Paper Title
Design Of Micro Flow Sensor For Slowly Moving Biological Fluids In Smart Catheters

Abstract
his paper reports on a the design and testing of a micro-flow sensor intended for use in implantable ventricular-peritoneal shunts. The detection of flow is based on flexible ferromagnetic flaps whose deflection is detected by ultra-sensitive magnetic (MTJ) sensors. Initial tests of the sensor unveiled significant low-frequency noise (drift) limiting the sensitivity to 1.4 mL/hr. The present study identifies thermal noise as the main source of low-frequency drift. Using thermal compensation it is demonstrated that the drift can be reduced below 3.2 mL per 24-hr. Further improvements are due to use of multiple (four) in-line transducers leading to a sensitivity increase of 7.2 fold. Index Terms - VP shunt; Flow sensor; Thermal noise; MEMS; MTJ sensor