E-field-based 3D gesture-recognition chip

Why has this not taken off? Off-the-surface gestures seem like they'd really enrich smartphone experience. I don't get why this low power proven tech has not been incorporated into phones. It's already 8 years old!

Hope to see an wristband which recognizes hand gestures soon. Together with smartphone head tracking it could open the window to useful everyday AR.

Article is from 2012.