Microbalance with reduced temperature and / or pressure sensitivity
OwnerDavid Michael Korpiinventor
Life of this patent
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Abstract
22A temperature and/or pressure compensated microbalance is disclosed. Temperature compensation is achieved by applying heat to at least a part of the microbalance, measuring a temperature-dependent variable, and controlling the amount of heat applied to the microbalance to keep the temperature-dependent variable substantially constant. In one embodiment, the heat is applied to the microbalance by passing electrical current through a resistive element provided on or embedded in the oscillating element of the microbalance. Pressure compensation is achieved by taking into account the variation in the mass or density of fluid passing through the microbalance. Various materials and methods of construction are also disclosed, including micro-machining and electroforming.
Claims8
A method of reducing the temperature sensitivity of a microbalance including an elongated elastic element being coupled at one end thereof to a base with the other end thereof being free to oscillate, comprising the steps of:
- applying heat to the elongated elastic element by means of an element that is provided on a surface of the elongated elastic element, embedded in the elongated elastic element, or partially embedded in the elongated elastic element;
- measuring a parameter that is indicative of the temperature of the elongated elastic element;
- and
- controlling the amount of heat applied to the elongated elastic element to maintain the measured parameter substantially constant.
A microbalance comprising:
- a base;
- an oscillating element coupled at one end thereof to the base;
- and
- an element to apply heat to the oscillating element, wherein the element is:
- provided on a surface of the oscillating element;
- embedded in the oscillating element;
- or partially embedded in the oscillating element.
A method of operating a microbalance, the microbalance including a hollow oscillating element having a filter mounted at one end thereof, the method comprising:
- inducing resonance in the oscillating element;
- passing a fluid through the filter and through the oscillating element;
- measuring the resonant frequency of the oscillating element to determine the mass of material captured in or on the filter;
- measuring a parameter of the fluid being drawn through the oscillating element;
- and,
- compensating for the variation in the resonant frequency that has resulted from the variation of the parameter.
Dependencies are inferred from the claim text.