Accelerometers are very useful devices but conventional accelerometers are usually very expensive so their use is still limited, for example, in automobiles. Recently, bulk-micromachined silicon accelerometers have been demonstrated but they typically have sensitivity and resolution limitation (typically no better than 1 milli-g). A few years ago, a couple of prototype tunneling accelerometers have been demonstrated. They do have much better resolution but they can only be made one by one manually and tedious calibration is necessary. In other words, bulky size, high cost, low throughput, etc. will seriously limit their application if not improved. On the other hand, surface micromachining has recently been developed to fabricate many micromechanical devices such as pin joints, springs, sliders, cranks, gears, etc. It is, therefore, generally believed that such technology can also be used to make microsensors. As a result, it is proposed here that highly sensitive, low cost, small size, accelerometers can be made combining surface micromachining techniques and tunneling mechanism. We proposed to use surface micromachining techniques to integrate a sharp tip, a microspring- mass, and an electrostatical feedback together to function as a tunneling accelerometer. Such an accelerometer is estimated to have a resolution of better than 1 micro-g, which is very competitive with state-of-the-art accelerometers. Such integrated tunneling accelerometer will have very important applications for automobile subsystems such as airbag, autosuspension, and navigation.
