FAQs

ExG is a term used to summarize all electrograms: EEG, ECG, EMG, EOG, and EGG. Whatever ExG you are using, Mentalab has the appropriate caps, electrodes, and cables. In fact, depending on your set-up, a single Mentalab Explore system can handle different electrograms simultaneously, as long as they use a shared reference.

Mentalab Explore devices support three recording modes:
1. Offline recording to internal memory
2. Wireless Streaming via Bluetooth
3. High-bandwidth streaming via USB

The internal storage has 8 GB. An 8-channel sleep recording of 8 hours will at 250 Hz result in a ~275 MB file in internal memory.

Battery live depends on recording mode and sampling rate. For our latest Explore Pro devices, battery life at 250 Hz is up to ten hours.

ExG data is recorded at up to 8000 Hz (users' choice; maximum sampling rate dependend on recording mode and channel count). Explore Desktop visualizes ExG data at 125 Hz. Orientation data is both recorded and visualized at 20 Hz.

Our hardware applies a first order differential low-pass filter as an anti-aliasing filter with a cut-off frequency of 3.6kHz. The noise-shaping converter includes a digital third-order, low-pass, sinc filter with variable-decimation rate depending on the data rate. Its -3dB-Bandwidth is roughly a quarter of the output data rate. ExG data are always recorded as raw data, giving you full flexibility for applying further filters in post- or real-time processing.

Mentalab Explore devices have a built in IMU (inertial measurement unit) containing an accelerometer, a gyroscope, and a magentometer with three axes each.

1. The accelerometer measures acceleration of the device in three directions (front to back, side to side, up and down).
2. The gyroscope measures angular velocity, i.e., the speed at which the device is moving along three axes (pitch, yaw, and roll).
3. The magnetometer measures the earth's magentic field along three axes. This can be used to determine the absolute orientation of the device within the magnetic field.

Try moving and turning the device while visualizing the orientation data in Explore Desktop to get a feel for the three sensors. The orientation data are useful for determining the head position of the participant or for actigraphy measurements of physical activity.

The accelerometer measures gravitational acceleration (G: ~9.8 m/s/s) and the amplifier's relative acceleration. Most of the time, the acceleration of the amplifier relative to G is tiny, which means one accelerometer line will be offset by G. Which of the three lines is offset depends on the orientation of the amplifier.

Yes, the Mentalab Explore amplifier is DC-coupled. However, do note that its working range is ±400mV.

The Mentalab Explore system combines REF and GND electrodes into a single channel. This is possible because the amplifier is so mobile, which means it is battery powered and small. In addition, the electrode cables are very short which allow us to use a single reference electrode.

Mentalab Explore Pro uses Bluetooth Low Energy (BLE), allowing for long battery life.

The LED color and blinking pattern convey relevant information about your amplifier's status. A complete list can be found in our LED Light Guide.

The single button can be used to send a number of commands to the amplifier. A complete list of button commands can be found in our Button Command Guide.

A full charge takes about 2 hours depending on the charger and environmental conditions.

If you leave your Explore amplifier plugged in when it is fully charged, there will be some decline in its battery capacity. We recommend unplugging your amplifier after each full charge, which normally takes 2 hours. If your battery has declined so much that it is unusable, please contact us at support@mentalab.com and we can repair or replace your amplifier's battery.

Impedance measurement is supported through our graphical user software Explore Desktop, Explore Mobile, as well as through our open-source Python API explorepy.

The internal memory of your Explore amplifier is full. The Explore amplifier will refuse to record any more data while its memory is full. To solve this, either transfer the data from your Explore amplifier to a computer using a USB-C cable, or, if you no longer need the data stored on the amplifier, double click your Explore amplifier while it is flashing the pink LED. Double-clicking the button will delete the internal memory of your Explore amplifier and allow you to start recording. See our Light Guide and Button Guide for more.

If you want synchronize data streams from different hardware components, we recommend using software platforms specifically designed for this. explorepy can push data to lab streaming layer.

We generally reccomend using separate receiver devices (computer or mobile) for each amplifier. Also see our integrations section for various software solutions.

Our dry electrodes are made of a conductive carbon-filled polymer with AgCl-coating. This material feels similar to soft rubber. The combination provides high comfort with great conductivity.

The life expectancy of your equipment depends on how you care for it. Under optimal conditions, you can use your materials for 10 years or longer. We provide a 2 year warranty on both cables and electrodes, and have tested these components for 200 sessions without degradation.

Yes, our alligator and button connector cables can connect to standard stick and peel electrodes as long as they have a conductive knob on the back. We can provide compatible, adhesive stick and peel electrode.

Choose an appropriate XS, XS/S, or S cap, as there is a lot of variability in head size between babies, toddlers, and infants. Experiment with removing the chin strap for added comfort. For more on infant EEG research, check out our blog post on the subject.

This cannot be done in explorepy and Explore Desktop directly, but it can be achieved with basic post-processing. Simply subtract the signal of the second reference channel from the subset of other channels. As a result, the values for these other channels will look as if they were recorded against the second reference. A real-time visualization can be achieved using LabChart Lightning.

With ease! Simply subtract your second reference channel from the other channels. This can be done in OpenViBE or a Python script. For more, please reach out to us at support@mentalab.com

Combining ECG and EEG recording is possible. However, both electrograms must share the same reference electrode, which may affect EEG signal quality. To minimize this effect, put the ground electrode on the scalp (not chest) and measure ECG with respect to that. The remaining cross talk will be:
10Hz input : -64dB
25Hz input : -75dB

Please see the Integrations section for a complete list of analysis software that works with Mentalab Explore. As a general guideline, our open source Python API explorepy can push data directly to lab streaming layer and we are also integrating with [Brainflow](https://brainflow.org/). Please feel free to reach out if you would like to discuss your integration needs. If you would like to build your own integration, we provide an open source SDK and our technical team is always happy to help.

Transmission to cloud storage has been tested successfully. For more details, please contact our support.

The time stamps generated by the Mentalab Explore Pro amplifier are very precise. You should expect a slight yet consistent delay of ~50ms in data transmission via bluetooth. Syncing with other amplifiers can be done using third-party software, like lab streaming layer. Please contact support for more detailed information on the topic.

All data is stored in CSV or BDF format. Filters that are applied in our software (explorepy, Explore Desktop, Explore Mobile) only affect visualization. The recorded data files will always contain raw data. You can record data in other formats using and other third-party software solutions that supports lab streaming layer (e.g. LabRecorder, OpenVibe etc.). We are happy to support you in converting your files to the format you need.

You can find an overview as well as a detailed list of available command line inputs in our explorepy command guide. Check out our full explorepy documentation as well.

You can use explorepy from most Python command terminals. However, we do recommend using Anaconda to manage your virtual environment dependencies, and Anaconda prompt to run custom Python scripts. If you use the executable installer, you can also operate explorepy from a Windows command prompt.

We have heard reports that some terminals do not run explorepy smoothly. These terminals include:

• Spyder Shell
• Jupyter Notebook Shell