Whether you’re growing wine grapes or mixing cement, there are some situations in which it’s vitally important to monitor moisture content. Normally water sensors are used, although these can be both large and expensive. Now, however, 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.
Known as a "lab on a chip" device, 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.