Self-Powered Image Sensor

EurekAlert: A research team led by Shree K. Nayar, Professor of Computer Science at Columbia University, has invented a prototype video camera, said to be the world's first fully self-powered - it can produce an image each second, indefinitely, of a well-lit indoor scene.

Self-Powered Pixel Design:
The photodiode PD is operated in photovoltaic mode with zero bias.
The voltage of the anode of PD increases to a level proportionate
to the incident lightenergy. In this case PD draws zero power to
produce a voltage proportionate to the incident light, and since it is
not biased it does not produce any dark current. An important feature
of the design is that emitter of transistor Q1 can be switched between
ground (for resetting) and a power supply (for harvesting).

Self-powered sensor assembly