This paper presents an improved thermal actuator design, providing high work per unit of chip area. The actuator was developed for high accuracy fibre alignment. This application requires that the fibre tip is moved by pushing close to its end, posing geometric design constraints on the actuator design. The basic structure of the actuator is a parallelogram, consisting of a non-moving base, a bar parallel to the base placed orthogonal to the fibre axis in contact with the fibre, and heater arms and reinforced restraining arms which connect the base and the bar. The heater arms thermally expand when passing a current through them. On either side of the heater arms there is one restraining arm, placed at a slightly different angle with the base and bar than the heater arms. The restraining arms do not heat up, and constrain the motion due to thermal expansion of the heater arms, resulting in a motion of the bar in its longitudinal direction. The performance of this actuator is compared to two well-known alternative thermal actuator configurations. Comparison shows that the improved actuator delivers 15% more work per area, and is therefore considered an attractive alternative solution for purposes such as in-plane optical fibre alignment.
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