No abstract

No abstract

A novel and simple technology for making robust three-dimensional (3D) silicon structures with small radii of bending has been developed and investigated. The proposed self-assembly method of bending 3D structures out of plane such that they stay bent without any interlocking braces is based on thermal shrinkage of polyimide in V-grooves. A wide range of bending angles for the permanent out-of-plane rotated structure can be chosen by varying the curing temperature of the polyimide. The relatively large thermal expansion of polyimide makes it possible to use the structure in a dynamic mode useful for compensation of undesired process variations. The proposed technique is compatible with both IC based surface micromachining and batch fabrication. Therefore, structures based on the new polyimide joint have general applications in micromachining and can be used in many new 3D sensors or actuators having detailed features in all three dimensions.For the tested polyimide V-groove joints, static bending angles between 0 • and 200 • have been achieved with a maximum bending angle of 35 • per V-groove. Bending radii smaller than 60 µm for a 30 µm thick out-of-plane rotated silicon plate have been measured. Electrical connections to the assembled structures have been investigated. It has been shown that the aluminium conductors crossing the V-grooves in the polyimide joint are not affected by the out-of-plane rotation.

No abstract

A new micro-robotic conveyance system based on arrays of movable robust silicon legs has been developed and investigated. Motion is achieved by thermal expansion in polyimide joint actuators using electrical heating. Successful experiments on moving and rotating flat objects in the millimeter range have been performed with high load capacity. The conveyer consists of a 15×5 mm2 chip having 12 silicon legs, each with a length of 500 µm. The maximum load conveyed on the structure was 3500 mg. Both transverse and rotational movements have been demonstrated experimentally. Conveyance velocities up to 12 mm s-1 have been measured. Accelerated lifetime measurements demonstrate the long-term stability of the actuators. The functionality of the polyimide joint actuators is unaffected after more than 2×108 load cycles.