A flexible strain gauge exhibiting reversible piezoresistivity based on an anisotropic magnetorheological polymer

MIETTA, J.L.; G. A. JORGE; NEGRI, R.M.

SMART MATERIALS & STRUCTURES

IOP PUBLISHING LTD

Año: 2014 vol. 23 p. 85026 - 85038

0964-1726

Abstract A flexible, anisotropic and portable stress sensor (logarithmic reversible response between 40-350 kPa) was fabricated, where i) the sensing material, ii) electrical contacts and iii) encapsulating material, are based on polydimethylsiloxane (PDMS) composites. The sensing material is a slide of an anisotropic magnetorheological elastomer (MRE) formed by dispersing silver-covered magnetite particles (Fe3O4@Ag) in PDMS and curing in the presence of a uniform magnetic field. Thus, the MRE is a structure of electrically conducting pseudo-chains (needles) aligned in a specific direction, which electrical conductivity increases when stress is applied in the direction of the needles, exclusively. Electrical conductivity appears only between contact points which face each other at both sides of the MRE slide. An array of electrical contacts was implemented based on PDMS-silver paint metallic composites. The array was encapsulated with PDMS. Using Fe3O4 superparamagnetic nanoparticles opens possibilities for a magnetic field sensor also, because of magnetoresistance effects. KeyWords: structured magnetoelastomer composites. flexible stress sensor, piezoresistivity, electrically conductive composites