A variety of flow switches, controllers, or meters, as well as the core of leak or bubble detection systems, contain the thermal mass flow sensor. These sensors are utilized for measuring the mass flow of various gases, including oxygen, nitrogen, hydrogen, chlorine, multi-component gases, blast furnace gas, coke oven gas, and flue gas. They are also crucial in compressed air systems, carbon dioxide measurement, argon processes, natural gas applications, biogas measurement, and aeration air in wastewater treatment plants. The mass flow sensor elements with thermal measurement principles measure gas mass flow based on heat transfer principles, eliminating the need for external pressure or temperature compensation. The absence of moving parts ensures long-term reliability and significantly reduces maintenance requirements. Our sensors cause negligible flow restriction, which helps conserve energy within the system. The low energy applied to the sensor allows for safe use with flammable gases like natural gas and hydrogen. Custom flow sensors can be built with physical sensors and can be tested by evaluation kits.