Microactuators

Microactuators are devices that convert energy into motion at small scales, typically yielding displacements from sub-micrometers to a few tens of micrometers and forces in the micro- to milli-Newton range. They are commonly used in MEMS and other microsystem technologies to provide integrated actuation within electronic or optical components.

Common actuation principles include electrostatic (comb-drive or parallel-plate) actuators, which are fast and power-efficient but offer limited stroke; piezoelectric and ferroelectric actuators (such as PZT) that deliver high forces and precise positioning but require relatively high voltages and exhibit hysteresis; magnetic actuators with micro-coils and magnets; thermal or electrothermal actuators based on differential expansion or phase-change materials; and dielectric elastomer or shape-memory devices for larger strains, typically with slower response and higher power consumption. Each mechanism trades off force, stroke, speed, voltage, and integration complexity.

Manufacture relies on MEMS processes, including surface and bulk micromachining and thin-film deposition. Materials span silicon, silicon-on-insulator, ceramics, piezoelectric films, and magnetic alloys. Packaging choices and environmental control are important to mitigate stiction, wear, temperature sensitivity, and parasitic effects.

Applications include microvalves and micropumps for microfluidics, optical and RF switches, micro-positioning stages, AFM probes, micro-grippers for biomedical work, and compact tactile or haptic devices in robotics. Performance is described by stroke, force, bandwidth, power, reliability, and integration with sensing and control.

Challenges include scaling effects, hysteresis and nonlinearities in piezoelectric devices, fatigue, temperature dependence, and packaging. Ongoing research seeks higher bandwidth, lower power, and more robust monolithic integration with CMOS and other subsystem technologies.