Real-time detection by properties of tin dioxide for formaldehyde gas sensor

This paper presents real time detection of formaldehyde gas by using the properties of tin dioxide (SnO
₂
) thin film on a formaldehyde gas sensor. SnO
₂
thin film is coated on aluminum IDE electrodes which is fabricated on a glass substrate by using sol-gel technique and annealed to get the crystallization of SnO
₂
. The surface morphologies of the SnO
₂
thin film is examined and studied through atomic force microscopy (AFM). For the real-time detection, formaldehyde gas was inject inside the gas chamber. The hot plate with the temperature of 200°C inside the gas chamber is used to evaporate the formaldehyde gas, subsequently exposing it to the surface of SnO
₂
thin film. Electrical conductivity of the SnO
₂
thin film is increased and allowed current to flow through it. The potential difference at the gas sensor is measured using voltmeter. During real time detection, various amount of formaldehyde liquid which are 0.1 μl, 0.3 μl, and 0.5 μl are injected into the gas chamber, thus produced potential differences of 0.8 V, 2.2 V and 3.5 V, respectively.