A micromachined silicon electron tunneling sensor

An electron tunneling sensor that takes advantage of the extreme position sensitivity of electron tunneling and the unique properties of micromachined silicon is presented. Anisotropic etchants, such as EDP, are used to create micrometer- and millimeter-scale structures such as single-crystal silicon springs, electrodes, and tunneling tips, which are then incorporated in the sensor. The electrostatic force between a pair of planar electrodes is used to control the separation between the tunneling tip and the surface. The thermal drift, hysteresis, and creep of conventional piezoelectric actuators is thereby avoided. Because the structure is composed entirely of silicon, the usual problems associated with differential thermal expansion in piezoelectric-based tunnel devices are greatly reduced