Sierra Instruments, Inc.

Other

David Michael Korpi

John George Olin

Donald I Ross

The subject invention provides improved means to measure mass collected on a sample collection surface in real time. A resonant structure is used as the 'scale' to determine the mass in real time. The invention employs a membrane, or collection substrate, on the end of a resonant structure resonating in the longitudinal direction. A structure resonating in the longitudinal mode offers a considerably higher resonant frequency than the same structure in the bending mode. The higher the resonant frequency, the more resolution in the frequency of oscillation is available to determine the mass of the collection surface or membrane. The present invention implements this attribute in connection with such a structure.

Longitudinal resonating mode inertial mass sensing systems

A low tare weight filter system is disclosed. The low weight makes the system especially advantageous for use in inertial microbalance instrumentation where small variations in mass must be accounted for to deliver accurate results. Moreover, the assembly is constructed to permit the filter collector to flex and stretch over a complimentary body incorporated in a filter support base and securely fasten to the same. Such use offers further advantages for instrument performance. It insures consistent apposition and long-term stability in the contact between the filter media and its reference surface.

Inertial microbalance filter assembly

The claimed subject matter is directed to a continuous passive temperature, pressure, modulus of elasticity, and force compensated oscillating inertial microbalance and method of using the same. Temperature and/or pressure and/or modulus of elasticity compensation and/or force compensation is achieved by providing two substantially similar oscillating elements wherein only one oscillating element is subjected to the particulate collection means. The other oscillating element is subjected to all other factors but does not include a particulate collection means. By taking the difference between the two similar oscillating elements one can substantially remove the undesirable side effects having to do with changing temperature and/or pressure and/or modulus of elasticity. The ratio of the major axis to the minor axis is important to minimize precession of the oscillating elements.

Oscillating Inertial Microbalance and Method of Passive Compensation

A 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.

Method of manufacturing a microbalance

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.

Microbalance with reduced temperature and / or pressure sensitivity

A thermal mass flow rate sensor is made of a resistance temperature detector wire wound around a mandrel. A metal sheath is formed about the mandrel and wire assembly to be in intimate contact with the mandrel and wire assembly. The materials of which the sensor is made are selected such that their co-efficients of thermal expansion are approximately the same.

Thermal mass flow sensor

A method and apparatus for precise measurement and calibration of gas flow rates is described. The apparatus and method employ precision-bored cylinders adapted for operation with ultrasonic transducers under the control of computer subroutines for accomplishing the desired methods.

Method and apparatus for improved flow rate measurement and calibration

A fluid bypass type flowmeter has a main passage which is configurable to various effective diameters by selectably adding pre-defined additional cross-sections comprised of an adjustable laminar flow element located within a bore for fine adjustm=ent of the full-scale range of the flowmeter, and an adjustable restriction secondary passage for crude adjustments of the range of the meter. With adjustment of the flowmeter, all or a selected portion of the flow to be measured can be diverted through the secondary passage, where a flow measuring device is located, thereby allowing the flowmeter to operate at or near its full scale and thereby improving the accuracy of the flowmeter over various ranges of flow rate. A laminar flow element is employed in the main passage so that the pressure drop across the element varies linearly with flow rate and, accordingly, the ratio of diverted to un-diverted flow is a constant ratio even though the flow rate varies. The secondary passage adjustable restriction is also designed to give laminar flow to obtain linearity over flow rate variations.

Wide-range, adjustable flowmeter

An improved mass flowmeter of the type having a primary passage for the fluid whose flow rate is to be measured, a sensor tube which serves as a secondary passage for the fluid and is connected to the primary passage at upstream and downstream locations, and a pair of resistance wire coils surrounding the sensor tube and connected to a bridge circuit in which the resistance differential between the wire coils is proportional to the fluid flow rate. The sensor tube is a straight tube displaced from the primary passage and accessible at its ends for cleaning. The wire coils and the corresponding portion of the sensor tube are surrounded by an evacuated enclosure to prevent convection effects between the adjacent coils, to maximize the response time of the coils to changes in fluid flow rate, and to reduce conduction losses.

Growing community of inventors

Salinas, CA, United States of America

David Michael Korpi