By tracking the levels of a plant growth hormone, the sensor improves the efficiency and effectiveness of fresh produce transport and storage
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Spotted: Semi-conducting carbon nanotubes detect the presence of ethylene, a plant growth hormone. Created by a team of Massachusetts Institute for Technology (MIT) researchers, the sensor reacts within seconds to the presence of the gas, even at very low levels. Most plants create progressively more ethylene throughout their life cycles, making the sensor particularly useful for growers who need to monitor the transport and storage of produce.
The nanotubes use palladium to create oxidation in the presence of ethylene, which makes the tubes conductive, and thus produces a current. The rise and fall of the current indicate levels of ethylene, providing a much more specific indication of the freshness of stored produce. The sensor is capable of detecting very low levels of ethylene, around 15 parts per billion, and when there is no gas present, the sensor remains in its resting, non-conductive state.
This new process of tracking freshness is an update on a previous MIT project. The earlier version of the carbon nanotubes used copper and was much less sensitive, incapable of detecting ethylene below 500 parts per billion. As useful for home growers and consumers as for commercial farmers and transport companies, the latest sensor is in development for widespread use, and the team have applied to patent it.