Researchers come up with a camera on light energy

Researchers at Columbia University have built a camera with a sensor that powers itself by placing the photodiodes in photovoltaic position, like a solar cell. This allows the device to continue shooting pictures without an external power source.

The research team built the internals of the test camera with commercially available components; the housing of the device came from a 3d printer. The sensor consists of a grid of 30×40 photodiodes. Unlike previous self-sufficient cameras, these are not only used for collecting image information, but also for generating power. As long as the light intensity is approximately 300 lux, the sensor can be read once per second. The rest of the time, the captured light energy is stored in a supercapacitor.

Photodiodes can be used in several ways. In a normal digital camera, the diodes are in a photoconductive position. A small amount of voltage is applied to the diode, causing it to respond more quickly to changes in light intensity. In the test camera, the photodiodes are in a photovoltaic position, like in a solar cell. As a result, the diodes do not use any current to measure the light intensity. According to the researchers, the response time of the diodes in good lighting conditions is still fast enough for a clear picture.

According to the research, a self-sufficient sensor of 200×200 pixels would theoretically be possible if it is read once per second at a light intensity of 300 lux. For situations in which the light intensity differs, the researchers came up with an algorithm that determines how often the sensor can be read. They see applications for their sensor design in wearables and internet-of-things devices.