Research
Our interdisciplinary research approach brings together multiple disciplines spanning neuroscience, electronics, bioengineering, electromagnetics, and integrated circuits. We focus on the convergence of engineering and medicine and pursue major technological and scientific breakthroughs in neuroprosthetics. Some examples of our research areas include implantable electronic systems, multi-scale neuromodeling and implantable system modeling, and high-efficiency, application-specific wireless power and data telemetry.
Research Areas
Multiscale Modeling of Neural Systems
Our group has developed a modular computational framework for multiscale modeling of neural systms that integrates in space and time: (1)an admittance/impedance (AM/IM) multiresolution method capable of predicting currents induced in microscale models of nerves due to neurostimulators of arbitrary geometry with (2) a neural simulation environment (NEURON) capable of predicting nerve excitation.
Wireless Powering of Medical Devices and Antennas
Biomedical implants are important electrical devices for health monitoring, treatment of disease, and prosthetics. Wireless Power Transfer (WPT) systems enable physicians and patients to avoid repeated surgeries to replace/recharge the power supply of these implants and remove the need for bulky implantable batteries for power. In addition, WPT allows for wireless data transfer and device programming, thus making biomedical implants more practical. Therefore, optimal design of WPT systems is crucial for the reliable and safe operation of implantable devices and therefore the health of patients.
Specific Absorption Rate testing
Specific Absorption Rate (SAR) is a measure of the amount of RF energy absorbed in the human body due to a radiofrequency (RF) device such as a cell phone or medical implant with wireless power or telemetry. For safety, the FCC, along with other international organizations, limits the amount of exposure from such devices. In the case of the FCC, exposure is limited to a level of 1.6 watts per kilogram (1.6 W/kg), which is a measure of the local RF power (in watts) deposited to a standardized mass of tissue (in kilograms). In order to certify that a device is operating safely within the regulatory limits, both numerical and experimental studies should be performed.
Retinal Prosthesis
Most progressive vision loss occurs when the first layer of the retina (the photoreceptors) is damaged. Retinal prostheses aim to restore vision by bypassing the damaged photoreceptors and directly stimulating the remaining healthy neurons. Our approach uses novel technologies to reduce area and power, and to support hundreds of channels to restore functional visual perception with small implants.
Hippocampal Prosthesis
The hippocampus is responsible for the formation of new long-term declarative memories: the formation of mnemonic labels that identify a collection of features and form relations between multiple collections of features. It is the degeneration and malformation of hippocampal neurons that causes the memory disorders associated with stroke, epilepsy, dementia, and Alzheimer’s.
Neural Interfaces
Neural interfaces directly interact with neurons in our body. Neural recordings of brain activity are one of the key elements for studying the brain, which has led to remarkable breakthroughs in science, engineering and medicine. Similarly, neural stimulation of key brain regions has enabled treatment of medical conditions such as Parkinson’s disease, epilepsy, and others.
Currently approved neural interface devices have limited bandwidth and spatial coverage of the brain, with up to tens or hundreds of channels in the system. The majority of these channels are dedicated to recording and only a few to stimulation. Future high-density, high-bandwidth bidirectional neural interface systems will support thousands of channels for simultaneous recording and stimulation, and could provide real-time visualization of multiple brain-regions with high temporal and spatial resolution.
Integrated Circuits for Neuroprosthetics
Integrated circuits are essential for the development of advance prosthetics and miniaturization of medical systems. They need to be small and consume very low power while performing important tasks such as signal acquisition and conditioning, signal processing, on-chip computation, wireless communication, and neuromodulation.
We focus on developing new circuit-level, system-level, and integration-level techniques for the design of novel neuroprosthetics. Our approach uses analog, mixed-signal, and radio-frequency techniques, and integrates advanced materials, devices, and biological and chemical sensors and actuators.