A Tri-Mode Coupled Coil with Tunable Focal Point Adjustment for Bio-Medical Applications

TL;DR

This paper introduces a tri-mode coupled coil system with tunable focal point adjustment, optimized for biomedical applications like electromagnetic therapy and imaging, by controlling coil current ratios through frequency tuning.

Contribution

It presents a novel tri-mode coil design with adjustable electromagnetic focus, demonstrated by measuring coil current ratios and induced voltages in biological tissues.

Findings

Maximum current ratio of 13.0 at 487.7 kHz

Minimum current ratio of 0.258 at 453.2 kHz

Current ratio in third mode is 1.03

Abstract

The paper proposes the design of a tri-mode coupled coil which enables three modes of operation for inducing electromagnetic field, where the focal adjustment of the E field can be optimized. Methods: The setup consists of two identical figure-of-eight coils, namely coil 1 and coil 2, coupled to each other by magnetic resonance coupling. Coil 1 is driven by active source, where coil 2 is driven by the magnetic field coupled from coil 1. The frequency of operation would affect the coupling between the coils and hence the current ratios induced. Results: In the first and the second modes, the current dominates at the first coil and the second coil, respectively. In the third mode, both coils conduct similar amount of currents. Conclusion: The concept is proven by measuring the current ratios of the coils and the voltage induced in biological tissues. The current ratios in the first and the second modes are measured as maximum 13.0 and minimal 0.258 at frequencies 487.7 kHz and 453.2 kHz, respectively, while the current ratio measured in the third mode is 1.03. Significance: The tri-mode coil could potentially be applied for biological applications such as pulsed electromagnetic energy treatment and thermoacoustic imaging.