Seesaw accelerometer

A microelectromechanical accelerometer for measuring acceleration in the direction of a z-axis which is perpendicular to an xy-plane defined by a device layer, comprising a mobile first proof mass and a mobile second proof mass formed in the device layer and suspended from one or more fixed parts of the accelerometer by a suspension structure, wherein the first proof mass is adjacent to the second proof mass in the xy-plane, the suspension structure allows the first proof mass to undergo rotation out of the xy-plane about a first rotation axis, and the suspension structure allows the second proof mass to undergo rotation out of the xy-plane about a second rotation axis,

• wherein the first and the second rotation axes are parallel to each other and define an x-direction which is parallel to the first and the second rotation axes and a y-direction which is perpendicular to the x-direction, and the y-coordinate of the center of mass of the first proof mass is greater than the y-coordinate of the first rotation axis, and the y-coordinate of the center of mass of the second proof mass is less than the y-coordinate of the second rotation axis, and the y-coordinate of the first rotation axis is greater than the y-coordinate of the second rotation axis by a nonzero distance D,
• wherein the accelerometer comprises a first counter-electrode and a second counter-electrode which are adjacent to the first proof mass in the z-direction, and the size and geometry of the first counter electrode together with the adjacent edges of the first proof mass define a first measurement region on the first proof mass on a first side of the first rotation axis, and the size and geometry of the second counter electrode together with the adjacent edges of the first proof mass define a second measurement region on the first proof mass on a second side of the first rotation axis,
• wherein the accelerometer comprises a third counter-electrode and a fourth counter-electrode which are adjacent to the second proof mass in the z-direction, and the size and geometry of the third counter electrode together with the adjacent edges of the second proof mass define a third measurement region on the second proof mass on a first side of the second rotation axis, and the size and geometry of the fourth counter electrode together with the adjacent edges of the second proof mass define a fourth measurement region on the second proof mass on a second side of the second rotation axis, and wherein
• the areas and shapes of the first, second, third and fourth measurement regions are all substantially equal in the xy-plane,
• the first measurement region and the second measurement region are substantially reflection-symmetric with respect to the first rotation axis, and
• the third measurement region and the fourth measurement region are substantially reflection-symmetric with respect to the second rotation axis.