American Research Corporation of Virginia

Eclipse Energy Systems, Inc.

Other

American Research Corporation

Howard P Groger

Russell J Churchill

K Peter Lo

Shufang Luo

Martin Weiss

Raymond Thomas Westfall

Peter Lo

Usha Varshney

Myron T Coolbaugh

William F Sullivan

Jesse J Brown

Lawrence H Decker

Bruce L Thomas

John W Raymonda

Roger L Reynolds

Frederick A Kamke

John A Neal

James Kelsch

Peter Zory

Shu-Fang Luo

Howard J Moses

James M Sloan

Douglas J Jaeger

Nicholas V Nechitailo

James M Glass

Chong T Ng

An iono-refractive structure that includes one or more ion insertion layers having a real portion and an imaginary portion of the dielectric constant is provided. While both the real portion and the imaginary portion of the dielectric constant change, the change in the imaginary portion is less than the change in the real portion at the wavelength of interest or at the operational wavelength. The iono-refractive structure may be suitable for the fabrication of or integration with tunable optical filters, wavelength-selective optical elements, active modulated interferometers, optical phase shifters, optical phased array beam steering, optical phased array beam tracking, tunable optical filters, sensors, variable lenses, tunable diffraction gratings, and other optical components.

Apparatus and methods for modulating refractive index

A highly-sensitive, rapid response fluorescent probe is based on the affinity of a polymer matrix for an analyte of interest. The probe includes a polymer matrix and a dye immobilized in the matrix. The polymer matrix has an affinity for an analyte of interest and the dye has little or no sensitivity to the analyte of interest when excited by an excitation source in a free state but has significant sensitivity to the analyte of interest when excited by the excitation source when immobilized in the matrix. Sensors incorporating the polymer/fluorophore probes of the present invention have the sensitivity and rapid response needed for detection of chemical agent and biological materials. Sensors using the probes provide sensitivity to Sarin at several hundred parts per trillion in one second or less. That is a notable advance over state-of-the-art detectors that require preconcentration steps, which in turn restrict response times to one minute or more. A wide-range of near-infrared excitable fluorophores are used as sensitive probes for analytes not detectable when the fluorophores are outside the polymer matrix. The present sensors provide early warning of the presence of toxic chemicals, provides for on-line analysis of trace materials in chemical and biological processing operations and biomedical processing operations, and provides for effective biomedical and environmental monitoring.

Fluorescent probes based on the affinity of a polymer matrix for an analyte of interest

An instrument for total internal reflection fluorescence spectroscopy having modular probe that inexpensively monitors vapors and liquid-phase analytes under field conditions is described. The system is particularly helpful in evaluating multiple analytes using the fluorescence of a material immobilized in a thin sorbent polymer coating. At the same time, the system is capable of monitoring trace quantities of analyte using a fluorescence-read immunological reaction. The device includes a diode laser source, a shaped optical element (which may be as simple as a microscope slide), and one or more amplified photodiode detectors. The shaped optical element propagates light from the diode laser in a series of internally reflective bounces.

Modular probe for total internal reflection fluorescence spectroscopy

The present sensor allows the user of any diode laser structure to be employed to provide sensitive chemical and biological detector. A diode laser electrochemical sensor is described in U.S. Pat. No. 5,591,407 &ldquo;Laser Diode Sensor&rdquo;. The present invention surpasses the capabilities of those sensors by measuring changes in the output power, output spectral characteristics or output signal auto-correlation function to detect the presence of chemical or biological films within the sensitive region.

Diode laser electrochemical sensor for detecting chemical and biological analytes

An optical fiber fluorescence sensor system capable of compensating fiber bending loss is provided. The system uses a modulated light-emitting diode and digital-signal processing chips to enhance the measurement of fluorescence signals. A fiber-optic oxygen sensor system suitable for measuring oxygen levels in gas and in aqueous media is provided. The system alleviates fiber bending loss. Detection of the signal-to-noise ratio of the system which exceeds 30 dB is done by using inexpensive components.

