Research Status and Development Trend of Magnetic Fluid Micro-differential Pressure Sensor

As a nano-scale composite functional material, the basic structure of the new magnetic fluid is to uniformly disperse the magnetic solid particles adsorbed with surfactants into the base liquid, thus forming a stable colloid system with high dispersion. Magnetic fluid can exist stably for a long time even under the action of gravity field, magnetic field and electric field without precipitation and separation. This kind of magnetic fluid has both magnetic and liquid fluidity under the action of magnetic field, so it has great potential for the application of magnetic fluid in the field of sensors. This paper mainly analyzes the research achievements of magnetic fluid in the neighborhood of micro-differential pressure sensor at home and abroad in recent years, and introduces the working principle and latest research progress of magnetic fluid sensor. Thus, making use of the special properties of magnetic fluid, it is applied to some problems in the field of micro-pressure difference sensor and the research direction of magnetic fluid micro-pressure difference sensor in the future.

Capacitance pressure sensor with S-type electrode for improved sensitivity

This paper aims at designing a differential pressure sensor. The objective of the work is to design and fabricate the electrodes of a capacitive pressure sensor, so as to measure absolute and differential pressure accurately with improved sensitivity. In place of conventional parallel plate diaphragm, S-type electrodes are proposed in the present work. The work comprises of study of the proposed design in terms of a mathematical model, input-output behavior along with detailed analysis of pressure distribution pattern. Output capacitance obtained for changes in pressure is converted to voltage with the suitable signal conditioning circuit and data acquisition system to acquire the signal on to a PC. A neural network model is designed to compensate the nonlinearities present in the sensor output. Input-output characteristics of the designed sensor shows an improved response as compared with existing pressure sensors.

Identification of Axial and Radial Impacts for Pneumatic Artificial Muscles in Static and Dynamic Processes Based on Autocorrelations of Differential Pressure Signals

Since the pneumatic artificial muscle is usually employed to actuate the robot, it is inevitable that it will collide with obstacles and/or other objects such that there will be impacts. The typical impacts include the axial and radial ones. This paper detects these two kinds of impact by a designed differential pressure measurement system, and achieves the goal of identifying them by the autocorrelations of their differential pressure signals in both static and dynamic processes, which are the two main work processes of the pneumatic artificial muscle. In detail, first we design an experiment scheme by connecting the pneumatic artificial muscle to the differential pressure sensor through two pressure tubes; then the axial and radial impact signals are acquired via the impact experiments under different work conditions (impact strength, internal pressure, load, and impact position); finally, the identification of the axial and radial impact signals are achieved based on the autocorrelation technique with a well-selected threshold. The experiments illustrate the effectiveness of the whole method.