Cerebral blood flow sensor with in situ temperature and thermal conductivity compensation

A micromachined blood flow sensor with in situ tissue temperature and thermal conductivity compensation was developed for the continuous and quantitative measurement of intraparenchymal regional cerebral blood flow. The flow sensor operates in a constant-temperature mode and employs a periodic heating and cooling technique. Thermal conductivity compensation is realized by sampling the peak current outputs at the beginning of the heating period and the baseline temperature variation during the heating period is compensated by an integrated temperature sensor. This approach provides highly reliable data with MEMS-based thin film sensors. It achieves sensitivity of 1.467 mV/ml/100gram-min in the linear range from 0 to 160 ml/100gram-min.