US Patent 8487389 Uniaxial acceleration sensor

One-dimensional acceleration sensor includes: a semiconductor substrate having a constant thickness; parallel second through trenches through the substrate defining a flexible beam therebetween, having width significantly smaller than thickness; four piezo resistors formed at four corner regions of the flexible beam; first through trench through the substrate, continuous with ends of the first through trenches to define a weight continuous with one end of the flexible beam, including a pair of symmetrical first portions sandwiching the flexible beam and a second portion coupling the first portions and one end of the flexible beam, and having a center of gravity at an intermediate position on a longitudinal center line of the flexible beam; and one-layer wirings formed above the flexible beam, serially connecting piezo resistors at a same edge, and leading interconnection points generally along a longitudinal direction of the flexible beam.