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Unicorn Naked case and connectors for EEG, EMG and ECG

This page is part on a series on the Unicorn EEG system, see also the review of the Unicorn Hybrid Black, and the design and prototyping of alternative wet “sponge” electrodes.

The Unicorn Naked comes with the same dry electrodes and electrode leads (wires) as the Unicorn Hybrid Black. However, there is no real advantage of the Naked version over the Hybrid Black version if you want to use them with the same electrodes, unless you insist on a 3-D printed headset to hold the electrodes in place instead of a cap. We figured that the small size and weight, and it being wireless, made it an ideal candidate for developing a wearable system for EEG research on infants and children. At the same time, we sometimes have other applications where a small and wireless ExG system would be useful, for example to record EMG from the muscles or ECG from the heart.

This first image shows the result, further down on the page you can read more on the details and design considerations.

3d-printed unicorn naked case and connectors

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Calibrating the Sonoff ZNB02 zigbee temperature and humidity sensor

I recently installed a few Sonoff ZNB02 temperature and humidity sensors around the house. Monitoring them for some time, I noticed that the humidity level was higher that what is recommended for a comfortable and healthy indoor environment. Initially this got me worrying about the indoor climate, but as there are no other indications that it is so humid, it made me think that these sensors are perhaps not so accurate. Therefore I decided to calibrate them.

When you mix half a cup of normal kitchen salt with water into a sludge (i.e., a fully saturated solution) and put that in a closed container, that acts as a sort of constant humidity buffer for quite a wide range of temperatures. For a solution of NaCl at room temperature the relative humidity in the container will be 75%.

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