Cheap Micro Water Sensors Help Engineers with Curing Concrete
Cornell researchers have developed a microfluidic water sensor within a fingertip-sized silicon chip that is a hundred times more sensitive than current devices. They hope to mass produce the sensors for as little as $5 each.
Civil engineers can embed these chips in concrete to determine optimal moisture levels as the concrete cures. The chip is fitted with wires that can be hooked up to a card for wireless data transmission or is compatible with existing data-loggers. Such inexpensive and accurate sensors can be strategically spaced in concrete for accurate measurements to monitor and improve the strength of curing concrete.
The sensors make use of microfluidic technology – developed by Abraham Stroock, associate professor of chemical and biomolecular engineering – that places a tiny cavity inside the chip. The cavity is filled with water, and then the chip may be inserted in a plant stem or in the soil where it, through a nanoporous membrane, exchanges moisture with its environment and maintains an equilibrium pressure that the chip measures.