Loss compensation using digital-signal processing in fiber-optic fluorescence sensors

Optical chemical probes have layers of anionic and cationic polyelectrolytes and one or more dyes incorporated into these layers. The probes are placed into the medium and the dye or dyes react in the presence of the corresponding chemical. Color changes may be observed manually or by a photo detector. A light source may be employed to increase the optical signal received from the probe. Further, a waveguide may be used to trap multiple optical signals. The invention is used for chemical analysis.

Optical chemical sensor based on multilayer self-assembled thin film

The vibration and electrical characterization of a piezoelectric tactor actuator is described. The actuator is a rectangular laminated flat plate with two opposite sides simply supported and two others free. Under an axial compression from the supports, the plate deforms into a stressed shallow shell. Electrical high frequency harmonic signals within relatively low-frequency bursts are applied to the piezoelectric layers. Depending on the axial compression and pre-deflection, frequency and magnitude of electrical input, the tunable actuator exhibits frequency/mode-controlled high-force over large area vibrations with intense displacement jumps. A single-degree-of-freedom model and simplified 1-D models are provided. The tactor provides efficient conversion of electrical energy into mechanical.

Piezoceramic vibrotactile transducer based on pre-compressed arch

A-compact, diode laser-based sensor has applications in biological and chemical analysis. Unlike existing optical waveguide-based sensors, no external coupling to external optical fibers or waveguides is required to perform optical chemical, immunological or nucleic acid-based assay or to detect the presence of toxic or otherwise important chemicals. The sensor includes a surface-sensitive diode laser having a substrate layer, an n-contact layer positioned on a bottom surface of the substrate, an n-clad layer overlying the top surface of the substrate, a first guide layer overlying the n-clad layer, a quantum well layer overlying the first guide layer, a second guide layer overlying the first quantum well layer, a p-clad layer overlying the second guided layer and a p-doped cap layer overlying the p-clad layer. A pair of electrodes separated by a surface-sensitive region is positioned on the cap layer. The surface active region includes an oxide layer grown on the thick cap layer and an absorbing or non-absorbing film deposited on the oxide layer. For internal reflection, inorganic material coatings are applied to end facets or Bragg reflectors are etched in the cap layer. Detectors are positioned proximate the diode laser for detecting changes in film thickness or refractive index, absorption or other optical properties resulting from film deposition, surface reactions such as immunological or ion-exchange reactions, or other detectable processes.

Diode laser-based chemical and biological sensor

An apparatus and its accompanying method measures fluorescence decay, fluorescence amplitude and fluorescence polarization. The instrument includes a light emitting diode or laser diode light source, an amplified photodiode detector, and electronics and software for calculating the phase of the fluorescence from the computed inner product of the scattering and fluorescence signals. The electronics for measuring fluorescence decay includes two signal synthesizers, two downconverters, a simultaneously sampling analog-to-digital converter and means for calculating the inner product of the downconverted waveforms. A signal source, preferably a direct digital synthesizer, is used in combination with a digital-to-analog converter to provide a controllable output signal. That signal drives a modulatable light source, which is a light emitting diode, a laser diode or a combination of the two. Excitation light from the light source excites the sample fluorophore which is immobilized in a solid material. Fluorescence is detected using an amplified photodiode. The received signal is downconverted using a pair of mixers. The downconverted signals are digitized and stored. Preferably, the signals are digitized using a two-channel synchronous analog-to-digital converter controlled by a digital signal processor. Data from each channel are multiplied and summed to provide the inner product.

