A device for detecting the presence or concentration of an analyte, a method of making the device, and a method of detecting the presence or concentration of an analyte. The invention features one or more supports, such as beads, which carry a thin film of polymer substrate. The polymer substrate has a sensing reagent and a porous matrix. The sensing reagent alters the optical properties of the polymer substrate in the presence of analyte.
An optical sensor apparatus for detecting a vapor of an organic solvent is characterized by a simple structure which allows easy manufacture, high reliability, low cost, compactness in size, and portability. The optical sensor apparatus has a light source unit which emits light for irradiating a polymer thin film formed on a flat reflecting substrate of a sensing element. Light reflected by the sensing element is detected by a light detecting unit. The light source unit, the sensing element, and the light detecting unit are integrally supported by a housing. The polymer thin film which comes into contact with a vapor of an organic solvent causes a change in the thickness and a reflective index thereof. This change is utilized to detect the existence and/or concentration of a vapor of an organic solvent.
A test kit for determining the "volatile ammonia content" of biological samples comprising any wet or dry compost, manure, plasma or soil sample. The kit includes a transparent container for holding the sample, and a reactant chemistry gel system, located within the container in the space not occupied by the sample. The reactant mass includes an acidic pH reactant material, and a color change indicator material, responsive to pH changes in the reactant material. Ammonia vapors diffuse into the reactant material, reacting chemically with the acidic pH reactant material so as to produce a color change. The nature of the color change is an indication of the quantity of NH.sub.3 in the test-jar atmosphere, which in combination with the known pH of the sample, indicates the total ammonium in the biological sample.
An apparatus and method for detecting, determining and/or quantifying cable flexing for use in optical instruments or in other instruments such as strain gauges, seismometers, and other instruments in which it is desired to detect, determine and/or quantify the degree of flex of a cable or implement that includes, or may be adapted to include, such a cable. A fiber optic, light conduit or similar cable is provided, which may provide light to, and receive light from, an object or material that is being optically characterized. Light may pass from a light source to an object or material, and be returned from the object or material to a spectrometer or set of sensors for determining the optical characteristics of the object or material. A light path is provided through the cable from the object or an end point of the cable to a spectrometer or sensors to return light in order to detect, determine and/or quantify the degree of flex in the cable or changes in the flex of the cable.
A fiber optic moisture sensor is described that can detect the presence or concentration of an analyte in an environment; additionally, a method for making the sensor is described. The invention consists of three primary components: a sensor head, an optical link, and a sensor readout. The sensor head contains the sensing medium, which is comprised of a superabsorbing polymer that hosts a hydrochromic material. The superabsorbing polymer attracts moisture from the environment it is sensing until an equilibrium concentration of water in the environment is obtained effectively magnifying the ability of the hydrochromic material to sense very small concentrations of moisture. An optical link allows light to travel to and from the sensor head. The sensor readout has the necessary electronics to calibrate the optical signal from the sensor head, and the ability to determine and communicate the moisture concentration in the environment being sensed to the user or process control system.
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.
