Today the U.S. Patent and Trademark Office officially granted Apple a patent that relates to future Apple Watch bands taking on sensors and circuitry so that the body of Apple Watch could be made much thinner over time. Today Apple's ECG is in the body of the watch. In the future, ECG sensors could be integrated into the band or "smart band." Apple also opens the door for a fitness band by describing "a wearable band without any wristwatch unit (e.g., a band of the type sometimes referred to as a health band, fitness band, or activity band.")

Apple's patent FIG. 2 below illustrates a possible future Apple Watch band that could support light-emitting diodes or tiny display; FIG. 15 is a diagram showing how a flexible printed circuit may be provided with connector contacts that allow the flexible printed circuit to couple to mating contacts in a connector on a watch unit or other electrical device structure.

Apple's patent FIG. 8 below is a cross-sectional side view of an illustrative band having an array of cavities with respective components such as light-emitting diode devices; FIG. 17 is a top view of an illustrative band and main unit in an electronic device showing how a buckle may be coupled to a band.

Apple's patent FIG. 19 above is a top view of a portion of a band with a display and an electrocardiogram electrode.

The types of sensors that could be used in future Apple Watch bands include those that gather environmental measurements and/or user input and may include ambient light sensors (visible light sensors, color sensitive light sensors, ultraviolet light sensors, etc.), optical proximity sensors, capacitive proximity sensors, temperature sensors, force sensors (e.g., for measuring biometric information), gas pressure sensors, heart rate sensors, blood oxygen level sensors (e.g., based on emitted and detected light), electrocardiogram sensors (e.g., sensors for measuring electrical signals on a user's body), particulate sensors (e.g., sensors that use light measurements and/or other measurements to measure particulate concentration in the air), image sensors (cameras), gas pressure sensors, carbon dioxide sensors and/or sensors measuring other gas concentrations, position and/or orientation sensors (e.g., inertial measurement units based on one or more sensors such as accelerometers, gyroscopes, and/or compasses), accelerometers for gathering user tap input, etc.

The bands could be made with materials ranging from elastomeric polymer to woven fabrics, metals, ceramic, wood, crystalline materials or natural materials.

This is a promising ongoing project at Apple and here are other patent-pending concepts on this theme of smart bands: 01, 02, 03 and 04.  

For more details, review Apple's granted patent 11,442,503.