Flexible magnetic force sensors: manufacture, mechanisms, and applications

In recent years, flexible magnetic sensors have undergone rapid development in cutting-edge fields such as wearable devices, robotic hand interaction, and soft robotics, demonstrating remarkable performance in sensitivity, multi-dimensional force perception, and deformability. The core component of these sensors is a flexible magnetic film, fabricated by blending magnetic particles with a soft polymer matrix using specific forming processes. Flexible magnetic force sensors work by decoding the link between magnetic signals and mechanical forces to sense touch. This review systematically examines the research framework of flexible magnetic sensors for force sensing from four critical dimensions. First, the manufacturing processes are analyzed, including the preparation of soft magnetic functional films and commonly used magnetosensitive elements. Subsequently, two primary force-decoupling methodologies are discussed: analytical modeling and data-driven approaches, with a comparative evaluation of their respective strengths and limitations. The review summarizes the key performance characteristics of flexible magnetic sensors, focusing on sensitivity, multi-dimensional force detection and deformability. Furthermore, emerging applications in wearable devices and robotic hand interaction are highlighted, illustrating the capability of these sensors for high precision feedback and multi-axis force decoupling. Finally, we assess several key challenges. These include performance variation due to non-uniform magnetic particle distribution, which necessitates laborious calibration, and signal drift following repeated use. Future directions, including bioinspired designs and artificial intelligence enhanced system integration, are also outlined. By synthesizing these perspectives, we aim to advance research toward higher sensing performance and broader application horizons for flexible magnetic sensors.