At first glance, I was expecting the brush itself to be powered by a motor, which would have provided lots of scope for reusing the device. Disappointingly, this doesn't seem to be the case - the hairbrush still requires you to manually brush your hair, but it does have an awful lot of sensors to take advantage of:
The Kérastase Hair Coach Powered by Withings minimizes these risks, taking advantage of multiple sensors that provide information on the quality of hair and brushing patterns. These include:
- A microphone that listens to the sound of hair brushing to identify patterns, providing insights into manageability, frizziness, dryness, split ends and breakage.
- 3-axis load cells that measure the force applied to the hair and the scalp when brushing.
- An accelerometer and a gyroscope which help further analyze brushing patterns and count brush strokes, with haptic feedback signaling if brushing is too vigorous.
- Conductivity sensors to determine if the brush is being used on dry or wet hair in order to provide an accurate hair measurement. The brush itself is splash proof.
(from the Press Release you linked)
With this information, I think there's a lot of choice for what to use the brush for. New Statesman has a rather nefarious idea for what could be done:
Munro hasn’t yet looked at the Hair Coach, but he speculates about the security of any IoT device with a microphone and internet connection. “Listening to hair breakage requires a microphone, so can it hear more than just breaks? It’s clearly very sensitive, so could it detect human voice and potentially become a spy bug?”
You could, in theory, take advantage of the hair brush's microphone to act as a sound detector (perhaps for security?), although I doubt the microphone is particularly sensitive - its original purpose only requires it to pick up sounds within a 10 or 20 centimetre radius.
Even so, if you put the brush in a key location, the microphone could perhaps detect someone walking past, and you could write some software to push a notification to your phone and inform you.
It's hard to know exactly how (or if) this could be done without more information on the product, which we can't know until it's released, but I'm sure if you were inventive enough, you could overwrite whatever code they have installed (unless the device only contains read-only memory, which is a strong possibility).