We report on a new low-cost non-dispersive infrared (NDIR) based sensor platform for sub-ppm gas detection. The aim of the sensor platform development was to create a cost-effective, mass-producible and highly accurate device. Due to its sensitivity, the platform is well suitable for measuring and detecting gases like carbon dioxide, methane, dinitrogen oxide, ammonia, ethanol vapour, refrigerants, etc. The sensor is based on the White-cell NDIR approach and realizes a path length of 1.28 m in a device with an external length of less than 10 cm. High mechanical accuracy of the optical system, temperature controlled optics, highly stable electronics and an optimized mirror surfaces allow a detection level as low as 0.007 ppm.