New patent shows that Apple Watch ECG may require an additional armband

In a patent entitled Portable ECG Device granted to Apple by the U.S. Patent and Trademark Office on Tuesday, Apple explained how to create a heart monitoring device in some novel ways. One way is actually the way it is used in Apple Watch.

The way the ECG works is to have two contact points with the user at different locations on the body. These positions are usually chosen to keep the heart between two points. The patent mentions the existing digital crown electrocardiogram measurement method.

In the first version, Apple suggested using a wearable device whose shell is in contact with the skin, and an antenna is extended to capacitively couple with the body for the second potential point. As far as the existing Apple Watch is concerned, this takes the form of contact between the sensor and the wrist, and the user presses the digital crown with the fingers of the other hand.

The patent continues to describe the use of a so-called metal moat on the electrode surface, the outer and inner walls are grounded, an amplifier, and a parasitic capacitance reduction unit to correct the amplification result. The patent also includes two other implementations, but they are versions for performing the same task but in completely different ways.

An alternative involves a wearable device accompanied by another unit. Wearable devices will directly make capacitive contact with users, much like Apple Watch. The second device consists of an antenna and can be placed in the second position. In the picture, an armband is taken as an example.

The second unit communicates with the wearable device and provides additional ECG data from the second location. Although it can provide capacitive data, Apple suggests that it can provide readings by taking an electrocardiogram on the air gap. This can be interpreted as keeping the armband a few inches away from the user’s heart and being able to detect electrical signals from this distance.

Another option is a hybrid of the two technologies, which is mainly composed of the second technology, with a wirelessly connected antenna element connected to a device similar to an Apple Watch. However, instead of just relying on monitoring the heart through the air gap, the antenna is capacitively connected to the body. The armband can perform air-gap and capacitive measurements at the same time, and send the data back to the Apple Watch to collect as much data as possible for the user.

Apple submits a large number of patent applications every week, but although the existence of patents indicates areas of interest to the Apple R&D team, it does not guarantee that this idea will appear in future products or services.

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