Chronic monitoring of nerve activity with minimally invasive medical devices creates broad opportunities from therapeutic treatments to human augmentation. These closed-looped neural recording and modulation systems require small, low power wearable devices to enable freely moving subjects while still allowing real- time processing of recorded data. An ultrasonic backscatter system called Neural Dust (ND) demonstrated ultrasound's increased power efficiency over electromagnetic (EM) energy for sub-mm scale implantable devices used for wireless electrophysiological neural recording. Although wireless neural recording reduces invasiveness, the technique’s inherent energy losses compared to wired solutions constrain the power and size of the device interacting with the implant. Additionally, ultrasound’s increased power efficiency for sub- mm scale implantable devices over EM energy coupling allows for smaller implantable devices but shifts the burden to the system’s ultrasound transceiver, as conventional ultrasound systems consume more power than RF transceivers. A custom, single 1.8V supply ultrasonic interface ASIC with high power efficiency is used to overcome these limitations. In this work, integrating the ultrasonic interface ASIC with off-the-shelf components produced a wearable ultrasound system that enables untethered, chronic neural recording and real-time processing.
Project end date: 08/15/17