Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g. electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

/pdf/sensor-arrays-for-detecting-analytes-in-fluids-1mw0rzj5oi.pdf

Sensor arrays for detecting analytes in fluids

Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

https://ntrs.nasa.gov/api/citations/20080004160/downloads/20080004160.pdf

Sensors for detecting analytes in fluids

A sensor (Fig 1) for detecting an analyte in a fluid comprising a substrate having a first organic material and a second organic material (21) that has a response to an analyte. The sensor has information storage and processing equipment (Fig 14a), and a fluid delivery appliance. This device compares a response (Fig 13) from the detector with a stored ideal response to detect the presence of analyte. Methods for use for the above system are described where the first organic material and the second organic material are sensed and the analyte is detected. The method provides for a device, which delivers fluid to the sensor and measures the response of the sensor with the detector. Further, the response is compared to a stored ideal response for the analyte to determine the presence of the analyte. In different embodiments, the fluid measured may be a gas, a liquid, or a fluid extracted from a solid.

/pdf/methods-of-use-for-sensor-based-fluid-detection-devices-3yuzdzfl2b.pdf

Methods of use for sensor based fluid detection devices

In an improved amperometric gas sensor, the structure, composition, and electrode potential are adjusted so as to prevent or minimize any unwanted reactivity at the counter and/or reference electrode of any analyte or interfering component of the matrix that may cross over thereto. The sensor is preferably structured so that the product of the analyte reaction at a first working electrode can be reconverted to the original analyte at a counter electrode or at a second working electrode and then reacted again at the first working electrode, with such back-and-forth reactions repeating many times, so as to yield an amplification of the analyte signal.

Chemical sensing apparatus and methods

External modulation is accomplished in a dual waveguide device wherein substantially identical input optical beams are supplied to the waveguides and wherein each waveguide through its electrode is subject to individual, mutually exclusive control. Modulation signals are applied to each waveguide via its separate electrode. Control signals are applied to each waveguide for adjusting the modulation chirp parameter to a desired fixed, non-zero value. Typically, the desired value of the chirp parameter is one which provides the lowest fiber dispersion penalty for the system. Modulated lightwave signals emerging from the waveguides are combined to form a single output signal suitable for transmission over an optical fiber. In one embodiment, Mach-Zehnder interferometer having separately controllable waveguides has its input coupled to a CW laser. Both III-V semiconductor and Ti:LiNbO3 Mach-Zehnder interferometers have been utilized as external modulators in accordance with the principles of the present invention.

Tunable chirp, lightwave modulator for dispersion compensation

A hydrocarbon vapor sensor which is simple and low cost and can easily detect the existence of hydrocarbon vapor. The device is temperature compensated so that a change in resistance due to a change in temperature is avoided and an accurate response is always provided. The sensor can be used in a system in which a number of sensors are provided at various depths to determine whether a leak or a ground spill has occurred.

Hydrocarbon vapor sensor and system

A test system utilizing modulators responsive to signals to be tested positioned between a source of electromagnetic radiation and a sensor with the signal to be tested coupled to the input of the modulators. Preferably the modulators are positioned in optical wave guides with the modulators being electric-field operated devices to prevent any significant loading of the signals to be tested. Disclosed embodiments utilize light as the electromagnetic energy with lithium niobate substrates having titanium diffused therein forming the optical wave guides. Modulators are provided by planar electrodes affixed to the surface of the lithium niobate substrate to change the electric field across the optical waveguide. Coupling is conveniently provided to the wave guides through fiber optic bundles.

Multi-channel test system using optical waveguide modulators

An assembly for protecting a conduit having a core and an axial length, which length is susceptible to being pinched by a structure is disclosed. The conduit includes an insulating coating in surrounding relationship about the core, with the assembly including a semiconductive layer in surrounding relationship about the insulating coating, and a switching layer in surrounding relationship about the semiconductive layer. The semiconductive layer being formed from partially vulcanized ethylene propylene rubber including particles of a conductive element in the form of carbon black, silver, nickel, aluminum or the like. The switching layer is non-conductive in its unstressed state and conductive when pinched such that the switching layer completes a current flow path between the semiconductive layer and either a grounded structure or another conductive layer, which condition may then be detected.

Assembly for detecting and locating cable pinching

A non-contact DC current sensor has a housing in which a pair of cantilevered compliant armatures are mounted. In one embodiment, a single magnet is mounted to a free end of one armature portion, and a nonmagnetic mass of the same moment and weight is mounted at the free end of the other armature to compensate for gravitational forces. Strain gages are mounted adjacent the magnet and the nonmagnetic mass on the pair of armatures. The strain gages are connected in a circuit to generate an output caused by a Lorentz force. The circuit includes provision for static gravity compensation, and in one embodiment l/r compensation.

Apparatus and method for sensing DC current in a conductor

A test system for comparatively analyzing a complex signal indicative of the operational status of an electronic device to be tested includes means (36) for sampling a signal whose characteristics are indicative of the unknown operational status of the electronic device to produce a comparison data base. The comparison data base is processed by a microcomputer (20) to produce comparison transform coefficients. These transform coefficients are compared with a set of reference transform coefficients, representative of a desired operational status of the device, to determine the actual operational status of the device. The sampling means is electrically connected to a conductive element (24) capacitively coupled to the device and permanently mounted in a fixed spatial relationship with the device.

Robert A. Boenning

Papers

Hydrocarbon vapor sensor and system

Multi-channel test system using optical waveguide modulators

Assembly for detecting and locating cable pinching

Apparatus and method for sensing DC current in a conductor

Test system for electronic devices