A Highly Sensitive and High-Performing ‘Green’ Electronic Sensor

May 28, 2020 by Luke James

University of Massachusetts (UMass) Amherst researchers claim that they have developed bioelectronic ammonia gas sensor that uses electric-charge-conducting protein nanowires to create biomaterials for devices.

It is thought by some researchers that sensors based on biomaterials could lead to novel green technologies that tick all the right boxes: Low cost, renewable, and eco-friendly. Now, a team from UMass Amherst has reportedly developed a new bioelectronic sensor derived from the bacterium, Geobacter. 

In a paper published in Nano Research, the team claims that its new ammonia gas sensor is “among the most sensitive ever made,” because it facilitates “high-precision” sensing.


Electric-Charge-Conducting Protein Nanowires

According to the research paper, the sensor uses electric-charge-conducting protein nanowires derived from Geobacter sulfurreducens to provide biomaterials for electrical devices.  The nanowire sensor is able to respond to a broad range of ammonia concentrations up to 106 ppb, covering the range necessary for applications in biomedicine, industry, and the wider environment. 

“The sensor also demonstrates high selectivity to ammonia compared to moisture and other common gases found in human breath. These results provide a proof-of-concept demonstration for developing protein nanowire-based gas sensors for applications in industry, agriculture, environmental monitoring, and healthcare.”


Protein nanowires harvested from geobacter sulfurreducens and between electrodes.

An illustration depicting protein nanowires harvested from the Geobacter sulfurreducens and placed between electrodes (gold) to form the bioelectronic sensor to detect biomolecules (red). Image credited to University of Massachusetts - Amherst


High-Precision Sensing

The research team designed the sensor to measure ammonia because it is an important gas in these applications. In humans, for example, ammonia on the breath can signal disease, while in poultry farming, ammonia must be tightly controlled to promote good health and yield. 

“This sensor allows you to do high-precision sensing; it’s much better than previous electronic sensors,” according to Yao. “Every time I do a new experiment, I’m pleasantly surprised. We didn’t expect them to work as well as they have. I really think they could have a real positive impact on the world,” says first author and doctoral student Alexander Smith.


A Replacement for Electronic Sensors? 

Smith added that existing electronic sensors often exhibit limited or low sensitivity, and they can also be prone to suffering from interference from other gases. In contrast and in addition to “superior function and low cost”, the team’s bioelectronic sensor is produced sustainably by bacteria using renewable feedstocks and is also biodegradable, so it does not produce any electronic waste.

When Smith exposed the bioelectronic sensor to ammonia during experiments, the response was “noticeable and significant,” he said. “Early on, we found we could tune the sensors in a way that shows this significant response. They are really sensitive to ammonia and much less to other compounds, so the sensors can be very specific.” Other results from the team’s experiments reportedly demonstrate that the sensor’s nanowires are very stable and last a long time, enabling the sensor to function consistently and robustly in the long term. 

The ammonia-detecting bioelectronic nanowire sensor is the team’s first proof-of-concept. In the future, the team hopes to develop sensors for a range of other compounds.