Main > ELECTRONICS. > Humidity Bacteria Hybrid Sensor > Org.: USA. U. (Research) > Research Description

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Gilded bacteria sense moisture
Chemical engineers at the University of Nebraska, Lincoln, have designed and fabricated a humidity sensor made from living bacteria and gold nanoparticles (Angew. Chem. Int. Ed. 2005, 44, 6668). Vikas Berry and Ravi F. Saraf prepared the hybrid nanoelectronic device by depositing gram-positive bacteria on a silicon substrate with lines of gold electrodes. The bacteria form bridges spanning the electrodes. The two researchers coated the deposited bacteria with a monolayer of poly(L-lysine)-coated gold nanoparticles. They then applied a voltage across the electrode pairs and measured the current across the bacterial bridges. They showed that a humidity increase from 0% to 20% leads to a more than 40-fold decrease in the current. The decrease is induced by moisture, which causes the bacterial membrane to swell and increase the distance between the individual gold nanoparticles. “Our sensor is the first example of a nanodevice that integrates physical nanomaterials with a live microorganism,” Saraf says. “However, once made, the living part is not critical for the device to function.” He adds that the device is more sensitive than current humidity sensors for low-humidity environments.




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