TABLE OF CONTENTS The application of MEMS to the measurement of pressure is a mature application of micromachined silicon mechanical sensors, and devices have been around for more than 30 years. It is without doubt one of the most successful application areas, accounting for a large portion of the MEMS market. Pressure sensors have been developed that use a wide range of sensing techniques, from the most common piezoresistive type to high-performance resonant pressure sensors.
The suitability of MEMS to mass-produced miniature high-performance sensors at low cost has opened up a wide range of applications. Examples include automotive manifold air and tire pressure, industrial process control, hydraulic systems, microphones, and intravenous blood pressure measurement. Normally the pressurized medium is a fluid, and pressure can also be used to indirectly determine a range of other measurands such as flow in a pipe, volume of liquid inside a tank, altitude, and air speed. Many of these applications will be highlighted in this chapter, demonstrating MEMS solutions to a diverse range of requirements.
This chapter will first introduce the basic physics of pressure sensing and discuss the influence of factors such as static and dynamic effects as well as media compressibility. Following that is a section on the specifications of pressure sensors, which serves to introduce the terms used and the characteristics desired in a pressure sensor. Before describing the many MEMS developments that have occurred in the field of pressure sensing, there is brief discussion on traditional pressure sensors and diaphragm design. The...
