Magnetoelastic Torque Sensor with GaAs Hall Plates for E-Bikes

Typical e-bikes magnetoelastic torque sensors employ bulky fluxgate magnetometers to resolve few $\mu \mathbf{T} / \mathbf{N m}$. Instead, we propose the use of a miniaturized gradiometric arrangement of GaAs Hall plates sensitive to the radial magnetic field and a design approach that reduces the impact of axial misalignment. The proposed architecture provides comparable performance to commercial solutions, with reduced sizing and simplified magnetization requirements. Experiments conducted on a prototype with a full-scale (FS) upper limit of 200 Nm show a resolution of $7 \text{mNm}/\sqrt{\mathrm{H}\mathrm{z}}$ with a combined standard error of 1.85%FS.