Sony has had a US patent application published on the 21 November for its Wearable computing device, which is for a wig containing sensors. The idea is that the wig hides the sensors, and gives plenty of scope for placing the sensors. One of the drawing pages is shown below.
article on "SmartWig". As it points out, the idea of wearable sensors is likely to become a big growth area in technology. Rather than having a device in your hand or in your pocket, it's easier to simply wear it.
Time will show which technology wins out -- maybe several will survive as competitors. The obvious one is Google's glasses, published as Wearable device with input and output structures. Watches are the other main area so far. Until the technology settles down, perhaps, it will be hard for anyone trying to identify relevant patents to find them -- not every relevant patent document will have the word "wearable" teamed with words like "sensor" or "device" or "computing".
This is a list of (mostly relevant) World patent applications whose titles combine wearable with sensor or computing etc. That is a very crude search, and no doubt many more are out there.
I did not trace a European patent application for the same invention, which apparently has not yet been published. I expect this to be published soon. The advantage of seeing it is the ability to review the search report which is usually available with it, listing prior art.