Detection unit for a gas sensor, gas sensor, system for detecting a plurality of different target gases, and method for detecting a target gas

What is disclosed is a detection unit for a gas sensor, comprising at least one gas-sensitive element (1) comprising at least one gas-sensitive material, the optical properties of which change depending on contact with a target gas. The detection unit is designed for being arranged on a mobile evaluation unit (5) with an image capture unit (6) in order to form a gas sensor, the detection unit having at least one optical lens (2), and the gas-sensitive element (1) and the optical lens (2) being arranged in such a way that the ambient light (U) that penetrates through the gas-sensitive element (1) is able to be imaged by means of the optical lens (2), in particular is able to be imaged onto the image capture unit (6) at the detection unit arranged on the mobile evaluation unit (5).