Image sensor/energy harvesting IC

An image sensor which is also an energy harvester has been developed by University of Michigan researchers.

A paper on the chip entitled  ‘Simultaneous Imaging and Energy Harvesting in CMOS Image Sensor Pixels,’ has ben published by the four researchers: Sung-Yun Park, Kyuseok Lee, Hyunsoo Song and Euisik Yoon.

In effect the chip has a solar cell for each pixel, raising the possibility of a self-powered camera which works forever.

The authors  write: “We present a prototype CMOS active pixel that is capable of simultaneous imaging and energy harvesting without introducing additional in-plane p-n junctions. The prototype pixel uses a vertical p+/nwell/psub junction that is available in standard CMOS processes. Unlike the conventional CMOS electron-based imaging pixels, where the nwell region is used as a sensing node for image capture, we adopted a hole-based imaging technique, while exploiting the nwell region for energy harvesting at a high fill-factor of >94%.”

“To verify the feasibility, CMOS image sensors are fabricated and characterized,” add the researchers, “we successfully demonstrated that the energy harvesting can be achieved with a power density of 998 pW/klux/mm2, while capturing images at 74.67 pJ/pixel. The fabricated prototype device has achieved the highest power density among the recent state-of-the-art works and can self-sustain its image capturing operation at 15 fps without external power sources above ~60 klux of illumination.”

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