ABSTRACT
OBJECTIVE: The goal of this paper is to create a large wireless powering arena for powering small devices implanted in freely behaving rodents. METHODS: We design a cavity resonator based wireless power transfer (WPT) system and utilize our previously developed optimal impedance matching methodology to achieve effective WPT performance for operating sophisticated implantable devices, made with miniature receive coils (<8 mm in diameter), within a large volume (dimensions: 60.96 cm × 60.96 cm × 30 cm). We provide unique cavity design and construction methods which maintains electromagnetic performance of the cavity while promoting its utility as a large animal husbandry environment. In addition, we develop a biaxial receive resonator system to address device orientation insensitivity within the cavity environment. Functionality is demonstrated with chronic experiments involving rats implanted with our custom designed bioelectric recording device. RESULTS: We demonstrate an average powering fidelity of 93.53% over nine recording sessions across nine weeks, indicating nearly continuous device operation for a freely behaving rat within the large cavity resonator space. CONCLUSION: We have developed and demonstrated a cavity resonator based WPT system for long term experiments involving freely behaving small animals. SIGNIFICANCE: This cavity resonator based WPT system offers an effective and simple method for wirelessly powering miniaturized devices implanted in freely moving small animals within the largest space.
Subject(s)
Electric Power Supplies/veterinary , Electroencephalography/instrumentation , Electroencephalography/veterinary , Monitoring, Ambulatory/veterinary , Telemetry/veterinary , Wireless Technology/instrumentation , Animals , Energy Transfer , Equipment Design , Equipment Failure Analysis , Magnetics/instrumentation , Micro-Electrical-Mechanical Systems/instrumentation , Miniaturization , Monitoring, Ambulatory/instrumentation , Telemetry/instrumentation , TransducersABSTRACT
OBJECTIVE: A significant challenge in rehabilitating upper-limb amputees with sophisticated, electric-powered prostheses is sourcing reliable and independent channels of motor control information sufficient to precisely direct multiple degrees of freedom simultaneously. APPROACH: In response to the expressed needs of clinicians, we have developed a miniature, batteryless recording device that utilizes emerging integrated circuit technology and optimal impedance matching for magnetic resonantly coupled (MRC) wireless power transfer to improve the performance and versatility of wireless electrode interfaces with muscle. MAIN RESULTS: In this work we describe the fabrication and performance of a fully wireless and batteryless EMG recording system and use of this system to direct virtual and electric-powered limbs in real-time. The advantage of using MRC to optimize power transfer to a network of wireless devices is exhibited by EMG collected from an array of eight devices placed circumferentially around a human subject's forearm. SIGNIFICANCE: This is a comprehensive, low-cost, and non-proprietary solution that provides unprecedented versatility of configuration to direct myoelectric prostheses without wired connections to the body. The amenability of MRC to varied coil geometries and arrangements has the potential to improve the efficiency and robustness of wireless power transfer links at all levels of upper-limb amputation. Additionally, the wireless recording device's programmable flash memory and selectable features will grant clinicians the unique ability to adapt and personalize the recording system's functional protocol for patient- or algorithm-specific needs.
Subject(s)
Electromyography/instrumentation , Prosthesis Design/methods , Animals , Artificial Limbs , Computer Systems , Electrodes, Implanted , Electronics , Humans , Magnetic Fields , Mice , Mice, Inbred C57BL , Microelectrodes , Reproducibility of Results , Telemetry , Wireless TechnologyABSTRACT
Far-field RF powering is an attractive solution to the challenge of remotely powering devices implanted in living tissue. The purpose of this study is to characterize the peak obtainable power levels in a wireless myoelectric sensor implanted in a patient while maintaining safe local temperature and RF powering conditions. This can serve as a guide for the design of onboard electronics in related medical implants and provide motivation for more efficient power management strategies for implantable integrated circuits. Safe powering conditions and peak received power levels are established using a simplified theoretical analysis and Federal Communications Commission-established limits for radiating antennas. These conditions are subsequently affirmed and improved upon using the finite-element method and temperature modeling in bovine muscle.