Split Frequency and Load-Shift Keying Based Bi-directional Data Transfer Technique in Wireless Implantable Medical...

Area of Science:

• Electrical Engineering
• Electromagnetics
• Wireless Power Transfer

Background:

• Power frequency splitting is a known phenomenon in wireless power transfer (WPT) systems under critical coupling.
• This splitting affects voltage gain and power delivered to the load (PDL), but not power transfer efficiency.
• Existing models analyze characteristic frequencies and circuit parameters in series-parallel WPT systems.

Purpose of the Study:

• To analyze the 'power frequency splitting' phenomenon in wireless series-parallel systems.
• To propose a novel co-simulation platform for modeling frequency-dependent resistance in flexible polymer coils.
• To develop a protocol for simultaneous wireless power and bidirectional data transmission.

Main Methods:

• Utilized a mutual inductance model to analyze characteristic frequencies and circuit parameters.
• Developed a co-simulation platform integrating ANSYS MAXWELL and SIMPLORER for dynamic modeling.
• Implemented a single-link protocol using Frequency Shift Keying (FSK) for downlink and Load Shift Keying (LSK) for uplink data transfer.
• Incorporated a tertiary coil for receiving and decoding backscattered data.

Main Results:

• Demonstrated that the split frequency-based FSK modulation allows continuous wireless power transmission during data transfer.
• Achieved high data rates and high power transfer efficiency.
• Identified a trade-off between link gain, bandwidth, and efficiency that limits the technique's range.
• Confirmed that the three-coil architecture does not alter split point locations but slightly reduces link gain.

Conclusions:

• The proposed split frequency-based data transfer technique effectively enables simultaneous wireless power and bidirectional data transmission.
• The co-simulation platform provides accurate dynamic modeling of frequency-dependent resistance in flexible coils.
• System performance is constrained by the distance due to bandwidth and efficiency trade-offs, suggesting further optimization is needed for long-range applications.