MyoWare™Muscle Sensor (AT-04-001) Datasheet by SparkFun Electronics

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MyoWarE I136) |_ Advancer"©[ Technologies a Advancorfi ”away“?
Measuring muscle activation via electric potential, referred to as electromyography (EMG), has
traditionally been used for medical research and diagnosis of neuromuscular disorders. However,
with the advent of ever shrinking yet more powerful microcontrollers and integrated circuits, EMG
circuits and sensors have found their way into prosthetics, robotics and other control systems.
3-lead Muscle / Electromyography
Sensor for Microcontroller Applications
FEATURES
NEW - Wearable Design
NEW - Single Supply
+2.9V to +5.7V
Polarity reversal protection
NEW - Two Output Modes
EMG Envelope
Raw EMG
NEW - Expandable via Shields
NEW - LED Indicators
Specially Designed For Microcontrollers
Adjustable Gain
1 - Power Supply, +Vs
2 - Power Supply, GND
3 - Output Signal, SIG
Sensor Layout
What is electromyography?
EMAIL: support@advancer.co
Raw EMG Signal - 7
Shield Power (output) - 8
GND - 9
www.AdvancerTechnologies.com
© 2015
4 - Mid Muscle Electrode Pin
5 - End Muscle Electrode Pin
6 - Reference Electrode Pin
Reference Electrode Cable
Adjustable Gain
Power Switch
Mid Muscle Electrode Snap
End Muscle Electrode Snap
MyoWareMuscle Sensor (AT-04-001) DATASHEET
APPLICATIONS
Video games
Robotics
Medical Devices
Wearable/Mobile Electronics
Prosthetics/Orthotics
z ‘ x :22 Arduino - m. :22 Arduino - m. BATTERY a© Advancef Technologies
Setup Configurations (Arduino is shown but MyoWare is compatible with most development boards)
a) Battery powered with isolation via no direct external connections
b) Battery powered sensor, Grid powered MCU with output isolation
Isolation
Amplifier
(ISO124)
Note: Isolation amplifier and
battery provide isolation
between user and electrical
grid. IC models are
suggestions only.
Note: Since no component is
connected to electrical grid,
further isolation is not
required. It is also
acceptable to power the
MCU with a battery via the
USB or barrel ports.
EMAIL: support@advancer.co www.AdvancerTechnologies.com
RECOMMENDED
© 2015
(Note: Arduino and batteries not included. Arduino setup is only
an example; sensor will work with numerous other devices.)
and output isolation j Ardulnn Warnin : No isolation. j Ardulnn Advancef Technologies
Setup Configurations (contd)
c) Grid powered with power and output isolation
Note: Isolation amplifier and
power isolator provide
isolation between user and
electrical grid. IC models are
suggestions only.
Isolation
Amplifier
(ISO124)
Power Isolator
(R1SE-0505-R)
d) Grid powered. Warning: No isolation.
Note: This configuration has no
isolation. Usually safe but rare
situations could create a
current loop to the electrical
grid. Not suitable for
commercial applications.
EMAIL: support@advancer.co www.AdvancerTechnologies.com
© 2015
Advancerjg Technologies
Setup Instructions
1) Thoroughly clean the intended area with soap to remove dirt and oil
2) Snap electrodes to the sensors snap connectors
(Note: While you can snap the sensor to the electrodes after they’ve been placed on the muscle, we do not
recommend doing so due to the possibility of excessive force being applied and bruising the skin.)
3) Place the sensor on the desired muscle
a. After determining which muscle group you want to target (e.g. bicep, forearm,
calf), clean the skin thoroughly
b. Place the sensor so one of the connected electrodes is in the middle of the
muscle body. The other electrode should line up in the direction of the muscle
length
c. Peel off the backs of the electrodes to expose the adhesive and apply them to
the skin
d. Place the reference electrode on a bony or nonadjacent muscular part of your
body near the targeted muscle
4) Connect to a development board (e.g. Arduino, RaspberryPi), microcontroller, or ADC
a. See configurations previously shown
Example Sensor Location for Bicep
EMAIL: support@advancer.co www.AdvancerTechnologies.com
© 2015
Note: Not To Scale
Advancerjg Technologies
Why is electrode placement important?
