Fibre‐optic Multisensor for Simultaneous Monitoring of Pressure and Composition of Gases

The majority of methods for the optical monitoring of gases can be divided into two main groups. In the first, the intrinsic optical properties of the gas are exploited to sense it. In the second group, an indicator is used to transduce the gas concentration into a measurable optical parameter. Most gas sensors are usually sensitive to only one parameter of the monitored gas. This paper contains a description of a gas multisensor that is suitable for measuring gas concentration and pressure at the same time. It needs a special sensor construction that can measure the mentioned properties in parallel. The essence of this sensor is the double rle of the diaphragm. This means that the diaphragm itself is for sensing the pressure and suitable layer with an immobilised reagent is applied on top of the diaphragm for sensing the concentration of the gas. The sensing method is a fibre guided incident light beam to the diaphragm's surface. The incident beam passes through the concentration‐sensitive layer twice as the diaphragm's surface reflects it. The properties of the reflected beam contain the required information — pressure and concentration — about the measured gas. At the output of the system the reflected light intensity is proportional to pressure and the spectrum is promotional to concentration of gas. The paper describes the design and results in detail.