Abstract: The invention concerns sensors (1) for detection of gas, in particular sensors for detection of transcutaneous gas such as CO2, and methods for manufacturing a sensor (1). The sensor (1) comprises at least one radiation source (3) for emitting radiation, at least one detector (4) for detection of radiation emitted by the radiation source (3), and at least one measurement chamber (6) for receiving the sample gas. The radiation source (3), the detector (4), and the measurement chamber (6) are arranged such that at least a part of the radiation propagates along a path passing through the measurement chamber (6). The sensor (1) further comprises a casing (7), wherein the radiation source (3), the detector (4), the measurement chamber (6) are arranged. The sensor (1) has a contact face (8) which is directable towards a measuring site and the sensor (1) has at least one gas-access channel (9) enabling gas to migrate from the contact face (8) into the measurement chamber (6).