Thermal buckling of eccentric microfabricated nickel beams as temperature regulated nonlinear actuators for flow control

The design, fabrication and testing of micromachined nickel beams buckling under thermal loading is presented in this paper. The focus is on characterizing design parameters important to the implementation of electroplated nickel beams as the actuation mechanism in thermally adaptive microvalves for self-regulated MEMS cooling schemes. Nondimensional design curves of the thermal buckling phenomena have been analytically developed and validated with test results from electroplated nickel beams with slight eccentricities. Highly nonlinear deflection versus temperature curves were predicted by a closed form model and match well with experimental measurements. Buckling deflections of more than 50 mu m were achieved at actuation temperatures under 100 degrees C. The fabrication process for suspended nickel beams is also presented, along with fabrication issues that impact the actuation capabilities of the beams. (c) 2006 Elsevier B.V. All rights reserved.