Sensor Increases Detection Sensitivity of Ammonia Gas

Effectively Detects Ammonia Gas Concentration

This gas sensor detects ammonia gas by utilizing a highly electron mobility transistor (HEMT), a device used to amplify or switch electronic signals and electrical power. Ammonia gas is used to reduce nitrogen oxides (NOx) through selective catalytic reduction (SCR) to prevent acid rain and smog formation. Various industries currently use ammonia gas to reduce emissions from boiler flue gases, refinery off-gas combustion, gas and diesel engines, gas turbines in the power industry and chemical process gas streams and more. However, monitoring and detecting ammonia gas is a required step in the process because high concentrations of ammonia in the environment can cause pollution and be toxic to terrestrial and aquatic organisms. Additionally, ammonia is flammable and can cause respiratory issues. In 2013, an ammonia fertilizer company exploded in Texas, killing 15 people and injuring more than 260 people.

Researchers at the University of Florida have developed a gas sensor that contains a highly sensitive and thermally stable GaN based HEMT with ZnO nanorods on the gate region of the sensor. This invention detects ammonia gas and other nitrogen compounds at low concentrations, preventing uncontrolled levels from harming the environment. Detection of ammonia at low concentrations is necessary for the refrigeration, agricultural, automotive, and chemical industries.

Application

Gas sensor utilizes ZnO functionalized HEMT to increase detection sensitivity of ammonia gas

Advantages

• Detects ammonia concentrations at high temperatures up to 300°C, allowing operation in environments that typically destroy gas sensors
• Provides measurements without interference from other gases including oxygen, methane and carbon monoxide, increasing reliable results
• Provides quick response and recovery time, allowing user to address leaks in a timely manner
• Promotes chemical stability and corrosion resistance, increasing device longevity and efficiency

Technology

These gas sensors use GaN based HEMTs for low concentration ammonia detection. A layer of ZnO nanorods are used as functionalized gates to sense and measure ammonia concentrations. When exposed to ammonia, the conductivity of ZnO changes, causing the voltage readings from the sensor to change. The sensor works quickly and alerts its users when low levels of gas are present. The device can operate in harsh environments with high temperatures and receive no interference from other gases. This invention works both smoothly and efficiently, enabling its use in a variety of applications that require ammonia detection.