This article provides everything you need to know to start recording data with your BITalino Electromyography (EMG) sensor, sold in two different versions: UC-E6 and assembled (Fig.1).
Fig.1: BITalino EMG sensor, UC-E6 (left) and assembled (right) versions
You can learn more about the BITalino UC-E6 and assembled sensor in the EMG Sensor Datasheet and EMG Assembled Sensor Datasheet, respectively.
Connecting Your Sensor
If you are getting started with the BITalino EMG UC -E6 sensor version, you need to connect your sensor to one of the analog (An, where n ranges from 1 to 6) channels available in the BITalino Core (MCU+BLE/ BT +Power) unit as shown in Fig.2. You can connect either 2- or 3-lead electrode cables, depending on which arrangement you use. If you want to use multiple EMGs, you should connect a 2-lead electrode cable and then add a ground cable for reference. Otherwise, the 3-lead cable will also provide the reference for your signal.
Fig 2.: How EMG UC-E6 sensor must be connected to the BITalino Core Unit
Alternatively, you can connect your EMG UC -E6 sensor to an Arduino device. For this suggestion we advise you to read this support article.
When you start with the EMG assembled sensor version, your sensor is already connected to the electrode cable in a 3D printed housing. The EMG sensor is mounted in an electrode holder that takes into account the electrode spacing of 2 cm (see Fig. 3). This sensor version is usually combined with the Assembled BITalino Core BLE/BT.
If this is your use case, you can connect your sensor to one of the available analog (An, where n ranges from 1 to 6) channels highlighted in the back of the device (Fig. 3). The reference cable, i.e. the ground cable, can be connected to any of the BITalino ports. The system automatically subtracts the reference signal from the EMG signal.
Fig 3.: Representation of the BITalino assembled version of the EMG sensor and core unit.
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 (Fig. 4).
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 UC-E6 sensor’s electrode cables come with two colored sleeves to mark the positive (red sleeve) and the negative (black sleeve) (Fig. 2). The electrodes can be positioned in either way but along the muscle fiber and on the muscle belly.
To learn more about the EMG electrode positioning and signal acquisition you can consult the following documentation:
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).
To learn more visit our page “How to set up my BITalino in OpenSignals device manager?“
Frequently Asked Questions (FAQs)
What electrodes can I use the sensor with?
We offer pre-gelled, adhesive, and disposable electrodes and dry and reusable electrodes.
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:
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:
What signal processing software do you provide for the EMG sensor?
We have in our product 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:
