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Tiny, cheap water-sensing chip outperforms larger, pricier sensors


October 18, 2013

Doctoral student Vinay Pagay holds one of the chips

Doctoral student Vinay Pagay holds one of the chips

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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.

In order to relay the data it gathers, the chip must be connected to a Wi-Fi card, a data logger, or some other device that can either transmit or record information. One chip can reportedly last outdoors for at least a few years, although freezing temperatures may cause it break.

The Cornell researchers are now establishing how moisture readings made by the chips translate to plant growth, so that users can make sense of their data.

Already, Welch's juice company and the Ernest and Julio Gallo winery have expressed interest in the technology.

Source: Cornell University

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

Quality hygrometers are notoriously expensive, I'd love to buy one cheap so I can monitor the basement.


So you say they are expensive now but will become cheap, I don't suppose these will be available within the next 150 days?


I wonder if this is really all that great a story ! In most cases like what Grunchy refers to it is relative humidity that one would be interested in monitoring. I bought a monitor that tracks the temperature and humidity for under $ 10/=. I find the temperature to be accurate to within 1/2 a degree Celsius and RH to within 2 - 3 %. This should serve for most of the Household situations.


I think some existing ones are dangerous as well, using radioactive decay to determine moisture content. (My Geiger counter went off one day when a farmer parked near me, and some sleuthing later revealed his explanation: he'd "been meaning to fix the case on the moisture tester for some time"...)


I'm thinking that this device could be used in electronic devices that are used in harsh enviroments where water ingress will potentialy cause failure.

John Findlay

It's a good thing these are planned to be used where there aren't any chemicals (like ammonia fertilizers, herbicides, etc), there isn't any dirt, or presence of other materials, that can block the membrane or contaminate the reference well...oh, wait a minute...


Is this chip a demonstration of a chemical sensor based on zeolite membrane technology? I don't know any specifics about the nanoporous membrane, but if it has hydrophilic groups on its surface and narrow pore size distribution I think it will work very well.

In that case, likely the sensor is designed to have very high selectivity through molecular sieving and so diffusion of water through its pores over less polar contaminants will be dominant. How curious.

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