Smartwatches take an ECG by completing an electrical circuit across the wearer's body ... listed above perform the equivalent of a single-lead ECG, the KardiaMobile 6L, as its name suggests ...

[Dániel Buga], for instance, designed a compact ECG system the size of a credit card, cleverly dubbed Card/IO, that clearly demonstrates how to implement a single-lead ECG. Although obviously not ...

Figure 18B shows the 12-lead ECG of the entrainment tracing of Figure ... because we can record from "inside" the circuit and demonstrate the essence of entrainment. Thus, entrainment can occur ...