Integrated Electroencephalography and Transcranial Direct Current Stimulation Device

Matthew Gray, Aaron Sears and Savannah DewberryUniversity of Alabama at BirminghamClient: Dr. Franklin Amthor

Background: EEG and tDCS● Electroencephalogram (EEG)

○ Measurement of electrical activity in brain

○ Surface electrodes placed on scalp

○ Freq: 1-100 Hz

● Transcranial Direct Current Stimulation (tDCS)

○ DC Current applied to the brain through electrodes

○ Modulates cortical excitability

Higgins (2008)EEG 10/20 Electrode Placement Diagram

Clients• Dr. Franklin Amthor

• Interim Director of Behavioral Neuroscience Graduate Program

• PhD. Biomedical Engineering• Original idea for simultaneous, same-site

recording during tDCS stimulation

• Dr. Mary Boggiano• Associate Professor of Psychology• Studying effects tDCS on cravings• Currently using TCT tDCS Stimulation Kit

• tDCS Only• Behavioral Feedback

Dr. Amthor Dr. Boggiano

Design Need • Transcranial Direct Current Stimulation (tDCS)

• Possible treatment for many various neurological conditions • Depression• Anxiety• Binge-eating

• Physiological effect with respect to neurological conditions not well understood

• Current pharmaceutical treatment isn’t always effective and has many unwanted side effects

Picture?

TCT tDCS Transcranial Stimulation Kit - $349

Existing Solutions• StarStim Neuro Electrics: $10,000+

• Research-class multichannel transcranial current stimulator

• EEG and accelerometry• Contains simultaneous EEG recording during

tDCS.

• Soterix Medical tDCS: $4,500+• Simple Interface• Out-source EEG capability Soterix tDCS

Starstim Neuroelectrics

Device Novelty • Our device goals:

• Provides same-site, simultaneous electroencephalography (EEG) and transcranial Direct Current Stimulation (tDCS)

• Reasonably cheap (<$1000)• EEG Addon capability for TCT tDCS device

• Targeted Users:• Researchers conducting clinical studies

Constraints

Component CostsPart Cost

Arduino Uno $24.95

Electrodes + sponge sleeves $32.27

ADC – ADS1015 $9.95

Ethernet cable $5.89

Operational amplifiers $0.94

Instrumentational Amplifier $20.74

Resistor Kit $7.99

TCT TDCS $349.00

Total $451.73

Overall Device

Data Acquisition Subsystem - Arduino• Switch • Converter - ADS1015• Voltage Offset Circuit• The Arduino has

dedicated SCL (clock) and SDA (data) connections

EEG Subsystem - Circuit DesignStage 1:Filter: 1 Hz High-Pass

Stage 3:Gain: 161xFilters: 1Hz-100Hz Bandpass

Stage 4:Filter: 60Hz Notch

Stage 5:Buffer

Inpu

t

Out

put

Grounding

Stage 2:Instrumentation AmplifierGain: 206.8x

Validation• Comparison

between signals acquired with a commercial EEG (Grass) device and our circuit

Figure 2: PSD plot of signal acquired with Grass EEG machine (right) and our (NeuroVolt) EEG circuit (left).

Figure 1: Raw EEG signal acquired from NeuroVolt EEG circuit (red) and Grass 7D Polygraph (white).

Future Work

• tDCS voltage changes with perspiration, movement, etc. & causes change in voltage.• Some AC Noise from 1 to 18 Hz

• Project is being further developed by Dr. Amthor’s lab for use in Dr. Boggiano’s lab

Figure 3: PCB Layout for our EEG circuit w/ AC Coupling

Acknowledgements• Dr. Amthor• Dr. Boggiano• Dr. Eberhardt• Dr. Dobbs• Mary Katherine Osborne• Carl Stephens

• NIH, NSF, and VentureWell grants