| 摘要 |
PURPOSE: To obtain a fluid density by providing a means for vibrating a structure body in a fluid and a means for detecting the characteristics of vibration and thus measuring the characteristics of the vibration of the structure body. CONSTITUTION: A rectangular tube 11 that is 200μm long, 100μm wide, and 400μm deep is formed, for example, on a silicon substrate 12 by anisotropic etching and a beam 13 is arranged, as a vibration structure body, at the edge part at the opposite side of an open edge. Also, a drive force for driving the structure body is developed optically, themally, or electrostatically, and at the same time the amplitude of vibration is measured from the capacity change of piezoelectric zinc oxide or that between the edge parts of the beam 13. Then, a frequency for measuring amplitude is selected to give the maximum distinction between the effect of density and that of viscosity and a gas density is obtained from the amplitude of vibration while preventing sensitivity relatively to viscosity or molecular mass.
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