A Cotton Fabric Composite with Light Mineral Oil and Magnetite Nanoparticles: Effects of a Magnetic Field and Uniform Compressions on Electrical Conductivity

Abstract

Over the past few decades, tactile sensors have become an emerging field of research with direct applications in the area of biomedical engineering. New types of tactile sensors, called magneto-tactile sensors, have recently been developed. The aim of our work was to create a low-cost composite whose electrical conductivity depends on mechanical compressions that can be finely tuned using a magnetic field for magneto-tactile sensor fabrication. For this purpose, 100% cotton fabric was impregnated with a magnetic liquid (EFH-1 type) based on light mineral oil and magnetite particles. The new composite was used to manufacture an electrical device. With the experimental installation described in this study, we measured the electrical resistance of an electrical device placed in a magnetic field in the absence or presence of uniform compressions. The effect of uniform compressions and the magnetic field was the induction of mechanical–magneto–elastic deformations and, as a result, variations in electrical conductivity. In a magnetic field with a flux density of 390 mT, in the absence of mechanical compression forces, a magnetic pressure of 5.36 kPa was generated, and the electrical conductivity increased by 400% compared to that of the composite in the absence of a magnetic field. Upon increasing the compression force to 9 N, in the absence of a magnetic field, the electrical conductivity increased by about 300% compared to that of the device in the absence of compression forces and a magnetic field. In the presence of a magnetic flux density of 390 mT, and when the compression force increased from 3 N to 9 N, the electrical conductivity increased by 2800%. These results suggest the new composite is a promising material for magneto-tactile sensors.

Electric Capacitors Based on Silicone Oil and Iron Oxide Microfibres: Effects of the Magnetic Field on the Electrical Susceptance and Conductance

“…The susceptance increased over time, indicating the capacitors' ability to dynamically adjust their electrical properties in response to external magnetic fields, consistent with trends reported in studies involving magnetodielectric composites (Andrei et al [24]). Conversely, conductance decreased with increasing magnetic flux density, highlighting the magnetic field's influence in controlling conductive pathways within the dielectric medium, as observed by Iacobescu et al [28]. The temporal stability of both conductance and susceptance suggests that the capacitors maintain consistent performance under continuous exposure to the magnetic field, essential for reliable operation in practical applications.…”

“…The obtained data are analyzed to demonstrate that in a medium-frequency electric field, both electrical conductance and susceptance can be coarsely adjusted by varying the ratio of SO to microfibers and finely tuned by the magnetic flux density. Compared to the capacitors produced in [24][25][26][27][28], this study shows that the presence of semiconductor iron oxides in the microfibers alters the behaviour of electrical conductance when a magnetic field is applied. A theoretical model based on dipolar approximations is proposed to explain the underlying physical mechanisms governing the electrical properties of the capacitors.…”

“…It is well-known that in a magnetic field, the solid phase, in the form of ferri-ferromagnetic nanomicroparticles, forms aggregates within the liquid matrix [24,27,28]. This effect transforms the liquid from Newtonian to non-Newtonian [36,37].…”

“…Additionally, there are capacitors based on silicon oil (SO) and magnetizable nano-microparticles. In these capacitors, the equivalent electrical components can be adjusted magnetically [24][25][26][27][28].…”

“…In these capacitors, electrical conductance is coarsely adjusted by the ratio of honey to turmeric quantities and finely tuned by the intensity of the electric field. Iacobescu et al [28] produced capacitors using cotton fabric impregnated with a magnetic liquid based on mineral oil and magnetite nanoparticles. By maintaining a constant quantity of magnetic liquid, it was observed that the electrical conductance of the composite can be coarsely adjusted by applying compressive stress and finely tuned by the values of the magnetic flux density.…”