Hybrid Wireless Positioning and Charging With Switched Field Helmholtz Coils for Wireless Capsule Endoscopy

The state-of-the-art wireless positioning and wireless charging using magnetic coupling designed for wireless capsule endoscopy (WCE) require different magnetic field distributions and system structures. Due to the space and weight constraints of WCE, designing a system that achieves wireless positioning and wireless charging simultaneously becomes an emerging problem. A switched field structure based on the Helmholtz coils is proposed in this article to provide a gradient field distribution for wireless positioning and uniform field distribution for wireless charging by switching the excitation mode of the Helmholtz coils. Focusing on the wireless positioning function, the gradient mode of the Helmholtz coils is able to achieve a millimeter-level positioning accuracy and a degree level orientation accuracy along the z-axis within the effective space. The proposed method provides a feasible way to achieve wireless positioning and charging using the same system structure to meet the requirements of wireless capsule endoscopy and other related biomedical and industrial applications.