A 3.4µW CMOS image sensor with embedded feature-extraction algorithm for motion-triggered object-of-interest imaging

Distributed sensor nodes typically operate under the constraint of limited energy source, and power consumption is an important factor to extend the lifetime of sensor systems. Several low-power imagers have been reported for application to wireless sensor networks [1,2]. However, the biggest power consumption comes from wireless signal transmission due to the large bandwidth of image signals [3]. One way to reduce the bandwidth is to generate signals only when an event happens, by monitoring temporal changes [3-5]. However, this event-based imaging has extraneous redundancy because the sensor may also respond to environmental conditions, such as change of illumination or background movement in addition to actual target objects.