LiveAmp with Sensor & Trigger Extension for acceleration signal recording

LiveAmp is an ultra-lightweight, wearable amplifier that can record referential EEGClosedElectroencep- halography channels and bipolar channels.

A 3-dimensional acceleration sensor is integrated into the LiveAmp. Therefore, an additional sensor is not required to measure acceleration movements of the LiveAmp amplifier. For measuring acceleration of limbs or other objects, acceleration sensors can be used with the LiveAmp in combination with the Sensor & Trigger extension.

The signal recorded with the acceleration sensor is a low frequency signal, therefore it can be acquired with the lowest sampling rate. However, the sampling rate set in the workspace applies to all recorded signals. If the acceleration signal is recorded simultaneously with other signals, e.g. EEG, a higher sampling rate may be required depending on the specific application. If needed, downsampling can be easily applied to the acceleration signal offline.

The acceleration signal of the integrated accelerometer, as well as the external acceleration sensors, is not calibrated to the SI unit for acceleration (m/s2) but to g (~9.81 m/s2). This is the equivalent of acceleration acting on a mass when standing on the surface of the earth. To activate a degree of freedom, the corresponding box (“x”, “y”, or “z”) must be checked in the workspace ( Figure 27 and Figure 28 ). When using external acceleration sensors, gradient and offset must be set in the channel table ( Figure 27 (1D) and Figure 28 (3D)), check the box “Diff. Unit”, write “g” as “Unit”, 300 (1D sensor) or 1450 (3D sensor) as “Gradient” and 0 as “Offset”.

The other settings are dependent on your individual experimental requirements. For additional information about setting up a BrainVision Recorder workspace, please refer to the Recorder user manual.

Figure 27 BrainVision Recorder workspace settings for recording the acceleration signal (1D) with LiveAmp. Boxes "x", "y", and "z" must be checked to record acceleration with the internal sensor in three degrees of freedom. To use an additional 1D acceleration sensor, check the box "Diff. Unit", write "g" as "Unit", 300 as "Gradient" and 0 as "Offset" in the channel table. The other settings are dependent on individual experimental requirements.

Figure 28 BrainVision Recorder workspace settings for recording the acceleration signal with LiveAmp (3D). Boxes "x", "y", and "z" must be checked to record acceleration in three degrees of freedom. To use an additional 3D acceleration sensor, check the box "Diff. Unit", write "g" as "Unit", 1450 as "Gradient" and 0 as "Offset" in the channel table. The other settings are dependent on individual experimental requirements.