This sensor will measure the filtered and rectified electrical activity of a muscle; outputting 0-Vs Volts depending the amount of activity in the selected muscle, where Vs signifies the voltage of the power source.
Advancer Technologies started a Kickstarter campaign to produce an updated version of their Muscle Sensor v3 board. The MyoWare™ Muscle Sensor (AT-04-001) is the latest electromyography (EMG) sensor from Advancer Technologies. Here is an overview of the MyoWare product line and how to use it.
Figure 1. MyoWare main sensor board
- Single supply - MyoWare won't need +/- voltage power supplies! Unlike our previous sensor, it can now be plugged directly into 3.3V through 5V development boards.
- Embedded Electrode Connector - Electrodes now snap directly to MyoWare, getting rid of those pesky cables and making the MyoWare wearable!
- RAW EMG Output- A popular request from grad students, the MyoWare now has a secondary output of the RAW EMG waveform.
- Polarity Protected Power Pins - To add some protection so the sensor chips don't burn out when the power is accidentally connected backwards.
- ON/OFF Switch - Speaking of burning out the board, we've also added an on-board power switch so you can test your power connections more easily.
- LED Indicators - We've added two on-board LEDs one to let you know when the MyoWare's power is on and the other will brighten when your muscle flexes.
To solder the header pins to the MyoWare shields, you’ll need to do some soldering. Soldering tools (including an ironand solder) are a must for any electronics workbench. While not required, the Break Away Headers - 40-pin Male (Long Centered, PTH, 0.1") and a breadboard can be useful to help in soldering female header pins to the shields. The 1x3 straight breakaway headers included in the MyoWare Muscle Sensor Kit can also be used to help solder. Just make sure to insert the longer end of the header into a breadboard to secure the pins.
For more information, please have a look at the official MyoWare Muscle Sensor datasheet.
In the image below, the left most electrode connection should be connected to the muscle being measured. This is equivalent to using the red insulated conductor on the cable. The mid muscle electrode on the right breaks out on the black snap. The reference electrode has continuity with the blue snap on the cable.
MyoWare sensor layout
As shown in the image above, there are three rows of three 0.1" spaced plated through holes. On the right is the power supply +Vs, & ground, along with the processed output signal (holes 1, 2, & 3).
Along the long edge near the mid muscle electrode snap are the thru-holes for remote electrode connection (holes 4, 5, & 6).
On the opposite end are three ‘outputs’. Hole 7 is the raw, unprocessed EMG signal. Hole 8 is the switched power. Power goes into the board via hole 1, is switched, and comes back out hole 8 ( if you believe in passive sign convention (PSC) ). Hole 9 is the ground reference for the switched power.
The shields come with assorted support for these pins. Some shields such as the Power Shield don’t support the remote connections. If you need access to these pins the boards that use or can pass them through must go lower in the stack. Both the Cable Shield and the Proto Shield have this connection capability.