Research On Electret Rotational Speed Sensor System

With the rapid development of high-speed railway and urban railway,the speed and position detection is becoming more and more important.As a key component of high-speed railway speed and position detection system,rotational speed sensor must work reliably and efficiently.At present,the existing photoelectric and magnetic speed sensors have strict requirements on the environment and are struggling with the several problems,including the vulnerability to external interference,complexity of installation process,short lifespan,poor frequency response and other issues.Electret has been widely utilized in sensor field,due to its ability to maintain long-term charge.This paper studies the preparation process and device of the rotational speed sensor based on the electret,according to the characteristics and practical application of the electret.The results of this research have great value for potential application.The main work of this paper is as follows:1.This studies the fabrication process and measurement principles of the Micro-Electro-Mechanical System?MEMS?-based electret rotational speed sensor.An inorganic electret rotational speed sensor based on the SiO₂/Si3N4/SiO₂ sandwich structure is presented in this paper.It is expected to solve the problems such as existing rotational speed sensor's short life and complicated process.2.In terms of preparation process,the author expounds the process principle and process steps of electret of Silicon oxide/silicon nitride/Silicon oxide?SiO₂/Si3N4/SiO₂?sandwich structure in detail.This method reduces the complexity of structural design and process of the device,which improves the problem that the existing devices are difficult to be integrated and mass produced.With the development trend of miniaturization and integration of sensors in the future.3.The changing process of the electret is explored and tested.The author mainly compares at the principles and methods of several charging methods,and tests the charging performance.The results of test proves that the electret has good capacity of maintaining long-term charge in adverse environment after tunneling charging.In terms of the devices application,operating principle of the electret rotational speed sensor is analyzed,simulated and tested by utilizing the characteristics that electret has the keep-charging ability and can provide stable electric field.The analysis results show that the designed speed sensor can realize the rotational speed detection.The designed inorganic electret rotational speed sensor based on SiO₂/Si3N4/SiO₂ sandwich structure is simple in preparation process,low in cost,small in size,high in resolution and can be applied in any given environment.This device provides new ideas about MEMS rotational speed sensors and has a broad application prospect.