A functional element includes: a substrate; a movable body that includes a movable electrode portion; a support portion that supports the movable body; a first fixed electrode portion that is disposed on the substrate and a portion of which faces a first portion as one of portions of the movable body; a second fixed electrode portion that is disposed on the substrate and a portion of which faces a second portion as the other portion of the movable body; and a third fixed electrode portion that is disposed on the substrate and a portion of which faces the first portion. An opening that faces a region of the substrate between the first fixed electrode portion and the third fixed electrode portion is provided in the movable body, and the width of the opening is equal to or more than the width of the region.

A MEMS inertial sensor includes a supporting structure and an inertial structure. The inertial structure includes at least one inertial mass, an elastic structure, and a stopper structure. The elastic structure is mechanically coupled to the inertial mass and to the supporting structure so as to enable a movement of the inertial mass in a direction parallel to a first direction, when the supporting structure is subjected to an acceleration parallel to the first direction. The stopper structure is fixed with respect to the supporting structure and includes at least one primary stopper element and one secondary stopper element. If the acceleration exceeds a first threshold value, the inertial mass abuts against the primary stopper element and subsequently rotates about an axis of rotation defined by the primary stopper element. If the acceleration exceeds a second threshold value, rotation of the inertial mass terminates when the inertial mass abuts against the secondary stopper element.

In some embodiments, a sensor includes a microelectromechanical system (MEMS) structure, a cover, and a bump stop. The MEMS structure is configured to move responsive to electromechanical stimuli. The cover is positioned on the MEMS structure. The cover is configured to mechanically protect the MEMS structure. The bump stop is disposed on a substrate and the bump stop is configured to stop the MEMS structure from moving beyond a certain point. The bump stop is further configured to stop the MEMS structure from making physical contact with the substrate. Moreover, the cover is configured to apply a force to the MEMS structure responsive to a voltage being applied to the cover.

A microelectromechanical device includes a semi-flexible proof-mass comprising a primary part, a secondary part and a stiff spring suspending the primary part and the secondary part. The spring causes the parts to move as a single entity when the device is in its normal range. A first stopper structure stops the primary part. The proof-mass is configured to deform through deflection of the spring, when the device is subjected to a shock having a force that is beyond the normal operation range. While the shock causes motion of the proof-mass in one direction along an axis of movement, the spring is configured to cause a restoring force causing the secondary part of the proof-mass to be driven into a restoring motion in a direction opposite to motion along an axis caused by the shock. Momentum of the secondary part causes the primary part to dislodge from the first stopper structure.

A physical quantity sensor includes a substrate that has a first fixed electrode and a movable body that has a first mass portion facing the first fixed electrode. The first mass portion includes a first region, and a second region farther from the rotation axis than the first region, a first through-hole group is provided in the first region, and a second through-hole group is provided in the second region, and the movable body has a first surface on a substrate side, and a second surface. The first surface of the first mass portion is provided with a step or a slope such that a first gap distance of a first gap between the first mass portion and the first fixed electrode in the first region is smaller than a second gap distance of a second gap between the first mass portion and the first fixed electrode in the second region. A depth of through-holes of the first through-hole group and the second through-hole group is smaller than a maximum thickness of the movable body.

A MEMS device includes at least one proof mass, the at least one proof mass is capable of moving to contact at least one target structure. The MEMS device further includes at least one elastic bump stop coupled to the proof mass and situated at a first distance from the target structure. The MEMS device additionally includes at least one secondary bump stop situated at a second distance from the target structure, wherein the second distance is greater than the first distance, and further wherein the at least one elastic bump stop moves to reduce the first distance when a shock is applied.

An inertial structure is elastically coupled through a first elastic structure to a supporting structure so as to move along a sensing axis as a function of a quantity to be detected. The inertial structure includes first and second inertial masses which are elastically coupled together by a second elastic structure to enable movement of the second inertial mass along the sensing axis. The first elastic structure has a lower elastic constant than the second elastic structure so that, in presence of the quantity to be detected, the inertial structure moves in a sensing direction until the first inertial mass stops against a stop structure and the second elastic mass can move further in the sensing direction. Once the quantity to be detected ends, the second inertial mass moves in a direction opposite to the sensing direction and detaches the first inertial mass from the stop structure.

A physical quantity detection element includes: a substrate; first and second fixed electrode portions on the substrate; a movable body on the upper portion of the substrate; and a beam on the movable body, the movable body includes a first movable body on a first side of the beam, and a second movable body on a second side of the beam, the first movable body includes a first movable electrode portion facing the first fixed electrode portion and a first mass portion disposed in an opposite direction of the beam from the first movable electrode portion, the second movable body includes a second movable electrode portion facing the second fixed electrode portion, a mass of the first movable body is greater than a mass of the second movable body, and a mass of the first mass portion is greater than a mass of the first movable electrode portion.

A micro-electro-mechanical system (MEMS) device and a method of testing a MEMS device. The device includes a MEMS sensor having first and second mobile elements, first and second electrodes arranged to deflect the mobile elements by the application of test voltages, and a differential detector circuit. The device also includes an input multiplexer circuit configured selectively to connect each electrode to a test voltage source to apply a plurality of test voltages to deflect the mobile elements during a test mode. The test voltages comprise a set of monotonically increasing test voltages and a set of monotonically decreasing voltages for performing a C(V) sweep to test for stiction. The device further includes an output multiplexer circuit configured selectively to connect the first mobile element and/or the second mobile element to a single one of the inputs of the detector circuit to detect the deflection of the mobile element.

A method is provided for testing a multi-axis micro-electro-mechanical system (MEMS) acceleration sensor. The method includes applying a first voltage to a first-axis excitation plate to move a first proof mass in contact with a proof mass stop; applying a second voltage to a second-axis excitation plate while maintaining the first voltage to the first-axis excitation plate, to move the first proof mass in a direction orthogonal to the first-axis while in contact with the proof mass stop; applying one or more low voltage excitation signals to the first-axis excitation plate; and detecting if an output voltage of the MEMS device is higher than a threshold voltage.