microseconds or at worst milliseconds depending upon the size of the aggregate. This allows for a high refresh rate due to a small relaxation time that could be integrated into information technology devices. We have modelled the design to optimise braille dot formation due to MNP diameters and ferrofluid density to maximise the dot diameter and definition

Magnetic field simulations

Magnetic braille fabrication

Results and discussion

Data availability statement