Solar Cells Integrated In Microchips 38
cylonlover writes "In a new, more efficient approach to solar powered microelectronics, researchers have produced a microchip which directly integrates photovoltaic cells. While harnessing sunlight to power microelectronics isn't new, conventional set-ups use a separate solar cell and battery. What sets this device apart is that high-efficiency solar cells are placed straight onto the electronics, producing self-sufficient, low-power devices which are highly suitable for industrial serial production and can even operate indoors."
What economic use? (Score:4, Insightful)
what could such a chip be used for?
The important question to ask is, "what could such a chip be economically used for?"
Unless one is developing something for military or other national security-type purposes, where cost is typically significantly less important than attaining the ultimate in performance (however "performance" is defined in the application), the question typically is, "what's the cheapest way to do X?"
If, as is frequently the case, X is defined as "power the chip," one has an interesting economic quandary: In terms of money/area, conventional solar cells, especially amorphous solar cells, are about the cheapest form of silicon known to man. Using this new technology, though, these solar cells would be replaced by area on an integrated circuit, which is about the most expensive form of silicon known to man. Worse, the power consumed by the electronics must be minimized ("below 1 milliwatt"), so one is pressured into using very fine-lithography silicon, which is the most expensive form of silicon known to man.
The only way I can see that one wins on cost with this technology is if one has electronics that are so low-powered that they can be powered by an amorphous solar cell with an area equal to that of the circuitry itself. If you need a point of reference on the practicality of this requirement, I point you to your average solar-powered calculator, which has a solar cell area of several cm^2, and an active circuit area of probably less than 5 mm^2.
If, however, X is defined as "power the chip with a monolithic structure," perhaps for acceleration, board area, or other system-level requirements, then using external solar cells is prohibited (by the terms of the game), and then this technology begins to look more appealing. Even then, however, I would wonder if it wouldn't be easier to use chip stacking [siliconfareast.com] or similar technology to put a solar cell on a chip, since then each die could be processed in a manner optimum for its purpose (solar cell or integrated circuit). And, of course, you're still left with the problem of getting sufficient power from such a small area.