Smart catheter flow sensor for continuous regional cerebral blood flow monitoring

This work reports on development of a novel smart catheter flow sensor (SCF) for continuous monitoring of regional cerebral blood flow (CBF). The SCF employs a periodic heating technique rather than continuous heating and calibrates itself every 5 seconds. This approach ensures zero drift for long-term continuous monitoring and can provide reliable data with MEMS-based thin film sensors. In addition, it uses a 4-wire configuration to eliminate lead wire effect and employs ratiometric measurement to deduce the resistance of SCF. Hence, it is more precise when compared to the bridge-type thermal diffusion flow sensor. The developed SCF has a sensitivity of 2.47mV/ml/min in the range from 0 to 100ml/min with a linear correlation coefficient of R² = 0.9969. It achieves a resolution of 0.5ml/min and an accuracy better than 3ml/min of full scale with both temperature and medium thermal conductivity compensation.