Ring Sensors
| Sensors | Description | Metric | Max Sampling Rate¹ |
|---|---|---|---|
PPG | Heart Rate - optical | 400 Hz | |
EDA | skin conductance (µSiemens) | 400 Hz | |
ECG | Heart Rate - electrical | 800 Hz | |
Temp | Celsius or Fahrenheit | 20 Hz | |
Motion | G-forces (g) | 50 Hz |
Measurement Descriptions
Photoplethysmography
A photoplethysmogram (PPG) is a non-invasive method for measuring blood volume changes using light. It tracks the pulsatile waveform of blood perfusion in tissue, providing insights into heart rate, blood flow, and oxygen saturation. It's widely used in medical settings for pulse oximetry and in wearable devices for monitoring heart health.
Pulse Note: The photoplethysmogram output is not the raw photo diode signal—the waveform is pre-conditioned using proprietary algorithms.
Electrodermal Activity
Electrodermal activity (EDA) measures the electrical conductance of the skin, which changes in response to emotional arousal, stress, and other stimuli. It's commonly used in psychology and neuroscience research to assess sympathetic nervous system activation and deactivation. Two important metrics are derived from EDA: the short term electrodermal response (EDR), and the longer term electrodermal level (EDL). EDA monitoring involves placing electrodes on the skin to measure changes in sweat gland activity, providing insights into autonomic nervous system function.
Electrocardiogram
An electrocardiogram (ECG or EKG) is a medical test that records the electrical activity of the heart. It involves placing electrodes on the skin to measure the heart's rhythm, rate, and overall electrical function.
Body Temperature
Body temperature is the internal heat level of an organism, usually measured in degrees Celsius (°C) or Fahrenheit (°F). It's regulated by the body's thermoregulatory system and typically ranges between 36.5°C to 37.5°C (97.7°F to 99.5°F) in humans. Variations from this range can indicate health conditions like fever or hypothermia.
Please note, depending on the environment, the ring can take some time to reach thermal equilibrium as the thermocouple is bonded to one of the EDA electrodes. The absolute temperature is not calibrated to a reference source so the absolute measurement will vary from ring to ring. The temperature data stream is intended to provide accurate insight into the rate of change in temperature over time.
Accelerometry
An accelerometer measures changes in motion in three dimensional space, referred to as the X, Y, and Z axes. The data from each axis can be graphed separately or the 3 channels can be combined to show a resultant vector from 3 dimensional motion. The accelerometer is useful for indicating the time and intensity of a particular movement and can be used to indicate where motion disrupted the data from the other biometric sensors.
¹ Not all sampling rates may be run concurrently. Consult the Senstream App for defined sessions or contact Senstream for more info.
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