EMAIL: support@advancer.co www.AdvancerTechnologies.com
Raw EMG output
Innervation Zone
Correct Placement
Midline of the muscle belly
between an innervation zone
and a myotendon junction
Midline Offset
Myotendon Junction
Position and orientation of the muscle sensor electrodes has a vast effect on the strength of
the signal. The electrodes should be place in the middle of the muscle body and should be
aligned with the orientation of the muscle fibers. Placing the sensor in other locations will
reduce the strength and quality of the sensors signal due to a reduction of the number of
motor units measured and interference attributed to crosstalk.
© 2015
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RAW EMG vs EMG Envelope
Our Muscle Sensors are designed to be used directly with a microcontroller. Therefore, our
sensors primary output is not a RAW EMG signal but rather an amplified, rectified, and
integrated signal (AKA the EMG’s envelope) that will work well with a microcontrollers
analog-to-digital converter (ADC). This difference is illustrated below using a
representative EMG signal. Note: Actual sensor output not shown.
RAW EMG Signal
Rectified EMG Signal
Rectified & Integrated
EMG Signal
EMAIL: support@advancer.co www.AdvancerTechnologies.com
Reconfigure for Raw EMG Output
This new version has the ability to output an amplified raw EMG signal.
To output the raw EMG signal, simply connect the raw EMG signal pin to your measuring
device instead of the SIG pin.
Connect
© 2015
Note: This output is centered about an offset
voltage of +Vs/2, see above. It is important
to ensure +Vs is the max voltage of the
MCU’s analog to digital converter. This will
assure that you completely see both positive
and negative portions of the waveform.
Gain -- IIIIE Advancef Technologies
Connecting external electrode cables
Ref
End
Middle
EMAIL: support@advancer.co www.AdvancerTechnologies.com
© 2015
This new version has embedded electrode
snaps right on the sensor board itself,
replacing the need for a cable. However, if
the on board snaps do not fit a users
specific application, an external cable can
be connected to the board through three
through hole pads shown above.
Middle
Connect this pad to the cable leading to an
electrode placed in the middle of the muscle body.
End
Connect this to the cable leading to an electrode
placed adjacent to the middle electrode towards
the end of the muscle body.
Ref
Connect this to the reference electrode. The
reference electrode should be placed on an
separate section of the body, such as the bony
portion of the elbow or a nonadjacent muscle
Adjusting the gain
We recommend for users to get their sensor setup working reliably prior to adjusting the
gain. The default gain setting should be appropriate for most applications.
To adjust the gain, locate the gain potentiometer in the lower left corner of the sensor
(marked as “GAIN”). Using a Phillips screwdriver, turn the potentiometer counterclockwise
to increase the output gain; turn the potentiometer clockwise to reduce the gain.
Note: In order to reduce the required voltage for the
sensor, the redesign switch out a JFET amplifier for a
CMOS amplifier. However CMOS amplifiers tend to have
slower recovery times when saturated. Therefore, we
advise users to adjust the gain such that the output signal
will not saturate the amplifier.
2x 0.'125 DIA. Thm H | Advancer"©[ Technologies
Electrical Specifications
Parameter
Min TYP Max
Supply Voltage +2.9V +3.3V or +5V +5.7V
Adjustable Gain Potentiometer 0.01 Ω50 kΩ100 kΩ
Output Signal Voltage
EMG Envelope
Raw EMG (centered about +Vs/2)
0V
0V
--
--
+Vs
+Vs
Input Impedance -- 110 GΩ--
Supply Current -- 9 mA 14 mA
Common Mode Rejection Ratio (CMRR) -- 110 --
Input Bias -- 1 pA --
EMAIL: support@advancer.co www.AdvancerTechnologies.com
Dimensions
© 2015
0.82
(20.7)
2.06 (52.3)
2 x 0.125 DIA. Thru Hole
1.75 / (44.4)
0.019
(5.0)
1.93 / (49.1)
0.51
(13.0)

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