Development of a High Flow-rate/High Operating Frequency Nitinol MEMS Valve

摘要

This paper presents modeling, fabrication, and testing results for a high flow-rate and high frequency Nitinol MEMS valve. ANSYS~R is used to evaluate several Nitinol MEMS valve structural designs with the conclusion that a pentagonal flap with five legs produces higher frequencies and higher strengths without the inherent rotation problem present in standard designs. The Nitinol penta-leg design was fabricated using a novel bi-layer lift-off method. A PMGI polymer layer is initially used as an underlayer while a chromium layer is used as a top layer to produce a non-rotational ortho-planar Nitinol MEMS valve array. This array consists of 65 microvalves with dimensions of lmm in circumference, 50 μm in leg width, and 8.2 μm in Nitinol thickness. Each microvalve covers an orifice of 220 μm in diameter and 500 μm in length and is capable of producing a 150 μm vertical deflection. This Nitinol MEMS valve array was tested for flow-rates in a hydraulic system as a function of applied pressure with a maximum water flow-rate of 16.44 cc/s.