March 2017

Byunghun successfully defended his thesis and graduated from GT-Bionics as a PhD student. Congratulations, Dr. Byunghun Lee!

Congratulation to Daniel Canales for receiving the ECE Undergraduate Research Award!

Jaemyung successfully defended his thesis and graduated from GT-Bionics as a PhD student. Congratulations, Dr. Jaemyung Lim!

February 2017

Dr. Ghovanloo has been awarded promotion to Full Professor. Congratulations! Please see the story here.

September 2016

GT just released story about our EnerCage project!

Dr. Ghovanloo will give a talk on 8th Seminar on Electronics and Advanced Design with title "Implantable and wearable microelectronic device to improve quality of life for people with disabilities".

August 2016

We have two papers at EMBC'16.

Temi successfully defended her thesis and graduated from GT-Bionics as a PhD student. Congratulations, Dr. Temi Prioleau!

June 2016

Temi received Chi Foundation award. Congratulations Temi!

Multi-Carrier Wireless Link for Implantable Biomedical Devices

An inductive link between two magnetically-coupled coils that constitute a transformer is the most common method to wirelessly transmit power and data to implantable biomedical devices that have relatively high power consumption such as neuromuscular stimulators, cochlear implants, and visual prostheses. Neuroprostheses that substitute sensory functions also need sizeable amounts of real-time data to interface with a large number of neurons by means of tens to hundreds of stimulating sites that are driven simultaneously through multiple parallel channels. The wireless link should be robust enough not to be affected by patient’s motion artifacts or minor coils misalignments. A back telemetry link is also needed for implant power regulation, stimulating sites impedance measurement, and recording the neural response for accurate electrode placement and stimulation parameter adjustments.

Therefore, high power transmission efficiency, high data transmission bandwidth, magnetic coupling insensitivity, and back telemetry are the major wireless link requirements in the design and implementation of high performance implantable biomedical devices. While these requirements are individually attainable, they have not been achieved concurrently with traditional techniques. The reason is that there are conflicting constraints involved in achieving high performance in two or more of the above system requirements.

The wireless link operating frequency, also known as the carrier frequency, is one of the most important parameters of an inductive link, which affects all other system specifications. Traditionally, a single carrier frequency has been used for (1) inductive power transmission, (2) forward data transmission from outside to the implanted device, and (3) back telemetry from the implanted device outward. In this research we are using three carrier signals at three different frequencies and amplitude levels: (a) low-frequency high-amplitude (fP < 1MHz) for power transmission, (b) medium-frequency medium-amplitude (fFD ~ 50MHz) for forward data link, and (c) high-frequency low-amplitude (fBT > 400MHz) for back telemetry. These frequencies are optimal for the above three major functions and we can effectively isolate many of the competing parameters in the design of a wireless link. Therefore, we expect to achieve a high performance in all of the aforementioned system requirements.

The research presented here is aimed at developing a robust, power-efficient, wideband, bidirectional wireless link using multiple carrier frequencies. The new link will be utilized in development of a prototype neuroprosthetic testbed for a visual prosthesis. The prototype neuroprosthesis will be tested in vitro to evaluate the multi-frequency wireless link performance in the tissue environment. Then it will be used in short term in vivo experiments.

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