Design and Implementation of a Low Power Wireless Frequency-Division Multiplexed Magnetic 3D Localization Scheme With Sub-mm Precision for Capsule Endoscopy Applications

This letter presents a new magnetic localization scheme based on frequency-division multiplexing for capsule endoscopy applications. The approach significantly reduces the reference excitation coil sizes and decreases the required excitation current by three orders of magnitude compared to prior work, making it practical for wearable systems. Different spatial configurations of the reference coils are considered and simulated to provide design insight for maximizing localization accuracy. A fully integrated wireless receiver prototype is implemented in 180-nm bulk CMOS and packaged in an ingestible pill form factor. To the best of our knowledge, the new scheme achieves the best experimentally demonstrated tracking accuracy in both 2D and 3D localization experiments, achieving a sub-mm mean absolute position error and consuming only
$336~\mu \text{W}$
while running at 100% duty cycle.