Ultra-low-power implantable medical devices: Optical wireless communication approach

Implantable medical devixes (IMDs) have been gaining increasing interest for their advantages of precise monitoring and diagnostics of chronic diseases. The usefulness of IMDs resides in improving the power efficiency of the implantsto- surface communication, which consumes most of the battery power. To tackle this challenging requirement, this article introduces a novel optical wireless communication approach that employs an unsynchronized pulse interval modulation technique dedicated to IMDs. A design principle for ultra-low-power optical wireless communication is addressed, and a prototype design is implemented within a small form factor of 10 mm ´ 10 mm ´ 2.3 mm. Experiments over biological channels ensure that the transmitted signal penetrates skin samples in various ranges of thickness with sub-milliwatt-level power consumption as low as 392 mW. Finally, technical challenges that will be faced in the extension of applications are discussed. The developed approach opens new opportunities for realizing ultra-low-power communication electronics for viable future applications in wireless communications, including medical devices, inter-chip communication, and free-space optics.