Monday, June 18, 2007
Golden Eagle Eyrie (Boise Centre on the Grove)

Development of a Magnetic-Shape-Memory-Based Micro-Accelerometer

Chris Pohl1, Michael Hagler1, Volodymir Chernenko2, Makato Ohtsuka3, and Peter Müllner1. (1) Boise State University, Boise, ID, (2) Institute of Magnetism, Kyiv, Ukraine, (3) Tohoku University, Sendai, Japan

Ni-Mn-Ga magnetic shape-memory alloys tend to undergo a large deformation upon the application of a magnetic field. This deformation is attributed to twin boundary motion in the martensitic phase and is related to a martensitic phase transformation. Efforts to utilize magnetic-field-induced deformation (magnetoplasticity) in sensors and actuators are attracting attention. A micro-accelerometer is being developed, which harnesses the stress induced change in magnetization of Ni-Mn-Ga thin films. Substrate-curvature experiments were carried out with films in the thickness range between 0.5 μm and 3.0 μm. The samples were heated to maximum temperatures of 65ºC and 130ºC. Through design of experiments (DOE) approach, the correlations between film thickness, stress at which the martensitic transformation occurs, the maximum temperature of a thermal cycle, and heating rate, was assessed. The stress at which the martensitic transformation occurs was found to be mostly influenced by the film thickness.