Accelerometer

A tri-axis accelerometer, comprising:

• a substrate surrounding by a first frame, and including a first conductive-layer thereon;
• a first moveable mass connected to the first frame by a plurality of first elastic members and being capable of moving along both directions parallel and perpendicular to the substrate;
• a plurality of first moveable electrodes extending from an inner side of the first moveable mass;
• is a second frame surrounded by the first moveable electrodes, the second frame defining a plurality of first fixed electrodes extending from an outer side of the second frame toward the first moveable mass;
• each of the first fixed electrode being located between two adjacent first moveable electrodes, and each of the first moveable electrodes being located between two adjacent fixed electrodes;
• a second moveable mass surrounded by the second frame and connected to the second frame by a plurality of second elastic members, the second moveable mass being capable of moving a direction perpendicular to the substrate, the second moveable mass defining a second conductive-layer facing the first conductive-layer on the substrate;
• wherein
• the first fixed electrodes and the first moveable electrodes form a comb capacitor having variable capacitance according to variable overlapped area therebetween;
• and
• the first conductive-layer and the second conductive-layer form a plate capacitor having variable capacitance according to variable distance therebetween.