Video-Capable Ultrasonic Wireless Communications Through Biological Tissues.

Area of Science:

• Biomedical Engineering
• Wireless Communication
• Medical Devices

Background:

• Wireless implanted medical devices (IMDs) offer patient convenience and reduced infection risk compared to wired systems.
• Current radio frequency (RF) communication for IMDs is limited to 267 kb/s, insufficient for high-data-rate applications like video streaming.
• Existing RF technology faces bandwidth and power limitations, hindering advanced functionalities for IMDs.

Purpose of the Study:

• To introduce and evaluate an alternative high-data-rate communication method for IMDs using ultrasonic waves.
• To overcome the data rate limitations of current RF-based IMDs.
• To enable new applications such as real-time video streaming from implanted devices.

Main Methods:

• Developed an advanced quadrature amplitude modulation (QAM) modem with a phase-compensating, sparse decision feedback equalizer (DFE).
• Tailored the modem to optimize performance over the ultrasonic channel within biological tissues.
• Conducted simulations using finite impulse response (FIR) channel models and performed physical transmission experiments.

Main Results:

• Simulations confirmed that video-capable data rates are achievable with millimeter-sized ultrasonic transducers.
• Physical experiments demonstrated high data rates: 6.7 Mb/s in water, 4.4 Mb/s in ex vivo beef liver, 4 Mb/s in ex vivo pork chop, and 3.2 Mb/s in situ rabbit abdomen.
• The ultrasonic system successfully transmitted data at rates significantly exceeding current RF capabilities for IMDs.

Conclusions:

• Ultrasonic wave communication presents a viable solution for achieving high data rates in wireless implanted medical devices.
• The developed QAM modem effectively utilizes the ultrasonic channel through biological tissues.
• This technology paves the way for advanced IMD applications requiring high bandwidth, such as medical imaging and real-time monitoring.