Technical Specifications; Ppg Sensor; Eda Sensor; Infrared Thermopile - Empatica E4 User Manual

2.1 TECHNICAL SPECIFICATIONS

The user should refer to the Technical Specification document to have a better overview.
Below we will review only the main technical specifications.
The expected life of the device depends mainly on the battery life which is 2 years.

PPG sensor

•
Sampling frequency 64 Hz (Non customizable).
•
LEDs: Green (2 LEDs), Red (2 LEDs) Photodiodes: 2
units, total 15.5 mm
•
Sensor output: Blood Volume Pulse (BVP) (variation
of volume of arterial blood under the skin resulting
from the heart cycle).
•
Sensor output resolution 0.9 nW / Digit.
•
Motion artifact removal algorithm:
•
Combines different light wavelengths.
•
Tolerates external lighting conditions.

Infrared thermopile

•
Sampling frequency: 4 Hz (Non customizable).
•
Range:
•
-40...85°C for ambient temperature
(if available)*.
•
-40...115°C for skin temperature.
•
Resolution: 0.02°C.
•
Accuracy ±0.2°C within 36-39°C.
Water resistance:
•
IP 22 - E4 is protected against insertion of fingers
and will not be damaged or become unsafe if
exposed to vertically or nearly vertically dripping
water.
* This is not generally available but can be turned on with custom engineering work.
sensitive area.
2

EDA sensor

•
Sampling frequency: 4 Hz (Non customizable).
•
Resolution: 1 digit ~900 pSiemens.
•
Range: 0.01 µSiemens – 100 µSiemens.
•
Alternating current (8Hz frequency) with a
max peak to peak value of 100 µAmps (at 100
µSiemens).
•
Electrodes:
•
Placement on the ventral (inner) wrist.
•
Semi-permanent (screw in design).
•
SUS03 stainless steel (standard) or Silver (Ag)
plated with metallic core.
•
Electrode longevity:
•
Lifetime (SUS03)
•
4–6 months (Ag)
E4 operating range:
•
Relative Humidity 60 ±25% H.R.
3-Axis accelerometer
•
Sampling frequency: 32 Hz (Non customizable).
•
High sensitivity motion detection across 3 axes:
X,Y, and Z.
•
Default range ±2g.
•
Ranges of ±4g or ±8g are selectable with custom
firmware.
•
Resolution: 8 bits of the selected range.
empatica 2015
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