This article provides everything you need to know to start recording data with your biosignalsplux Electromyography (EMG) sensor.
The EMG sensor is compatible with all biosignalsplux acquisition systems. While the setup used in the examples below is based on an 8-channel biosignalsplux hub, the configuration of your EMG sensor is equal for all other systems.
Connecting Your Sensor
Your biosignalsplux system consists of 5 to 10 ports, of which 4 to 8 are reserved for sensors and the remaining for auxiliary uses.
Connect your EMG sensors to any of the numbered ports (green). For best signal acquisition results, we recommend the use of an additional reference cable, which should be connected to the port with the downwards pointing arrow under port 4 of your device (yellow).
Placing Your Electrodes
EMG signals are usually measured using a bipolar setup which means that two measuring electrodes with a positive (IN+) and a negative (IN-) lead are placed on the muscle of interest to measure the voltage differences with respect to a baseline (see reference electrode info further below).
For ensuring the best conditions for high-quality signal acquisitions we recommend the following steps for your electrode placement:
- Skin Preparation: Follow our Skin Preparation Tutorial to ensure best skin conditions for EMG acquisitions
- Electrodes: Ensure that you are using a new pair of electrodes when using disposable electrodes or to properly clean your reusable electrodes before use
- Measuring Electrodes Placement: Please the electrodes along the muscle fibre and on the muscle hill, with the electrodes being approx. 2 cm apart from each other
- Reference Electrode: The reference electrode must be placed in a region of low muscular activity, optimally on a bone such as the elbow or the clavicle
The example below shows how to place the electrodes to measure the muscle activity of the biceps brachii. The electrode positioning shows the two measuring electrodes placed on the muscle and the reference electrode on the bone (elbow).
The EMG sensor’s electrode cables come with two colored sleeves to mark the positive (red sleeve) and the negative (black sleeve). The electrodes can be positioned in either way but along the muscle fibre and on the muscle belly.
We also recommend consulting the SENIAM Guidelines on EMG electrode placements, which provide user information on electrode and placement recommendations for a variety of different muscles.
Setting Up OpenSignals
This setup is compatible with our OpenSignals software which you can download for free.
To setup your device and sensor, enter the OpenSignals device manager by clicking on the icon highlighted below.
Click on the device panel of your device (make sure your device is turned on) and click on the READ SENSORS icon to setup your device. After a few seconds, your sensor should be listed in the device panel with the channel port matching the port to which you connected your sensor to the biosignalsplux hub.
Activate your device for acquisition by ensure that the ENABLED button is blue (click on it if it is in grey).
Frequently Asked Questions (FAQs)
Do I need to use the reference cable?
Although acquisitions are possible without the reference cable, the quality of the data without the use of this cable can be compromised, reason for which we recommend the use of the cable for acquiring accurate and reliable signals.
What electrodes can I use the sensor with?
If you are inexperienced with signal acquisitions, we recommend starting off with the disposable electrodes due to their easy-of-use and greater signal quality. You can find more detailed information in the following article:
In addition, the EMG sensor comes with standard stud connectors that are compatible with most of the electrodes available on the market, which makes it possible to experiment with other options including textile electrodes.
We also provide hardware customizations, such as electrode adapters for this sensor, should the electrodes of your choice be not compatible with our standard electrode interface.
My signal appears to be noise. What can I do?
There are a variety of factors that can impact your signal quality, ranging from issues with your electrode placement up to technical issues with your setup.
Find out more about the possible impact factors in the following article:
My signal acquired is not in millivolt (mV). What should I do?
OpenSignals uses both the sensor’s raw digital output as also converted into the correct sensor units.
To record, visualize, and export sensor data in the correct sensor units, make sure that you have setup your device correctly before the acquisition and find out more about the different formats in our output file specifications article.
If you use our developer tools, the acquired data is provided in the raw digital output only and needs to be converted into the sensor units by applying the transfer function available in the sensor documentation. You can find an example of how to do this in this transfer function article.
What signal processing software do you provide for the EMG sensor?
We offer two signal processing add-ons for our OpenSignals software.
The EMG Analysis add-on is suitable for detecting individual muscle onsets (=activations) and extracting statistical parameters (both temporal and amplitude parameters) from the individual onsets.
The Muscle Load add-on provides muscle load-related information over the accumulated EMG signal, i.e., the resulting information is extracted from longer signal acquisitions and over multiple muscle onsets, which is a good tool for fatigue evaluation:
Both add-ons are included in the biosignalsplux Professional & biosignalsplux Hybrid-8 kits but can be purchased additionally for other kits.
Is this sensor suitable for use in physiotherapy or other clinical applications?
All our products, including this sensor, are designed for use in life science education and research and not certified for medical use.
You can find more information about this topic in our regulatory article.
If you’d like to develop your own solution using this sensor, we recommend starting of with this article on this topic.