E4 wristband data

Data export and formatting from E4 connect

Accessing E4 data: The only way to access data from the E4 is via Empatica's Web Portal, E4 connect. The interface allows researchers to visualize E4 session data, download sessions in CSV format, and flag them for permanent deletion.  Study manag...

Event Marking with the E4 wristband

Event Marking with the E4 allows real-time annotation of a session. Tapping the E4's button (<1 sec) during a session will illuminate the LED light (for 1 sec duration) and deposit a record in the session file of the button press time. Note the L...

E4 data - IBI expected signal

The inter-beat interval (abbreviated as IBI) is the time interval between individual beats of the heart. It's used to estimate the instantaneous heart rate. The IBI sequence provided by Empatica is obtained from the processing of the PPG/BVP signa...

E4 data - BVP expected signal

The BVP is the Blood Volume Pulse, and it's the primary output from the PPG sensor. The function it serves is explained here: Utilizing the PPG/BVP signal. The BVP signal is provided as a .csv file that can be downloaded from our E4 Connect portal...

E4 data - EDA Expected signal

There are two main components to the overall complex referred to as EDA. One component is the general tonic-level EDA, which relates to the slower acting components and background characteristics of the signal (the overall level, slow climbing, sl...

E4 data - HR.csv explanation

In the session zip archive, together with the sensor readings csv files, there's also a file called HR.csv and it looks like the example below:   This file contains the average heart rate values computed in spans of 10 seconds. They're not derive...

Publications citing the E3 wristband:

Okruszek, Ł., Dolan, K., Lawrence, M., & Cella, M. (2016). The beat of social cognition: Exploring the role of heart rate variability as marker of mentalizing abilities. Social Neuroscience, 1-5. http://www.tandfonline.com/doi/abs/10.1080/17470919...

Recent Publications citing the E4 wristband:

Onton, J. A., Kang, D. Y., & Coleman, T. P. (2016). Visualization of Whole-Night Sleep EEG From 2-Channel Mobile Recording Device Reveals Distinct Deep Sleep Stages with Differential Electrodermal Activity. Frontiers in Human Neuroscience, 10. htt...

Session start-time format and synchronization

How the time is set The time-stamping of data depends on the method of recording. In streaming mode (when you're connected to another device over bluetooth) the time-stamp is derived from the connected device, i.e. and iPhone running the E4 realti...

How is IBI.csv obtained?

The IBI sequence provided by Empatica is obtained from an algorithm that already removes wrong peaks. The picture below depicts a typical situation where the PPG data is corrupted by motion artefacts (graph a). The green points are the good heart ...

Utilizing the PPG/BVP signal

The PPG (Photoplethysmography) data is provided by the E4 device. This is also known in the scientific literature as BVP (Blood Volume Pulse).  We suggest you to read the following articles before starting to analyze the BVP data: Pulse oximetry ...

Have you done comparative studies or validation of the heart rate obtained from the E3/E4?

On E3 continuous heart rate data: The E3 performs admirably when compared to consumer health and fitness devices. It has the advantage of providing continuous heart rate with precise inter beat interval (IBI) information that is not interpolated....

Have you done comparative studies or validation on Electrodermal activity sensor?

On Electrodermal Activity: The E3 samples EDA at 4 Hz in order to support analysis and summarization of phasic changes in the signal. Phasic skin conductance measurements are peaks in the signal that are typically associated with short-term events...

Recommended tools for signal processing and data analysis

E4 connect currently offers data visualization but the most powerful insights will come from objective quantification of Empatica data. If you're looking for some tools for signal processing and analysis we can help!For systematic Skin Conductance...

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