EEG and EMG:

basics and application第二組

電機三 耿正達

電機三 溫俐盛

電機三廖宜倫

All the signals we record

The signals’ amplitude and speed in all the body are

always 55mv 左右

Variation in frequency

Human body is electrically neutral, different

concentration

Membrane potential Voltage

More intense, faster

frequency Crash course

Resting Neuron Potential -70mv

Positive Ions and negatively charged Proteins

Polarized!

Sodium – Potassium pump

• Voltage Gated Channels

(Na+ opens at -55mV)

• Ligand-Gated Channels

(Neurotransmitters)

• Mechanical Channels

(Moves) Crash course

Current

Due exchange of Ions

Chain Reaction

During the process it

CANNOT respond to any

other stimulus

Refractory period

• Can vary by conduction speed!

• Myelined axons

• Nodes de Ranvier

• Saltatory conduction

Crash course

Crash course

Interneuronal communication

Synapses! junction

100 billion neurons

1 neuron from 1,000 to 10,000 synapses

Electric communication Group text everybody gets the signal

Chemical communication Private message

CONTROL

Signal processors

Neurotransmitters can excite (+) or inhibit (-) the cell

The waves we measure are the sum of all this synapses and axons.

Crash course

腦電訊號產生原理

Pyramidal neurons(錐體神經元) in the most superficial

layers of the brain and spatially aligned

腦電訊號產生原理

When positive ions rush into the cell, the extracellular

space becomes negatively charged(orange)

In a distant part, ions leave the cell, and

this outward flow of positive ions

leaves extracellular space positively charged

(blue)

Forms an electrical dipole

Summation of all dipoles -> EEG

Brain waves

Divided by frequency

Greater the impulse, greater

the frequency

examinedexistence

Neuromuscular junction

When the action potential reaches the nerve

end, acetylcholine is released. triggers

action potential in the muscle fiber

Action potential reaches T-tubules stimulates

release of Ca2+ ions from sarcoplasmic

reticulum Ca2+ ions trigger movement of the

myosin contraction

Contraction stops when there are no more Ca2+

ions

Probes

Electrodes Ag-AgCl

“Ionic currents in the body into electronic currents in

the probe” (bioexplorer)

They have to be nonpolarizable

Bioexplorer

Bioexplorer

An improved Probe

Contains a pressure compensator for it to

erase the DC currents due the augment on

the contact area. Such a signal is integrated

by the computation unit.

hyperphysics

• The characteristic resistance of the skin varies from about 100K to 1 MΩ.

Bioexplorer

量測EEG

將電極使用導電膠固定在頭皮上

10 20 system electrode placement

量測EEG

The numbers: the distance from certain

reference points on the head to ensure

the placement is consistent.

將頭頂使用尺規作測量，

再依照比例在頭皮上做上記號

可達到地區上的等分，間距相當，

並覆蓋全腦

Electrode-> Differential amplifier

Applications of EEG

EEG應用

不同的認知活動，大腦各區位有不同的活動

EEG即時訊號

異常腦部活動

腦機介面

EEG應用-催眠

被催眠對象若有被真正催眠，β腦波會減少

EEG應用-腦機介面

提取腦波特徵，控制機器

不需經由周邊神經和肌肉就能讓大腦與外界溝通的系統

腦波電話

動作想像訊號

EEG應用

NeuroSky

Necomimi

EEG應用

Emotiv

多電極偵測EEG

動作指令

EEG應用-生物辨識

Use EEG signals to identify individuals

Use an EEG system with 30 electrodes and present a person

with a series of images

Use ERP(event related potential)(the way their brains respond

to images)

Hard to be hacked:

train a hacker’s brain to mimic the right responses

Applications of EMG

General classification

Gait and posture

Sports and arts

Gynaecology

Oral and facial function

Generally used

as diagnostic

tools

Gait and posture

Exoskeleton robots

mechanical

constructions attached

to human body parts

enhancing human

motion

Fleischer, Wege, Kondak and Hommel. “Application of

EMG signals for controlling exoskeleton robots”

