The Design Of Signal Conditioning Circuit Of A New Piezoresistivity Flow Sensor

With development of ocean research and exploiture, we need manufacture many kinds of sensor used in ocean. Flow sensor used in real-time measure is one of these sensors. This thesis is a part of National Natural Science Fund Item named new measure of 3-D instantaneous velocity of ocean current and research of a new sensor. The flow sensor in this item is a non-thermal 3-D flow sensor based on piezoresistivity, it doesn't have disadvantages exited with thermal flow sensor, for example high temperature drift and high power consumption, and disadvantages that most of non-thermal flow sensors cannot measure direction.The thesis mostly tells the design of signal conditioning circuit and system of signal acquisition used in the new 3-D flow sensor. In the beginning, simply introduce all sorts of flow sensors and their developments. Then explain the principle of strain gauge and Resistance Bridge. The thesis analyze detailedly the design of multilevel amplifying circuit, include coupling of circuits, circuit noise analysis, characters analysis, amplifier choice. Then show emulation results in single channel amplifying circuit, schematic document and PCB document of eight channels two-level amplifying circuit. Lastly writing a program with real-time collection, analysis processing and display functions in LabVIEW, use the DAQ to test the PCB, the test show circuit noise is very low, it can satisfy our flow sensor's request.