This Air-flow-Sensor processes according to the principle of Hotfilm-Anemometer & uses the cooling effect of the painted air current over the surface of sensor element. Thus the outlet voltage is changed in the same measure like the air- or gas current via the inlet- & outlet openings of sensor casings. Constructed with a thin film-, thermo-isolated bridge structure with heat- & two temperature sensor elements. The bridge structure enables high measuring sensitivity as well as fast response time on air-/gas current over the Chip. Both the temperature sensors with the heating element lying inbetween them, enables the recognition of the direction of the current & the measurement of efficiency. Made up of two Wheatstone-Bridges of existing, passive Element.