MEMS electrothermal actuator

It relies on the equilibrium between the thermal energy produced by an applied electric current and the heat dissipated into the environment or the substrate.

[10][11] These tools are essential for tasks such as micro assembly, biological cell manipulation, and material characterization, offering advantages such as low driving voltages and easy control.

[20] These actuators are used in applications requiring precise control of temperature and force, such as handling fragile micro-particles and single-cell manipulation.

It consists of two equal slanted beams connected at an apex and anchored to the substrate, forming a single conduction path.

A comprehensive deflection model for this actuator involves solving a transcendental function numerically to determine the tip displacement, influenced by factors like beam length, pre-bending angle, and temperature increase.

Applications include pick-and-place operations for nanomaterials,[28] biological cell manipulation,[29] and RF MEMS switches,[30] where the actuator's stability and high force are advantageous.

Cascaded Chevron actuators enhance displacement further by connecting multiple stages, albeit with increased buckling risk.

[33] These actuators provide significant advantages over other types due to their rectilinear motion, high output force, and low driving voltage, making them suitable for a wide range of precise, small-scale tasks.

[34][35] The bimorph design is a prominent type of electrothermal actuator consisting of two or more layers of different materials with varied coefficients of thermal expansion (CTE).

[38] The deflection mechanism relies on material properties, such as Young’s modulus and CTE mismatch, as well as the thickness ratio of the layers and the beam's geometrical parameters.

For a simple two-layer cantilever, the curvature due to thermal expansion mismatch can be calculated using specific formulas involving temperature change, CTE, width, thickness, and Young’s modulus of each layer.

[44] They are also used in atomic force microscopy (AFM)[45] and scanning probe nanolithography (SPN),[46] offering nanometer-scale resolution imaging and efficient patterning.

However, electrothermal actuators generally have low switching speeds due to the large time constants of thermal processes.