Pressure-insensitive magnetic shear force sensor with pillar structure for versatile application

A flexible shear force sensor, exhibiting pressure-insensitivity, high sensitivity, and bidirectional measurement capabilities, is developed using a slender and flexible planar hall magnetoresistive (PHMR) sensing element combined with a pillar structure. The pillar structure, placed atop the PHMR sensing element, minimizes the influence of normal force on the sensor, enhancing its shear force sensing ability. This sensor features a 2.5 mm diameter pillar structure and measures bidirectional shear forces within a dynamic range of -0.1 N to 0.1 N, with a resolution of 0.4 mN and a sensitivity of 10 mV/N. The vertical force sensitivity is 500 times smaller than the shear force sensitivity, ensuring precise shear force measurements. This design simplifies signal monitoring, enabling accurate and precise measurements. Our sensor exhibits exceptional repeatability and nonhysteresis in shear forces, affirming its stability and reliability. These characteristics establish its suitability for measuring water and air flow velocities and various experimental applications, including braille reading. This shear force sensor, showcased in our study, demonstrates consistent performance across diverse environments, indicating its potential for applications requiring precise control and detection, such as robotic fingers, medical devices, and wearable monitoring systems.