The ECG has progressed a long way. Shown on this slide is Willem Einthoven’s first practical electrocardiogram, which was developed in 1903. As can be seen, the subject is sitting in a chair with both hands submerged in the first electrodes; these are buckets with a fluid, connected for the right arm, left arm, and left leg. The point of this illustration is that the same function can now be implemented in a much smaller form factor, on a PCB.