A hybrid CMOS imager with sensing and energy harvesting capabilities

The design and test of an imager that can perform the tasks of sensing and energy harvesting is presented. The imager is based on hybrid pixels whose photodiodes that can be configured to work as photosensors or tiny solar cells. The hybrid pixels allow the imager to harvest energy in between frames or while it is in sleep mode. As a proof of concept a 32 × 16 array of hybrid pixels has been designed and fabricated in a standard 0.5 μm CMOS process. A charge pump to boost the inherently low voltage of the photodiodes when they work as solar cells was also designed. The charge pump employs flying capacitors to maximize the amount of energy that can be harvested. Measurement results show that up to 3 μW of power can be harvested from the array under indoor illumination conditions. Images acquired with the imager are presented.