Active Spectrum, Inc.

California Institute of Technology

Christopher John White

James Robert White

Colin T Elliott

Alexander H Slocum, Jr

Seyed Ali Hajimiri

Michael Roukes

Xiao-Li Feng

Jay W Walker

David T Huang

An instrument and method using electron spin resonance spectrometry for measuring the concentration of airborne soot particles, and the like, that includes continuously passing a sample of exhaust gas through a resonating RF microwave cavity resonator during the application therethrough of a uniform slowly varying uniform magnetic field that is rapidly modulated and measuring the resulting phase modulation or amplitude modulation thereof to derive an electron spin resonance signal that directly senses the concentration of carbon free radicals produced as a result of inefficient combustion of hydrocarbons during operation of the vehicle or boiler. A further invention is the use of this signal for feedback control of the engine or boiler operating parameters to minimize or substantially eliminate particulate matter emissions.

Method of and apparatus for in-situ measurement of soot by electron spin resonance (ESR) spectrometry

Described is a miniature tunable filter, comprising at least two adjacent coaxial-type resonators coupled to one another. Each coaxial-type resonator comprises a metal-coated ceramic dielectric cavity having a tuning rod passage formed therethrough. A tuning rod is inserted through the tuning rod passage, such that the miniature tunable filter is tuned by moving the tuning rod into and out of the tuning rod passage of the ceramic dielectric cavity. A low impedance coaxial section surrounds at least a portion of the tuning rod to create an effective microwave short-circuit at a resonant frequency of the miniature tunable filter, which results in very wide tuning and low insertion loss. In a desired aspect, the tuning rod is a solid metal tuning rod. The combination of a solid metal tuning rod with a ceramic coaxial-type resonator results in high radio frequency power handling.

Miniature tunable filter

A method of and miniaturized apparatus adapted for in-situ measurement of degradation of automotive fluids and the like by micro-electron spin resonance (ESR) spectrometry, wherein the use of a modulated constant magnetic field in an RF resonating variable frequency microwave cavity resonator through which a fluid sample is passed, enables direct detection of molecular changes in such fluid sample resulting from fluid degradation during use.

Method of and apparatus for in-situ measurement of degradation of automotive fluids and the like by micro-electron spin resonance (ESR) spectrometry

Described is an electron spin resonance (ESR) spectrometer comprising a miniaturized radio-frequency (RF) microwave cavity resonator. The miniaturized RF microwave cavity resonator receives a carrier signal from a circulator, modulates the signal path signal, and reflects the carrier signal back to the circulator to amplify the carrier signal prior to demodulation. A mixer receives and demodulates the carrier signal and outputs an audio signal to generate an ESR spectrum for analyzing a chemical composition of a fluid sample. The ESR spectrum represents a magnetic susceptibility of the fluid sample to a magnetic resonance cause variation in a resonant frequency of the miniaturized RF microwave cavity resonator. In a desired aspect, the carrier signal is split into two paths prior to demodulation. The two paths are demodulated by different mixers to produce two separate outputs, an absorption spectrum and a dispersion spectrum.

Method of and apparatus for analysis of the composition of a sample by electron spin resonance (ESR) spectrometry employing carrier suppression

Method and apparatus for in-situ measurement of soot by electron spin resonance (ESR) spectrometry

A miniaturized instrument and method of using electron spin resonance spectrometry for measuring the degradation of lubricating fluids, and the like, that includes continuously passing a sample of such fluid through a resonating RF microwave cavity resonator during the application therethrough of a uniform slowly varying uniform magnetic field that is rapidly modulated and measuring the resulting phase modulation or amplitude modulation thereof to derive an electron spin resonance signal that directly senses the molecular changes in the fluid sample resulting from fluid degradation during operation of the vehicle, such as peroxy radicals in vehicle engine oil and the like.

Method of and apparatus for in-situ measurement of changes in fluid composition by electron spin resonance (ESR) spectrometry

A self-sustaining ultra-high frequency oscillator and method enable the ability to oscillate and output a signal. A balanced bridge circuit is utilized to null an embedding background response. A first vibrating nanoelectromechanical (NEMS) beam resonator is part of one of the branches of the balanced bridge circuit and determines the frequency of the oscillator's output signal. A feedback loop establishes and sets oscillation conditions of the oscillator's signal. Further, the feedback loop connects an output of the first resonator to an input of the balanced bridge circuit.

Ultra-high frequency self-sustaining oscillators, coupled oscillators, voltage-controlled oscillators, and oscillator arrays based on vibrating nanoelectromechanical resonators

The present invention relates generally to frequency standards. More specifically, the present invention relates to a method and apparatus for solid-state atomic frequency standard based on the hyperfine spectrum of paramagnetic dopants in solids.

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Palo Alto, CA, United States of America

Christopher John White