Abstract: A sensor assembly and a method of manufacturing a sensor assembly. The sensor comprising a gas sensor comprising a gas sensing area, and a package comprising one or more walls, where the walls define a volume accommodating the gas sensor and where one of the walls comprises an aperture defining an inlet for the package. The package comprises a deflecting surface within the volume wherein, in use, the deflecting surface is configured to convey gas molecules towards the gas sensing area.

Abstract: An environmental sensor assembly comprising: a package; and an environmental sensor disposed in the package, the environmental sensor comprising a sensing region and a reference region; wherein the package comprises one or more inlets arranged symmetrically with respect to the sensing region and the reference region; and wherein the sensing region is in fluid communication with an external environment through the one or more inlets. A method of manufacturing an environmental sensor assembly is also described.

Abstract: A thermal conductivity sensor for measuring a concentration of a gas, the sensor comprising: a substrate portion; an intermediate layer disposed on the substrate portion; a semiconductor layer disposed on the intermediate layer, and a dielectric layer comprising a dielectric membrane, the dielectric membrane provided with a heater; wherein the dielectric membrane is located over a gap, the gap being located in the semiconductor layer. Methods for manufacturing a thermal conductivity sensor are also described.

Abstract: A thermal conductivity sensor for measuring a concentration of a gas, the sensor comprising: a substrate portion; a dielectric layer comprising a dielectric membrane, wherein the dielectric membrane is provided with a heater; a first gap between the substrate portion and the dielectric membrane wherein the primary dielectric membrane is located above the first primary gap; and a micro-machined cap layer; a second gap located between the cap layer and the dielectric membrane. A method of manufacturing a thermal conductivity sensor is also described.