A study on the effect of age, gender and paralysis
on sEMG signals
What is sEMG?
• sEMG: Surface Electromyography
Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles.
What is electrical activity of muscles?
• Muscles are stimulated by signals from nerve cells called motor neurons. This stimulation causes electrical activity in the muscle, which in turn causes contraction. These signals are called myoelectric signals.
Myoelectric signal
• Frequency Range: 10 Hz to 500 Hz
• Amplitude: 10uV to 5000uV
What is electrical activity of muscles?
Myoelectric signal
• Frequency Range: 10 Hz to 500 Hz
• Amplitude: 10uV to 5000uV
What is electrical activity of muscles?
NOISE
What is electrical activity of muscles?
Power Transmission Lines(Hum)
India: 50Hz
USA: 60 Hz
Difficulties for retrieving the signal.
• Low amplitude.• Low SNR.• Highly immune to noise.
• High gain amplifier.• High CMRR• Filter: 50hz band stop and
10 hz-500Hz bandpass.
Requirement:
• Low amplitude.• Low SNR.• Highly immune to noise.
Hardware:
Instrumentation amplifier(AD620)
Gain Range: 1:10,000
CMRR= 120dB
G = 49.4kΩ/ Ro+1
sEMG sensor(Electromyograph)
Electrodes:
• Dry electrodes:
Positioning of electrode:•Electrode 1 and electrode 2 across the target muscle i.e. Flexor carpi radialis.•Electrode 3 to the body ground.
Electrodes:
Positioning of electrode:•Electrode 1 and electrode 2 across the target muscle i.e. Flexor carpi radialis.•Electrode 3 to the body ground.
Electrodes:
Data acquisition:
Data acquisition:
Processing
• Now we have 16-bit data in MATLAB.
16 bit data(Time Domain)
DFT
Data in frequency
DomainFilter
implementation
Processing
• Now we have 16-bit data in MATLAB.
16 bit data(Time Domain)
DFT
Data in frequency
DomainFilter
implementation
Processing
• Now we have 16-bit data in MATLAB.
16 bit data(Time Domain)
DFT
Data in frequency
DomainFilter
implementationData Analysis
Volunteers
No. of Volunteers Age Group Gender Normal/Paralytic
10 16-25 M Normal
10 16-25 F Normal
5 35-45 M Normal
5 55-65 M Normal
5 55-65 F Normal
1 35-45 F Half-Paralytic
• In total 36 volunteers were employed.
• Protocol followed:• Sensors were attached to the volunteers’ right
arm and they were asked to keep their arm in fully relaxed position.
• Then they were asked to keep there arm in fully excited position by tightening their fist to get the maximum firing by the muscle neurons.
• Similar task was done with the left arm.
Volunteers
Data Analysis and interpretation
Left hand sEMG data for age group 16-25.
Data Analysis and interpretation
Right hand sEMG data for age group 16-25.
Data Analysis and interpretation
Right and Left hand sEMG data for male of age group 55-65..
Data Analysis and interpretation
Right and Left hand sEMG data for female of age group 55-65..
Data Analysis and interpretation
Comparison between the left hand sEMG data of different age groups at fully excited position.
Data Analysis and interpretation
Comparison between the sEMG data of the normal hand to the paralytic hand of a half paralytic individual of age group 35-45.
Result
• Right hand’s sEMG signal in all the age group is more in comparison to that of the left hand.
• sEMG data of female is found to be less than in comparison to the male, in all age groups.
• sEMG signal’s strength increases from age group (16-25) to age group (35-45) and then decreases for age group (55-65).
• The paralytic hand shows less amplitude sEMG signals in comparison to the normal hand of the same individual
Future aspects
• This study and data acquired during the experiment can be used as a reference to study the electric activity of Flexor carpi radialis for different movement of hand.
• Database of electrical activity of major muscles of human body can be made, which can be used to create the prosthetic limbs for people with paralysis or amputees.
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