Micro-electromechanical device and composite base material used in one micro-electromechanical device

The invention provides a micro-electromechanical device and a composite base material used in one micro-electromechanical device. The micro-electromechanical device comprises a first silicon structure layer and a second silicon structure layer, wherein the second silicon structure layer is fixedly connected with the first silicon structure layer. The first silicon structure layer comprises a rotary rod piece and a first plane, and a first crystal lattice direction and a second crystal lattice direction are defined on the first silicon structure, the Miller index of the first crystal lattice direction is (100), the Miller index of the second crystal lattice direction is (110), the first crystal lattice direction and the second crystal lattice direction are parallel to the first plane, the rod piece has a rotation shaft direction, and the rotation shaft direction is parallel to the first plane and crossed with the second crystal lattice direction. Thereby, torsional rigidity of the rod piece in the micro-electromechanical device can be improved.