A new Apple patent has been published online, which affects the company's future smart watches. According to the document,
The clock system will scan invisible to the eyeStrap ID. This will enable certain options on the device. For example, some users may want to check their blood pressure on an ongoing basis. The special Apple Watch band will be scanned by the watch sensor, and the system will have a special user interface to track the above indicator.
There may be several similar straps that activate different functions. Since this is a patent, it is not yet known when the Apple Watch with the new options will hit the market.