4. Multi-axis accelerometers

The integration of miniature sensors makes it easy to obtain a biaxial sensor on the same chip by integrating two uniaxial cells measuring acceleration in the plane of the chip, or a biaxial cell [17] . However, systems with interdigitated capacitive combs (produced by etching thin layers on the surface), which are used to measure acceleration in the plane of the chip, cannot be used to measure out-of-plane acceleration. It is then necessary to develop a measuring cell for this purpose, which usually results in a different sensitivity along this axis. An example of a two-axis sensor is shown in figure 21 , where the two sensitive cells are clearly visible (inset)...