Last month Oppo teased its first smartwatch, but said nothing about specs. Now leakster Digital Chat Station posted that the watch will feature an ECG sensor. The ElectroCardioGram (ECG) sensor detects electrical signals from your heart. With this, it can read your heart rate (beats per minute) and rhythm (regularity), it can even spot signs of atrial fibrillation. Optical heart rate sensors that are prevalent on smart watches and bands only measure heart rate (and occasionally SpO2). Apple was the first to introduce ECG capability on a smartwatch (with the Apple Watch Series 4),...