Investigation of Dynamic Characteristics of A Blood Pressure Sensor英文电子书.pdfVIP

Investigation of Dynamic Characteristics of A Blood Pressure Sensor Huang xi Medical Electronics and Instrumentation Electrical Engineering and Instrumentation 200554431 Background The understanding of the dynamic properties of a pressure measurement system is important for analyzing the dynamic response of the measured pressure. Errors in the measurement of dynamic pressure might cause serious consequences such as overestimation of pressure gradients across stenotic heart valves. The liquid filled catheter sensor is a hydraulic system. Hydraulic system can represent the characteristics of either distributed or lumped-parameter models in performance. The distributed parameter models are described in that gives an accurate description of the dynamic behavior of the catheter-sensor system. However, the lumped-parameter model is always applied in clinical situation due to its single degree-of-freedom make it easily work with and more accurate. Figure 1. Catheter sensor system Above figure show the physical model of a catheter- sensor system. An increase in pressure at the input of the catheter causes a flow of liquid to the tip from left to right then fill the sensor to express the diaphragm. The deflection of the diaphragm sense pressure and modulate it into the electric signal. A liquid catheter has inertial, frictional, and elastic properties represented by inertance, resistance, and compliance, respectively. Figure 2.Simplified analogous circuit. Figure 2 (a) shows the simplified analogous circuit. The compliance of the sensor has larger compliance of catheter or sensor cavity for a bubble-free, noncompliant catheter. The resistance and in