Design and fabrication of a current-pulse-excited bistable magnetic microactuator

In this paper, the design and fabrication of a current-pulse-excited bistable magnetic microactuator is presented. The microactuator consists of a plane magnetic conductor with two pole pieces, a flux-conducting micro cantilever beam, trip coils and a permanent magnet. The cantilever beam has two stable positions and always keeps in conduct with one of the two poles at standstill. By means of a current pulse in the trip coils, the cantilever beam will be excited and switch from one stable position to the other. The microactuator with magnetic conductor size of 6 mmX7 mmX0.1 mm as well as cantilever beam size of 3.8 mmX0.1 mmX0.1 mm is fabricated using repeated UV lithography, electroplating of Ni-Fe alloy using resist micromoulding as well as sacrificial layer etching. A current pulse with an amplitude of 1.25 A and duration of 0.3 ms is required on 60 turns of coils to excite the switching of the cantilever. The switching distance of the cantilever in the air gaps is 100 mu m and the force on the beam in the air gaps is about 5 mN. This actuator can be used as a microrelay or microgripper. With a total length of 4.5 mm, a contact force of about 0.25 mN can be reached on the tip of the beam.