Writing in the journal NanoResearch, a team at the University of Massachusetts Amherst reports this week that they have developed bioelectronic ammonia gas sensors that are among the most sensitive ever made.

The sensor uses electric-charge-conducting protein nanowires derived from the bacterium Geobacter to provide biomaterials for electrical devices. More than 30 years ago, senior author and microbiologist Derek Lovley discovered Geobacter in river mud. The microbes grow hair-like protein filaments that work as nanoscale “wires” to transfer charges for their nourishment and to communicate with other bacteria.

First author and biomedical engineering doctoral student Alexander Smith, with his advisor Jun Yao and Lovley, say they designed this first sensor to measure ammonia because that gas is important to agriculture, the environment and biomedicine. For example, in humans, ammonia on the breath may signal disease, while in poultry farming, the gas must be closely monitored and controlled for bird health and comfort and to avoid feed imbalances and production losses.