EEG Biofeedback Final Report Adrian Smith, gte198f Daniel Shinn, gte539f Ken Grove, gte262f ECE Group N1 April 23, 2002

2 What is an EEG? l EEG stands for electroencephalogram l EEG signals are created by measuring the difference in electrical currents across neuron membranes l Electrodes attached to the body pick up these signals l There can be a only a few electrodes or many attached to the head

3 EEG signals l Many naturally occurring signals in the human body effect EEG signals l Frequency Analysis helps to separate the different signals

4 Types of EEG signals l EEG signals have been classified into 4 categories: ÄDelta0.3 to 4 Hz uDreamless sleep ÄTheta4 to 8 Hz uAssociated with thoughts which produce dreams ÄAlpha8 to 13 Hz uResult of unfocused thoughts ÄBetaabove 13 Hz uResult of interactions with environment

5 Electrode placement l Electrode placement can effect signals received

6 Related Research l Creating a Brain Computer Interface (BCI) has been a goal for researchers since computers were first introduced l BCI’s could help patients with motor disabilities use computers or mobility platforms l What is necessary: ÄAmplification ÄFiltering ÄClassification ÄControl

7 Related Research (cont.) l Large programs researching BCI’s: ÄWadsworth Center in Albany ÄGraz University of Technology in Austria l Problems facing the programs: ÄData transfer rate ÄEfficiency ÄDifferences between test subjects ÄLearning curve for new users

8 Previous Semesters Work l Produced an amplifier that can output a strong enough signal to process with an Analog to Digital Converter l Created a baseline for our work with the amplifier and EEG signals

9 Our Focus l Purchase components needed to replicate the amplifier board l Assemble our amplifier board l Purchase and install an ADC board that can remain with the class for use in future semesters l Digitize the output signal l Interpret signals as commands for controlling a remote control vehicle l Output control commands to remote control vehicle

10 Design Block Diagram

11 Amplifier Board l Built in previous semester l Based on Thomas Collura’s design, founder of Brainmaster l Two stage amplifier l 7805 voltage regulator power supply ÄCan use 9V battery or 6V-35V DC power supply

12 Amplifier Schematic

13 Amplifier Design Stage 1 l Gain of 50 l Common Mode Rejection Ratio l Provides noise reduction and signal centering Stage 2 l Gain of 390 l Capacitors stabilize power supply

14 Amplifier Parts List Resistors: l (1) 10K 1/4W 5% l (2) 1K 1/4W 5% l (3) 130K 1/4W 5% l (2) 200K 1/4W 5% l (2) 10M 1/4W 5% l (2) 200K 1/4W 5% l (1) 51K 1/4W 5% Integrated Circuits: l (3) OP-90 amplifiers l (1) 620AN amplifier l (1) LM7805C voltage regulator Capacitors: l (1) 0.47uF 400V polypropylene (P474J) l (3) 0.1uF 400V polypropylene (P104J) l (2) 0.001uF 400V polypropylene (P103J) l (1) 10uF 6.3VDC Tantalum Other: l (1) Set of 3 conductor signal leads

15 Analog-Digital Converter l Current board is a Keithley DAS-1701ST l Installed in borrowed computer l Must be moved but face PCI interface problem l Keithley KPCI-1307 card is the proposed solution

16 Keithley KPCI-1307 l 100k samples/sec l 16 single ended or 8 differential inputs l AutoZero capability filters out drift l 32 digital I/O l 3 clock/timer l drivers included l VHDL program or DriverLINX software options l Price : $680

17 VHDL Implementation l Download code to Flex10k20 chip on Altera board l Board receives signals from the KPCI-1307 and controls mechanical devices

18 DriverLINX Implementation l Create DLLs for data acquisition and signal routing l Interface can be programmed in ÄC ÄC++ ÄVisual Basic ÄActive X

19 Overview of Completed Objectives l EEG Amplifier ÄOrder parts ÄAssembly ÄTesting l Data Acquisition Board ÄOrder board ÄInstallation of board ÄInstallation of drivers and software

20 EEG Amplifier (Parts) l Resistors: (1) 10K 1/4W 5% (2) 1K 1/4W 5% (3) 130K 1/4W 5% (2) 200K 1/4W 5% (2) 10M 1/4W 5% (2) 200K 1/4W 5% (1) 51K 1/4W 5% l Capacitors: (1) 0.47uF polypropylene (P474J) [$1.62] (3) 0.1uF polypropylene (P104J) [$0.74] (2) 0.001uF polypropylene (P103J) [$0.45] (1) 10uF 6.3VDC Tantalum [$0.52] l Integrated Circuits: (3) OP-90 amplifiers [$2.35] (DIP package was not available when placing orders so SOIC package was substituted with the use of an 8-pin SOIC to DIP adapter. Price reflects cost of DIP package, as this should be ordered in future semesters.) (1) 620AN amplifier [$5.92] (1) LM7805C voltage regulator [$0.43] l Other: (1) Set of 3 conductor signal leads [$14.40] (3) Disposable electrodes for each testing session [$0.24] (1) Pre-holed circuit board [$8.49]

21 EEG Amp – Assembly and Testing EEG Amp Fully Assembled Group N1’s Lab Rat

22 Data Acquisition Board - Installation l KPCI-3107 Ä 16 analog single-ended or 8 analog differential. Ä 32 digital outputs Ä PCI interface l CAB-1284CC-2 l STP-36

23 KPCI-3107 (DriverLINX software) l Real-time data acquisition (with test panels) l Analog/Digital I/O programming Ä uses C++, VB, and Active X l Real-time Triggering via driver Ä allows user to specify trigger voltage and action to take after device is triggered.

24 Final Testing Waveforms AIO Test Panel with Sine Wave input to Channel A l The test panel allowed for verification that the acquisition board was functioning correctly l Eyebrow and eye blinks were recorded and graphed using the A/D board.

25 Final Testing Waveforms

26 Board at End of Semester – A/D Board Amplifier connected to A/D board with electrodes A/D board connected to Computer

27 Ideas for Continuing the Project l Build a low-noise case for STP-36 break-out boards. l Calibrate gain for the EEG Amp input signal into an analog differential input channel. l Research and learn how to use programming knowledge into a DriverLINX program. l Program driver for KPCI-3107 board to output needed digital signal.