According to IEEE Spectrum, University of Michigan (UM) researchers have built a simultaneous imaging and energy-harvesting sensor.
The team of four built a prototype sensor that can capture 15 images per second powered by the sun. Both solar cells and image sensor convert light into electricity. Combining the two methods paves the way toward self-powered cameras.
Integrating a processor, wireless transceiver, and energy-harvesting imager, you could “put a small camera, almost invisible, anywhere,” says Euisik Yoon, UM professor of electrical engineering and computer science, and leader of the research, according to IEEE Spectrum. The device has the potential to operate indefinitely.
The prototype, which has five micrometer-wide pixels, has a second diode beneath the photodetector that acts as a photovoltaic. This design choice picks up stray photons missed by the sensor, which is then converted into electricity. In addition, the region of pixels can devote its time to sensing the image.
According to Samuel K. Moore of IEEE Spectrum, the chip “was capable of the highest power harvesting density (998 picowatts per lux per square millimeter) of any energy-harvesting image sensor yet. On a sunny, 60,000-lux day that’s enough power for 15 frames per second. Normal daylight conditions (20,000-30,000 lux) reduce that to 7.5 frames per second.”
Next, the team will optimize the sensor’s power consumption, frame rate, and required lighting conditions.
The article, “Simultaneous Imaging and Energy Harvesting in CMOS Image Sensor Pixels,” is published in the journal, IEEE Electron Device Letters.
