Flow Sensor System Research Articles

Self-compensating fiber optic flow sensor system and its field applications.

A self-compensating fiber optic flow sensor system based on the principle of broadband white-light interferometers and cantilever beam bending is described. The fiber optic sensor system uses two fiber ferrule sensors that are bonded on either side of a cantilever beam to measure the flow rate by monitoring the air-gap changes caused by the bending of the cantilever beam. Cross sensitivity of the temperature and pressure dependence of the sensor can be compensated for automatically. The prototype sensor system was constructed, laboratory characterized, and field tested. The results from the field testing have demonstrated high resolution, repeatability, and stability for on-line detection of the flow rates of fluids.

Development of built-in type and noninvasive sensor systems for smart artificial heart.

It is very important to grasp the artificial heart condition and the physiologic conditions for the implantable artificial heart. In our laboratory, a smart artificial heart (SAH) has been proposed and developed. An SAH is an artificial heart with a noninvasive sensor; it is a sensorized and intelligent artificial heart for safe and effective treatment. In this study, the following sensor systems for SAH are described: noninvasive blood temperature sensor system, noninvasive blood pressure sensor system, and noninvasive small blood flow sensor system. These noninvasive sensor systems are integrated and included around the artificial heart to evaluate these sensor systems for SAH by the mockup experiments and the animal experiments. The blood temperature could be measured stably by the temperature sensor system. Aortic pressure was estimated, and sucking condition was detected by the pressure sensor system. The blood flow was measured by the flow meter system within 10% error. As a result of these experiments, we confirmed the effectiveness of the sensor systems for SAH.

A system-level simulation of complex multi-domain microsystems by using analogue hardware description languages

A simulation approach is presented, which permits the simulation of spatially distributed fields with behavioral models of other physical effects and accompanying electronics within a single simulator environment. The final system-level model is a blend of finite-element, analytical, semi-analytical and parametric behavioral models with complex analogue and digital circuit networks. Previously evaluated calculations revealed successful simulation of finite element models with more than 25 000 nodes by using analogue simulators with hardware description language. The relative error of static calculations in comparison with commercial finite element simulators is better than 0.002% and 0.08% for 2D and 3D models, respectively. The results obtained in transient model verification proved the accuracy of the method. The simulation of the flow sensor system, whose functionality is governed by coupled fluidic-thermal-electric domains, is employed to show the feasibility of the method for complex microsystem modeling.

In the flow with MEMS

Presents an overview of MEMS technology where we look at the different micromachining techniques and the CMOS fabrication process. Next we provide general information about flow sensors, including common applications. We will then analyze the structures used for MEMS flow sensors along with their associated CMOS circuits which can integrate the flow sensor into a smart flow-sensor system.

An invasive catheter flow sensor with on-chip CMOS readout electronics for the on-line determination of blood flow

A silicon flow sensor with integrated electronics for invasive blood-flow measurement has been developed and investigated. The flow sensor is based on a silicon-on-insulator SIMOX (separation by implanted oxygen) substrate with a backside etched silicon membrane containing oxide trenches and uses a differential thermal measurement principle. The chosen fabrication process is fully CMOS-compatible. An on-chip switched-capacitor circuitry converts the flow signal into a pulse-width-modulated signal. The device has been tested in a blood-circulation simulator in the flow range 0–101 min −1 within a vessel with a diameter of 2 cm. It has been found to be useful for the observation of time-dependent flow pulses as well as for the determination of the cardiac output. A prototype version of the flow-sensor system has a membrane temperature of less than 2 K above ambient temperature, a total power consumption of 5 mW and shows a pulse-width change from 45 to 25 μs for the flow range 0–101 min −1.