Flexible Tactile Sensors with Self-Assembled Cilia Based on Magnetoelectric Composites

Traditional tactile sensors are single-function, and it is difficult to meet the needs of applications in complex environments. This paper describes the development and applications of flexible tactile sensors with cilia based on magnetoelectric composites made of neodymium iron boron (NdFeB) microparticles with a silver (Ag) nanoshell in polydimethylsiloxane (PDMS). These sensors adopt the inherent magnetism of NdFeB microparticles and the excellent conductivity of the Ag coating. Self-assembly of the composites of NdFeB@Ag/PDMS under the combined effect of intrinsic magnetism and external magnetic field yields cilia that are sensitive to forces with a high conductivity of 36479.33 S/m. The resulting sensors can measure forces in the range of 0.02-0.05 N and recognize surrounding magnetic fields whose magnitudes are larger than 10 mT. These sensors have been used to perform texture recognition, Braille recognition, and object recognition to yield accuracies of 98%, 100%, and 94.58%, respectively. This research based on NdFeB@Ag magnetoelectric microparticles presents a convenient approach to construct tactile sensors with randomly distributed surficial microstructures, leading to the prevalence of low-cost but highly sensitive tactile sensors for humanoid, human machine interface, and healthcare.