Exoskeleton robots

Design incorporates: human as control + strength of exoskeleton

Suitable for army and first aid – carry heavy load

Exoskeleton robots can be implemented in different ways:

1. Force sensors – detect discrepancies between desired motion and the exoskeleton motion

delay problems

exoskeleton in contact with the environment difficult to separate the measured force signal from the subject and from the environment

2. EMG signals – can be analysed to predict human motion – reduce the delay

Exoskeleton robots

Placement of electrodes

Raw signals processed as RMS values

Exoskeleton robots

Mechanical structure

Gait and posture

Prosthetics

• Cosmetic

• Body powered –

don’t require any

power supply, very

uncomfortable to

operate

• Myoelectric – uses

EMG signals

Prosthetics

Bebionic

http://bebionic.com

Prosthetics

Bebionic – uses surface EMG, not intramuscular – non-

invasive

https://www.youtube.com/watch?v=_qUPnnROxvY

Prosthetics

General structure

Gynaecology

Uterine myography

Only occasional, low amplitude bursts during

most of the pregnancy

More frequent and higher amplitude during

labor

Better choice to diagnose labor than other

methods – more accurate (intrauterine

pressure catheters, fetal fibronectin,

cervical length measurement and digital

cervical examination)

Lucovnik et al, 2011. “Use of uterine

electromyography to diagnose term and preterm

labor”

Reference Crash Course

https://www.youtube.com/watch?annotation_id=annotation_3256407049&feature=iv&src_vid=OZG8M_ldA1M&v=VitFvNvRIIY

https://www.youtube.com/watch?v=OZG8M_ldA1M&t=10s

Hyperphysics

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html

Bioexplorer

http://www.bioexplorer.it/Data/Sites/1/Docs/A%20bioelectrical%20sensor%20for%20the%20detection%20of%20small%20biological%2

0currents.pdf

NCBI

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2386953/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2386953/table/T1/

http://examinedexistence.com/5-different-brainwave-frequencies-mean/

Reference

Application of EMG

http://bebionic.com

https://www.youtube.com/watch?v=_qUPnnROxvY

http://bebionic.com/distributor/documents/bebionic3_Tech_Manual_web.pdf

Fleischer, Wege, Kondak and Hommel. “Application of EMG signals for controlling exoskeleton robots”

Gopura, Kiguchi. “Application of Surface Electromyographic Signals to control Exoskeleton Robots”

Talbot, 2014. “Using Arduino to Design a Myoelectric Prosthetic” (Honors Thesis)

Lucovnik et al, 2011. “Use of uterine electromyography to diagnose term and preterm labor”

Vrhovec and Lebar. “An Uterine Electromyographic Activity as a Measure of Labor Progression”

Reference Applications of EEG

https://investigatortw.wordpress.com/2014/07/06/%E8%85%A6%E6%A9%9F%E4%BB%8B%E9%9D%A2-brain-computer-interface-%E5%B0%88%E9%A1%8C-%E4%B8%8A/

http://www.ckwang.com.tw/pdf/mentally/n-mentally-01.pdf

https://www.youtube.com/watch?v=8a5X5ABgBnU

https://www.youtube.com/watch?v=86zIa3pGM50

http://newsletter.teldap.tw/news/InsightReportContent.php?nid=6121&lid=706

https://investigatortw.wordpress.com/2014/07/13/%E8%85%A6%E6%A9%9F%E4%BB%8B%E9%9D%A2-brain-computer-interface-%E5%B0%88%E9%A1%8C-%E4%B8%8B/

http://mic.iii.org.tw/aisp/reports/reportdetail_register.asp?docid=3024&rtype=freereport

http://spectrum.ieee.org/the-human-os/biomedical/devices/logging-into-your-devices-with-your-mind

http://spectrum.ieee.org/biomedical/devices/brainprint-biometric-id-hits-100-accuracy

Thanks for your attentionQ&A