MEMS electroscope. Coloured scanning electron micrograph of an electroscope MEMS (microelectromechanical systems) device. MEMS devices are constructed on a microscopic scale using technologies such as wet and dry etching and thin film deposition. Applications include sensors and optical displays. Materials used to construct MEMS devices include silicon and polymers such as plastics. This device is used for indicating the strength of a static electric charge. Magnification: x394, when printed 10 centimetres wide.