Liquid-on-beam structure for gas sensing

This paper reports an approach for gas sensing, using liquid-on-beam structure. The key here is a piezoresistive beam was designed at the (lower) interface of liquid and air. Consider gas molecules adhere to the upper surface of liquid, the liquid's surface tension changes, resulting in the deformation of the beam. Since a small amount of gas molecule adhesion to the liquid surface can change the surface tension, this sensing method is supposed to be fast and sensitive. The sensor chip in the experiments had the dimensions of 2.5mm × 2.5mm × 0.3mm. To confirm the measuring principle, the liquid in our proposed device were silicone oil (HIVAC-F4) for acetone vapor gas sensing, since the acetone's molecules can change the silicone oil's surface tension. In the demonstration of CO2 gas sensing, ionic liquid ([EMIM][BF4]) were used regarding the selective ability of CO2 gas absorption