Glasgow Neuro Ltd, a young Scottish firm, has released an open-source data acquisition device for wearable health monitoring applications. The new device is called Attys, it is a wearable high precision bluetooth data acquisition device with a special focus on bio-signals such as ECG, EMG, EEG & EOG.
Record heart activity (ECG), muscle activity (EMG), brain activity, eye movements (EOG), temperature, pressure and any other sensor signal at 24 bits resolution and transmit it uncompressed to your smartphone, tablet or PC.
Develop rapidly your own health apps with the Attys by using our open source software as a starting point.
The Attys is a general purpose data acquisition device and is perfect for teaching where students can write apps for their own mobile phones, tablets or PC.
STEPS on how to record ECG, EMG
One ECG lead: Einthoven II
- right shoulder/arm: “-“
- left hip/leg: “+”
- right hip/leg: “GND”
This is the most popular configuration which usually has the strongest signal.
Two Einthoven channels with shared electrode
The Attys can also be configured to record in the classical Einthoven fashion where one of the electrodes is shared between two channels. Select the special Einthoven/ECG mode in AttysScope (Android) or in the JAVA/C++ API for both channels. In this configuration the two “+” inputs of the Attys are internally connected so that we need to connect only one electrode to “+”. The 2nd Channel measures then between the “+” electrode and “GND” so that the GND electrode has two roles: it provides the “-” electrode of channel two and acts as the overall reference.
Channel 1 records Einthoven II and Channel 2 of the Attys Einthoven III:
- right shoulder: “-” connected to Channel 1
- left shoulder: “GND”
- left leg: “+” connected to Channel 1.
Channel 1 records (the inverted) Einthoven II and Channel 2 of the Attys (the inverted) Einthoven I:
- connect the right shoulder to “+” of Channel 1
- the left shoulder to “GND”
- and the left leg to “-” of Channel 1
Both channels need to be inverted to see the traces with the right polarity.
Wonder why not 3 Einthoven channels? Because you can just calculate the first Einthoven lead: I=II-III.
Two independent biosignal channels (ECG, EMG, EEG, EOG, …)
If you want to record two independent channels then use the differential inputs of channel 1 as before and in addition channel 2 is measured between the ch2 terminal and GND.
- Channel 1: “+” against “-“
- Channel 2: “+” against “GND”
For example for Holter style recordings one might want to place the channel 2 electrodes on the chest while channel 1 records Einthoven II.
Muscle activity can be measured by placing the +/- electrodes right over the muscles and the reference electrode (GND) close by.
This is a pretty complex topic — mainly because it’s hard to distinguish between brain activity and artefacts.
How to process your data
Here is a standard workflow:
- Record your ECG, EEG or EMG with AttysScope and then
- post-process the data with OCTAVE or MATLAB(tm).
This plot below was created with OCTAVE: