We present waveSense, a low power hand gestures recognition system suitable for mobile and wearable devices. Anovel Selective Volumetric Illumination (SVI) approach using off-the-shelf infrared (IR) emitters and non-focused IR sensors were introduced to achieve the power efficiency. Our current implementation consumes 8.65mW while sensing hand gestures within 60cm radius from the sensors. We introduced the concept and the theoretical background of waveSense, details of the prototype implementation, and application possibilities.