A Novel FSMA Actuation Mechanism for MIcrovalve Applications

Keywords:
FSMA, microvalve, microactuator, thin film transfer

Abstract:
A novel actuation mechanism is presented, which makes use of a microactuator fabricated from a sputtered ferromagnetic shape memory alloy (FSMA) thin film. FSMAs are a new class of material showing a unique combination of high energy densities, thermoelastic and ferromagnetic properties. These properties enable the simultaneous use
of ferromagnetic and shape recovery forces in a single component part. The microactuator consists of a circular arrangement of three FSMA thin film microbridges,
which are placed above a miniature permanent magnet to generate an out-of-plane ferromagnetic force in downward direction. Upon heating the microactuator, a ferromagnetic and a martensite-austenite phase transformation are induced. As a consequence, a shape recovery force occurs in upward direction, while the magnetic force becomes negligible. Thus, by heating and cooling, an antagonistic actuation mechanism is created allowing active motion in two opposite directions combined with a large actuation stroke. This mechanism is implemented in a prototype of a normally closed microvalve. The size is about 11*6*1.7 mm3. The main fabrication technologies are magnetron sputtering, photochemical micromachining and thin film transfer. In the paper, various experiments will be presented to determine optimum operating conditions including infrared microscopy investigations of temperature profiles and force deflection
tests.

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Nanotech 2006 Conference Program Abstract