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!

Low-Power Head-Mounted
Deep Brain Stimulator

The Deep Brain Stimulation (DBS) therapy involves implantation of small electrodes in deep brain structures, connected to a pulse generator, which is so bulky that it should to be implanted in the upper chest wall and wired subcutaneously to the electrode contacts emerging from the top of the head. According to several studies the subcutaneous extension wires and their connectors are a source of morbidity for patients and the primary cause of mechanical failure in DBS implants.

The main objective of this research is to develop a significantly smaller, more efficient, integrated microstimulator that can be practically attached to the head at the point of electrode entry to the brain. Existing DBS circuits can only control the pulse width, frequency, and either voltage or current amplitude. Voltage-controlled stimulation (VCS) provides greater power-efficiency but it can only be used when the electrodenand tissue impedances are well known. Current-controlled stimulation (CCS) is safer and provides more control over the stimulus parameters, but it consumes more power. Today’s DBS implants, which have inherited the heart pacemaker technology, are VCS-based and manufacturers have to indicate the safety limits by providing tables in terms of the electrode/tissue impedance, pulse width, and pulse amplitude.

DBS Prototype Board: This wirelessly controlled DBS prototype can generate three types of stimulus pulses based on VCS, CCS, and SCS stimulation strategies. This system can accurately measure the amount of charge injected into the tissue.

We have designed novel switched-capacitor based stimulation (SCS) circuitry that directly controls the amount of injected charge into the neural tissue. This is accomplished by generating charge-controlled, exponentially decaying bursts of stimulus pulses. The SCS circuit combines the power efficiency of the VCS circuits with the safety and stimulation parameter controllability of the CCS circuits. This innovative technique is expected to substantially simplify the pulse generator architecture and reduce its size and power requirements.

As part of this research we use Finite Element Analysis (FEA) to explore the impact of microstimulating arrays on biological tissue and distribution of current as a function of electrodes geometry, configuration, and stimulus waveforms. Techniques to determine the electric field, potential, current densities, and heat distributions are used to determine the feasibility and efficacy of an electrode design. Using these 3-Dimensional models, alternative layouts and electrode designs can be evaluated prior to prototyping. Further, these models can be applied to several different types of electrodes including cortical, cochlear, and retinal in addition to deep-brain stimulating electrodes.

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