A scratch drive actuator (SDA) is a

microelectromechanical system MEMS (micro-electromechanical systems) is the technology of microscopic devices incorporating both electronic and moving parts. MEMS are made up of components between 1 and 100 micrometres in size (i.e., 0.001 to 0.1 mm), and MEMS devices ...

device that converts

electrical energy Electrical energy is the energy transferred as electric charges move between points with different electric potential, that is, as they move across a voltage, potential difference. As electric potential is lost or gained, work is done changing the ...

into one-dimensional motion.

Description

The

actuator An actuator is a machine element, component of a machine that produces force, torque, or Displacement (geometry), displacement, when an electrical, Pneumatics, pneumatic or Hydraulic fluid, hydraulic input is supplied to it in a system (called an ...

component can come in many shapes and sizes, depending on the fabrication method used. It can be visualised as an 'L'. The smaller end is called the 'bushing'. The actuator sits on top of a substrate that has a thin insulating

dielectric In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electric ...

layer on top. A voltage is applied between the actuator and the substrate, and the resulting potential pulls the body of the actuator downwards. When this occurs, the brush is pushed forwards by a small amount, and energy is stored in the strained actuator. When the voltage is removed, the actuator springs back into shape while the bushing remains in its new position. By applying a pulsed voltage, the SDA can be made to move forward. The voltage is usually applied to the actuator by means of a 'tether'. This can consist of a rigid connector or a rail which the SDA follows. The size of an SDA is typically measured on the

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

scale.

References

Actuators Microtechnology Microelectronic and microelectromechanical systems {{materials-sci-stub