Characterization of thermally stable compliant structures with internal fluidic channels

This paper represents a novel method to suppress the thermal effects of flexure mechanism-based nanopositioning system by fluid (air or water) flow under certain pressure conditions through the internal fluidic channels of the compliant structure. The nanopositioning system made of stainless steel was additively manufactured, and the rectangular fluidic channels were formed on each side of the double compound type flexure mechanism-based compliant structure. The motion behavior was characterized by measuring the stiffness and frequency responses of the compliant structure with the hammering test while filling compressed air or the water through the fluidic channels. The thermal behavior was characterized by measuring the temperature distribution over the compliant structure and thermal displacement under the various compressed air pressure and water flow-rate conditions. Dynamic behaviors of the nanopositioning system under various fluid-fed conditions were also characterized by the Finite Element Method and were validated with experimental results. As a result, the compressed air- or water-fed mechanisms have the following characteristics: (1) the damping may increase when the fluid exists in the channels, (2) the compressed air-fed mechanism can move the stage with nanometer precision with fast response time, and (3) the media filled in the fluidic channels significantly lower the temperature increase and reduce thermal displacement error. Interestingly, two-fluid flows of the compressed air and water showed a similar tendency in suppressing the temperature increase. The proposed method is expected to meet the increasing needs for nanometer motion accuracies and the efforts achieving high precision in the thermally stable environments requiring from semiconductor industries and precision machine tool industries.