An Innovative and Reliable Wireless Angular Accelerometer Made Directly on a Flexible Substrate without Moving Parts

Abstract

Five novel ideas are proposed in this paper to integrate an active RFID tag with a thermal convection angular accelerometer on a flexible substrate, thus the new device becomes a wireless sensor. The first innovative idea is that this device is without any movable parts, so it is very reliable. The second new idea is that it is made on a flexible substrate, such as plastic or polyimide, the thermal conductivity of the flexible substrate is much lower than silicon, and thus it can save more power and very useful for mobile operation. The third new idea is to apply xenon gas in the chamber to conduct the heat instead of the traditional carbon dioxide, so no oxidation and performance degradation effects will be produced on the heater and thermal sensors. The fourth new idea is to integrate with an active RFID tag on the same substrate, thus the device becomes a more useful wireless angular acceleration sensor. The final new idea is to apply a hemispherical chamber instead of the conventional rectangular one. From the simulation results one can see it is a good idea to apply a non-floating type angular accelerometer with a hemispherical chamber, the sensitivity performance is the best (395K/(rad/sec2)), and the response speed (693μs) is also comparable to the traditional one by using a floating type with a rectangular chamber (593μs). In summary, from the considerations of reliability, cost and performance, the non-floating type angular accelerometer with hemispherical chamber is a better choice.