What is an ECG sensor?
Electrocardiogram (ECG / EKG) sensors are one of the latest technological additions to smartwatches to improve their tracking capabilities. The technology is designed to help people keep closer tabs on their heart health and can also be used to help identify atrial fibrillation (Afib), a serious medical condition that is a leading cause of stroke.
Most wearables today have optical heart rate monitors inside them which flashes LEDs to penetrate the skin and detect blood flow. However, the accuracy of this method is limited. On the other hand, a the technology of ECG, that is available for a lot of years, has a much higher accuracy
How does an ECG sensor work in a smartwatch?
Smartwatches carry out an ECG measurement by completing an electrical circuit across the wearer's body. The watch has two contact points to do it - the heart rate monitor of the back of the case pressed against the wrist, and when the wearer touches the front or side of the case with a finger from the opposite hand.
In the Apple Watch we see a single-lead ECG with a titanium electrode in the watch's digital crown and a layer of chromium silicon carbon nitride on the back of the watch. As mentioned above, putting a finger on the device closes the circuit between the finger, heart, and wrist which enables the watch to record the electrical impulses that make your heart beat.
Why is it important?
The purpose of the ECG functionality is to check for heart problems like Afib, a condition that can cause an irregular or abnormally fast heartbeat. The ECG sensor records the time and strength of the electrical signal that makes the heartbeat, the ECG app then monitors these signals to receive your heart rate and check whether upper and lower heart chambers are in rhythm or not. If they're not in rhythm, it could be a sign of arrhythmias (irregular heart rhythm). Complications of heart arrhythmias may include stroke, sudden death and heart failure and are associated with an increased risk of blood clots.
Through the Terra API, we provide connections to a range of different devices that contain ECG sensors so that users can stay on top of their heartbeats.
Below is a list of the wearables that contain ECG sensors today:
- Apple Watch series 4–7
- Samsung Galaxy Watch 4, 3, 2, Active 2
- Fitbit Sense, Charge 5
- Withings ScanWatch, Move ECG
- Coros Vertix 2
