True, for now, but there’s this:
[url]http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2018&mcparam=en550540
And perhaps, one day, it could be batteryless, maybe with a special paint that acts as the collector array:
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2018&mcparam=en551435
Might be a while, of course. And certainly a while to be economical, but the technology is being developed.
[raises thumbs, points to self]–I’m just a grunt, but I make this stuff. 😀