Individual Difference Frequency Adaptive Adjustment Method for Magnetic Resonant Human Body Communication

Magnetic resonant human body communication (MR-HBC) features ultra-low power consumption under resonance conditions, with flexible electrode configurations that enable contactless communication, making it suitable for various body area network applications. However, the resonance state is susceptible to the influence of different human body, leading to detuning and frequency shifts, which can cause communication interruptions. This paper proposes an adaptive adjustment method to address resonance frequency variations caused by individual differences, locking the resonance frequency by minimizing the reflection coefficient, ensuring that the MR-HBC system maintains high-quality communication resonance across different scenarios. Finite element analysis and in vivo experiments were conducted to investigate the effects of varying body fat content and different skin conditions, validating the accuracy and effectiveness of the adaptive adjustment system. The results show that resonance frequency fluctuations caused by individual differences are within 1.02 MHz, with a variation of up to 9.3%.Frequency variations result in a maximum increase of 14.53 dB in path loss, with inter-individual path loss differences reaching up to 28.9%. The integration of the adaptive adjustment system resulted in notable improvements, limiting the maximum locking error to 0.031 MHz, achieving an average enhancement of 12.96 dBm, and reducing MR-HBC transmission path loss by an average of 32.57%.