“…a team from Cornell University has created a water-sensing silicon chip that’s not only tiny, but is also reportedly ‘a hundred times more sensitive than current devices.’ What’s more, the chips might be possible to mass-produce for just $5 a pop. … the chip contains a tiny water-filled cavity. Once placed in soil, inserted in the stem of a plant, stuck in a cement matrix or put somewhere else, the chip exchanges moisture from that cavity with moisture in its environment via a nanoporous membrane. The chip measures any changes in the pressure within the cavity, that result from water either entering it or being drawn out.”
See on www.gizmag.com