Seesaw accelerometer

A microelectromechanical accelerometer for measuring acceleration in a 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 a y-coordinate of a center of mass of the first proof mass is greater than a y-coordinate of the first rotation axis, and a y-coordinate of a center of mass of the second proof mass is less than a 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 a size and geometry of the first counter electrode together with 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 a 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 a size and geometry of the third counter electrode together with 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 a 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, wherein
• 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,
• wherein the distance in the y-direction from the first rotation axis to a border of the first measurement region is nonzero,
• wherein the distance in the y-direction from the second rotation axis to a border of the third measurement region is equal to the distance in the y-direction from the first rotation axis to the border of the first measurement region, and
• wherein a first end of the first proof mass has a first y-coordinate and a second end of the first proof mass has a second y-coordinate, and the first y-coordinate differs from the second y-coordinate, and a first end of the second proof mass has a third y-coordinate and a second end of the second proof mass has a fourth y-coordinate, and the third y-coordinate differs from the fourth y-coordinate, and the first measurement region extends substantially to the first y-coordinate, and the second measurement region extends substantially to the second y-coordinate, and the third measurement region extends substantially to the third y-coordinate, and wherein the fourth measurement region extends substantially to the fourth y-coordinate.