U.S. University of Michigan Engineers Successfully Develop Solar Imaging Sensors

China Instrument Network Instrument Development Recently, researchers at the University of Michigan developed a newly designed “self-powered” CMOS image sensor whose pixels can simultaneously perform imaging and energy harvesting. This design may open the way for future compact self-powered cameras. Devin Coldewey of TechCrunch, a technology media commented: “The newly designed sensor is essentially a camera that never needs a battery or wireless power supply.”

The research team has developed prototype CMOS active pixels that can simultaneously perform imaging and energy harvesting without the need to introduce additional planar PN junctions whose pixels use structures available in standard CMOS processes. The main author of the paper, Eusik Yoon, explained in the abstract of the paper: “Unlike conventional CMOS-based imaging pixels, the N-well region in the new sensor is used as a sensing node for image capture. We have adopted hole-based imaging technology. At the same time, the N-well region is used to collect energy with a high fill factor higher than 94%.

"Highest power density"

Euisik Yoon said: “We have successfully demonstrated that energy harvesting can achieve a power density of 998 pW/klux while capturing images at 74.67 pJ/pixel. Our current prototype device already achieves the highest power density and can achieve 15 The speed of the fps maintains its image capture without the need for an external power supply exceeding 60 klux of lighting."

According to the content of the paper, the new sensor will achieve a speed of 15 images per second under "clear weather of 60,000 lux" and 7.5 sheets per second under normal daylight conditions (usually 20,000 to 30,000 lux). The speed of image acquisition. According to reports, researchers are currently focusing on the development of proof-of-concept chips, and they pointed out in the paper that they have not optimized the power consumption of the sensors themselves.

The paper concludes: "We have proposed a prototype CMOS active pixel architecture that can simultaneously perform imaging and energy acquisition using a built-in embedded vertical PN junction in a standard CMOS process and use holes as imaging. The charge carriers achieve a high fill factor of 94%.To prove the feasibility of this design, we fabricated a CIS chip and conducted an energy harvesting test with a power density of 998 pW/klux, and at the same time generated a quality factor of 74.67 pJ/. The pixel image, which provides the highest power density.”

(Original Title: Engineers at the University of Michigan Develop Solar Imaging Sensors)