| A novel distributed sensing platform is proposed that integrates image sensing, power generation, computation, and communication on to a monolithic device on the order of 100 microns in size. As a proof of concept, several subsystems of this proposed device are prototyped (in hardware or software) and characterized. A fully-integrated image sensor composed of metal diffractive optics over a CMOS active pixel sensor is implemented, demonstrating angular resolution of 0.2 radian with 450 nm blue light. Software models indicate that variants of this sensor are predicted to achieve resolution of 0.1 radian or better, and that deconvolution and noise-suppression techniques can be used to separate colour channels and to improve image resolution. An extremely low power analog to digital converter is implemented, performing log-scale digitization with 3 bits of precision in the log domain (5-10 codes) at a sampling rate of 18-36 kHz with a supply voltage of 0.8-1.2 V and a current draw of 6 muA. Simulations indicate that variants of this architecture can perform digitization using 1.7-4.7 pC of charge per conversion with a supply voltage of 0.8 V and a sampling rate of up to 2-4 MHz. Lastly, photovoltaic arrays composed of Darlington-connected stacks of cells are implemented on bulk CMOS and characterized, in order to assess the feasibility of monolithically integrated photovoltaic power generation in situations where silicon-on-insulator processes are not available. The conclusion from this investigation is that parasitic effects prevent this and similar architectures from producing useful power. The performance, area, and energy consumption of the prototype image sensor and analog to digital converter are consistent with the goal of future integration into a self-contained 100-micron sensor package. |
