Some Apple patent applications have turned up that show what the folks in Cupertino are working that could be incorporated into future Apple Watch bands. One of the patents outlines a method that Apple is working on that would eliminate the need to enter a passcode on the Apple Watch or a paired iPhone to unlock the wearable.
The patent talks about skin texture cracks generally being warmer than surrounding skin and hair being cooler than the surrounding skin. The watchband could use an IR thermal image sensor as a wrist biometric sensor. Another patent sounds like something out of Back to the Future, and describes an Apple Watch band that can tighten itself.
A self-tightening band could be important if a user is exercising with the watch on and a tighter fit is needed to get a heart rate reading without interrupting the exercise regime. The band could also automatically loosen once the activity is over. The self-tightening band would also be location-aware and tighten itself at specific locations as needed.
Other cool potential uses the patent app outlines include tightening to signal of an upcoming turn when walking or driving. It could also grip harder to count off repetitions as the user exercises. The patent also talks about an odd method of using the watch band for 2-factor authentication by counting the number of squeezes it gives when logging into a bank website or other use.
The last of the patents talks about a watchband with an LED indicator on it that could visualize the progress of a task or activity the user is performing. This could be used to signify Activity, Stand, and Exercise rings or battery life. It's not clear if the patent apps surfacing now indicate the Apple Watch bands might be coming any time soon, but it's at least an interesting look at what's being thought up for a [potential] future release. Apple recently announced it would fix cracked screens on some Apple Watch models free of charge.