Signal noise can be caused by many different factors, but there are certain recognizable conditions which are most likely due to a loose electrode or a possible issue with the sensor or wiring.
Now we’ll look at some common issues that result in poor quality EDA. They will help you identify sessions where they may be an issue with the sensor or how the device is worn.
a) Examples of EDA recorded with possible faulty wiring.
- Values suddenly drop to 0:
Zoom In (3 minutes):
- Values remain steady at 0: if you're recording in Streaming mode, you'll see the error message: "Not on wrist".
or a longer session
b) loose device: if the E4 is not worn snugly, the movement between the band and the wrist could cause artefacts with the accelerometer and the BVP signals as well. The EDA could assume 0 values because the electrodes have not established good contact with the skin, and the signal may never reach the physiological baseline that indicates strong electrode-skin contact.
If you're experiencing the issues presented above, inspect the electrodes for oxidation: for further instructions please check this link: electrode materials and replacement.
Afterwards, please try removing the E4 electrodes by hand. Replace the electrodes (or tighten them as much as possible by rotating them clockwise by hand if you have an older E4 version). Try generating a new recording and see if the situation has been resolved.
If the issue is not resolved, report the issue to firstname.lastname@example.org, making sure to provide at least one example session ID in the report for efficient service. The support team may suggest performing some experiments, following the instructions in this article: E4 data - EDA electrodes test