Fluorescence decay measurement by calculation of inner product

Fluorescence measuring methods and apparatus use planar optical waveguides to excite fluorescence in the evanescent field of the waveguides and photodetectors to sense the fluorescence produced. Chemically sensitive fluorophores are bound to the evanescent regions of the planar optical waveguides. Substrates support the waveguides. Photodetectors, positioned in the substrates with fields of view normal to the waveguides, detect the fluorescence. Wavelength-selective material coating surfaces of the photodetectors allow fluorescence to be detected while restricting entry of light at the excitation wavelengths. The photodetectors have high aspect ratios for detection of fluorescence generated by the optical waveguides. Preferably, the photodetectors are closely coupled to the fluorescence generated in the evanescent field of the waveguide. In alternative embodiments, lightguides near the waveguides direct fluorescence from the plane of the waveguides for transmission by integrated optical fibers to remote sensors. For chemical detection and analysis, energy is introduced to an edge of the waveguide. The edges are coated to reflect the energizing energy throughout the waveguide. The energy excites the chemically sensitive fluorophore film positioned on the waveguide. Inexpensive photodetectors without expensive photo-multipliers are mounted in substrates beneath the waveguides or at ends of lightguides extending from the substrates for detecting fluorescence.

Method of fluorescence analysis comprising evanescent wave excitation

A highly sensitive surface plasmon waveguide sensor monitors the refractive index and thickness of thin adsorbed films. The sensor includes an optical waveguide formed by ion-exchange in a glass substrate, by selective densification of substrate material or by the incorporation of high refractive index materials during deposition of a dielectric layer. Two dielectric thin films are deposited on top of the waveguide. The layer closest to the waveguide has a lower refractive index than the guiding layer to form a buffer layer. The second dielectric layer, or tuning layer, has a higher refractive index. The tuning and buffer layers allow optimization of the resonance wavelength, full-width half maximum of the resonance wavelength range and amplitude of the resonance. The tuning layer is coated with a thin metallic layer, to effect surface plasmon resonance, such as gold, silver, aluminum or one or more semiconducting materials. Alternatively the optical waveguide is coated with the buffer layer and the thin metal layer. The tuning layer and a second buffer layer are deposited on top of the metallic layer. Light is introduced to the waveguide and interaction between the light and the thin metal layer results in attenuation of the TM polarization. The ratio of the TM and TE polarization intensities is monitored by a polarization beam splitter. The relatively unchanged TE polarization intensity serves as an integral reference for the sensor. The sensor has numerous applications in the environmental and biomedical fields.

Chemical detector employing surface plasmon resonance excited using an

A chemical sensor uses a semiconductor diode laser having a surface active region. A laser structure, including an active layer, a cladding layer, a barrier layer and a grating layer, is constructed on a substrate. A contact layer is deposited on a surface of the laser structure. One or more electrodes are positioned on the contact layer. A segmented electrode has a first contact pad, a second contact pad, and a surface active region between the first and second pads. A surface active region is created between the two electrodes. The tail of the lasing signal interacts with surface features of the diode laser or with chemical materials or probes in contact with the surface of the diode laser or in contact with coatings on the surface of the diode laser. Chemical changes in the ambient environment induce changes in the laser signal. The modified laser signal output is detected by a detector region integral with or separated from the laser structure. The laser diode sensor has applications in fields involving chemical sensing and identification, including automotive, environmental and medical fields.

Laser diode sensor

The present invention is a new electronic memory-assist device which can be used to remind an individual when it is time to take a prescribed medicine. The invention uses complementary metal-oxide semiconductor technology in conjunction with surface-mounted device technology to provide a programmable portable unit. The device has three parts: a body-carried reminder, a local interactive compliance processor and a supervisory unit. The reminder has a portable power supply, microprocessors, software, memory, an alarm, an input key and communication linkage to the compliance processor. The compliance processor has a central processing unit, a pill case, a modem and, possibly, a recharger for the portable power supply. The supervisory unit is connected to the central processing unit remotely by modems. The device operates by providing data to the user through an alarm that it is time to take prescribed medication. The alarm is visual, auditory, tactile or any combination of the three. The alarm is initiated by software controlling microprocessors in the body-carried reminder and the pill case. The alarm is generated by comparison between the current time and times residing in the prescription database. The alarm continues until interrupted by either a request for more time prior to compliance or through reception of a message signifying that medication has been taken. All compliance data is stored in the central processing unit of the compliance processor.

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Gainesville, FL, United States of America

Howard P Groger