M. J. Tudor
S. P. Beeby
Today, an average car utilizes more than fifty sensors, and a luxury car more than one hundred. Of these, one-third are currently based on micromachined sensors  with the proportion expected to increase in the future. Pressure sensors make up a significant proportion of this (around 15% by value) with manifold absolute pressure sensors being ubiquitous and tire and brake control pressure sensors becoming widespread.
Typical under-hood environments may involve temperatures from –40 °C to 1000 °C with thermal cycling, pressures up to 2000 bar, high humidity, salt spray, extreme shock loads, and high levels of vibration. Sensors must last for the lifetime of the car, ...