Thermal flow sensors for MEMS spirometric devices

Sleep-specific respiration disturbances and their coprevalences with basic cardiovascular diseases constitute a supplementary risk for the cardiovascular system and require both urgent diagnostic assessment as well as consistent therapeutic measures. Thus, the need for controlling the breathing of these patients over a long period has become a new focus of interest. Due to its small thermal mass, the micro-machined thermal flow sensor fits the specific requirements in the patient respiration control of high dynamic flow range combined with a fast response time. We present the development of our flow sensor with a special adaptation for spirometric applications. The sensor exhibits a high accuracy, a short response time (<1 ms) and a low power consumption (10 mW). Furthermore, heating structures are added onto the chip to prevent condensation. Hence, it represents an attractive solution for the use of portable equipment for preventive exploration of breathing in home-care applications.