Faculty of Mathematics, Physics
and Informatics
Comenius University Bratislava

A unique hydrogen sensor from FMPI

The team of the Department of the Experimental Physics led by Prof. Plecenik designed a unique hydrogen sensor applicable not only in the automobile industry. The study was published in Sensors and Actuators B: Chemical.

21. 05. 2015 00.00 hod.
By: František Kundracík

In connection with expected boom of hydrogen as an environment-friendly fuel in car industry a need arises for simple and reliable system for detection of even small amounts of hydrogen, which is highly flammable and poses danger of explosion when discharged. The researchers of the Dpt. of Experimental Physics, led by Prof. Andrej Plecenik, developed such system. Compared to previous sensors working on the same principle, this novel device is highly sensitive at very low electric energy consumption and is thus suitable for portable appliances running on batteries. 

The heart of the sensor is a thin layer of titanium oxide (TiO2) whose electrical conductivity depends on the gas contents in the air. In the air of normal composition the substance is a good insulator. When, however, only a little amount of reduction gases (e.g. hydrogen or methane) is present, on the layer surface the gas reacts with the oxygen atoms, thus the electrical conductivity rapidly increases. The previous devices working on this principle had a drawback: they had to be heated up by hundreds of degrees Celsius for the abovementioned reaction to occur with sufficient effect. Such sensors had relatively high energy consumption and low endurance. In the novel sensor the sensitivity is raised by appropriate texture (graininess) of the layer, decrease of its size to nanoscale and non-conventional “sandwich” array. As has been found, proper adjustment of these parameters results in a sensor with high sensitivity at the room temperature without need for heating. If, for example, the amount of hydrogen in the surrounding atmosphere reaches 1%, the electrical resistance of the sensor drops up to million times. Such sensibility is sufficient for detection of very low hydrogen concentration which yet poses no threat of ignition and explosion.