MEMS Angular Actuator with Thin Piezo Film

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Solution Overview

Problem

Existing MEMS angular actuators face issues with high energy consumption, especially due to high actuation voltages in electrostatic systems, and low actuation speed and large dimensions in bulk piezoelectric systems, limiting their effectiveness.

Innovation Solution

A MEMS angular actuator with a thin-piezoelectric-film design featuring a central portion coupled to a substrate and a peripheral portion with deformable membranes arranged in a spiral shape, where piezoelectric actuators cause upward curving of membranes to rotate bearing structures around the central portion, reducing thickness and increasing efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If electrostatic actuation systems are used in MEMS angular actuators, then the device can be manufactured with MEMS technology, but high actuation voltages (hundreds of volts) are required resulting in high energy consumption

Engineering Contradiction:

ImproveMEMS manufacturing compatibilityVSAvoidenergy consumption

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent changes the actuation voltage parameter from high voltage (electrostatic) to low voltage (piezoelectric film) operation. The thin piezoelectric film generates sufficient mechanical displacement at low voltages, resolving the contradiction between MEMS manufacturing compatibility and high energy consumption by transitioning to a different actuation mechanism that operates efficiently at lower power levels.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure combining thin piezoelectric film with deformable membranes and bearing structures. This composite design enables the actuator to achieve the required mechanical motion through piezoelectric coupling, maintaining MEMS manufacturability while dramatically reducing energy consumption compared to electrostatic actuation.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If bulk piezoelectric actuation systems are used, then low actuation voltage is achieved, but the device dimensions become large with thicknesses of several millimeters

Engineering Contradiction:

Improveenergy consumptionVSAvoidthickness

Core Design Contradiction:

Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent replaces bulk piezoelectric materials with thin piezoelectric films deposited on flexible membranes. This thin-film approach reduces the actuator thickness from millimeter-scale bulk dimensions to micrometer-scale film thickness, while maintaining low-voltage operation and enabling integration within compact MEMS structures.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent transitions from three-dimensional bulk piezoelectric actuators to two-dimensional thin-film piezoelectric structures. By depositing piezoelectric material as thin films on planar membranes, the design achieves low-profile integration suitable for planar MEMS manufacturing processes, dramatically reducing the thickness dimension while preserving actuation functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Use of energy by moving object

If bulk piezoelectric actuation systems are used, then low actuation voltage is achieved, but actuation speed becomes slow

Engineering Contradiction:

Improveenergy consumptionVSAvoidactuation speed

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The patent uses thin piezoelectric films on flexible membranes to achieve rapid actuation. The thin-film structure has lower mass and higher mechanical compliance, enabling faster response times and higher actuation speeds compared to bulky piezoelectric materials, while maintaining low-voltage operation through efficient piezoelectric coupling.

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enables a compact, low-power, high-speed angular actuator with reduced out-of-plane displacement, suitable for optical shutters, improving energy efficiency and actuation speed while maintaining small dimensions.

Implementation Method 1

Each bearing structure has a corresponding piezoelectric actuator associated therewith. The piezoelectric actuators are electrically controllable so as to cause deformation of the corresponding membranes

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS12117605B2Angular piezoelectric actuator for a MEMS shutter and manufacturing method thereof

Publication Date: 2024.10.15 STMICROELECTRONICS SRL

AI summary

A MEMS actuator includes a main body having a central portion, couplable to a substrate, and a peripheral portion suspended over the substrate when the central portion is coupled to the substrate. The peripheral portion has a deformable structure extending around the central portion, and forming successively arranged membranes. The MEMS actuator includes bearing structures and corresponding piezoelectric actuators. The bearing structures are fixed at their top to the deformable structure and laterally delimit corresponding cavities, each having a lateral opening facing the central portion of the main body and closed at the top by a membrane. A fixed part of the membrane is fixed to the underlying bearing structure and a suspended part is laterally offset with respect to the underlying bearing structure. The piezoelectric actuators are controllable to cause deformation of the corresponding membrane and rotation of the bearing structures around the central portion of the main body.