Developed by Oklahoma physician and entrepreneur Dr. David Albert, a true single-lead ECG for the iPhone 4 has been created using a unique skin for the device (shown). The iPhone can store a pdf of the signal and also transmit a realtime wireless signal about a foot using the iPhone’s battery.
Until now, most other free applications have used the camera feature of the device to display a person’s heart rate, rather than their actual electrocardiogram. Here’s Dr. Albert’s demo video: