A processed silicon wafer containing hundreds of micromechanic pressure sensors. Tweezers are being used to remove faulty sensors, labelled by an automatic test device with a black dot of ink. Micromechanics is the method by which tiny mechanical devices are made by a silicon deposition process similar to that used to manufacture microcircuits. The sensors are made on a substrate, or base, of silicon. The wafer is cut into sections during the process, each of which contains a single device. The wafer is backed with a plastic film to keep the sections together. These pressure sensors are destined for use in a car engine on-board performance monitoring system.