Backward Data Transfer From Deeply Implanted Device Employing Ultrasonic Load Amplitude-Phase Shift Keying

Area of Science:

• Biomedical Engineering
• Acoustic Engineering
• Implantable Devices

Background:

• Ultrasonic transcutaneous energy transfer (UTET) is crucial for wirelessly powering miniature implanted devices.
• Backward data transfer from implants often utilizes load modulation, reflecting ultrasonic energy.
• Existing methods like ON-OFF keying (OOK) have limitations in efficiency and data rate.

Purpose of the Study:

• To explore advanced load modulation techniques for backward data transfer in UTET systems.
• To introduce and demonstrate phase shift keying (PSK) for improved ultrasonic data transmission.
• To enhance energy efficiency and data signaling schemes for ultrasonic channels.

Main Methods:

• Investigated load phase shift keying (LPSK) by imposing reactive loads on implanted transducers.
• Exploited the phase characteristics of a matched transducer near its vibration resonance.
• Utilized finite-element simulation to demonstrate backward data transfer with two-state phase modulation at 20 kbit/s.

Main Results:

• Successfully demonstrated LPSK by exploiting the acoustic impedance dependency of piezoelectric resonators on electrical loading.
• Achieved a bit rate of 20 kbit/s using a 250 kHz ultrasonic carrier frequency in simulations.
• Showcased the potential for high-order signaling schemes by combining amplitude and phase shift keying.

Conclusions:

• Phase shift keying offers a more energy-efficient and higher-order signaling scheme for backward data transfer in UTET.
• LPSK modulation effectively utilizes the ultrasonic channel, improving data transfer capabilities for implanted devices.
• The demonstrated simulation results support the theoretical framework for advanced ultrasonic communication in implants.