Elastic Magnetic Materials and Sensors for Tactile Perception

The growing demand for wearable and implantable devices, as well as human-machine integration, is accelerating the development of flexible and stretchable electronic materials. Flexible magnetic sensors merge the conformability and portability of soft electronics with the contactless and vector-sensing capabilities of magnetic elements, enabling new functions such as tactile perception for use in humanoid robotics and virtual reality.

This talk focuses on magnetic tactile sensors to discuss key challenges in achieving flexibility, including poor stress stability, the conductivity-stretchability trade-off, fracture-prone sensor arrays, and limited recovery of magnetic elastomers. Our research explores how strain and strain gradients affect magnetic domain structures in flexible ferromagnetic/antiferromagnetic systems. Via interface design and strain-engineering, we developed strain-insensitive ferromagnetic films and exchange-biased heterostructures. Using microfabrication methods, we prepared high-density flexible spin-valve arrays (400 units/cm²). By designing modulus-graded structures with liquid metal interconnects, we realized spin-valve arrays capable of withstanding up to ~80% omnidirectional strain. We also improved sensor recovery and dynamic range through modulus control and magnetic structural optimization. Based on these advances, we fabricated flexible 3D force magnetic tactile sensors, bio-inspired digital tactile sensors, and multi-modal tactile sensors. Together, these results provide a foundation for enhancing the performance of flexible magnetic tactile sensors.