An optical sensing element for use in the detection of hydrogen peroxide includes a sensing compound provided as a coating on a substrate. The sensing compound, on exposure to hydrogen peroxide, forms a luminescent reporter compound when excited with stimulating radiation at a predetermined wavelength that the sensing compound does not absorb.

Methods and apparatus for determining levels of gaseous elements and optionally utilizing the determined levels to calibrate one or more sensors of an air purifier. For example, in some implementations a first image is captured of a colorimetric sensor device at the start of a sensing period and a second image is captured of the colorimetric sensor device at the end of the sensing period. The colorimetric sensor device includes at least one colorimetric sensor configured to change colors in response to reaction with a gaseous pollutant. Values may be determined based on the colors of the colorimetric sensor in the first and second images and the values may be utilized to determine a pollution value indicative of the amount of the gaseous pollutant to which the colorimetric sensor was exposed during the sensing period.

A method for the detection of adulterated gasoline in a sample is disclosed. The method includes contacting a sample with an immobilized molecular probe, the immobilized molecular probe having a photoluminescence which is environmentally sensitive; collecting the photoluminescence from the immobilized molecular probe; and determining whether the photoluminescence is indicative of adulterated gasoline. A test strip for the detection of adulterated gasoline in a sample is also disclosed, including an immobilized molecular probe embedded in a substrate and/or immobilized to the substrate, the immobilized molecular probe having photoluminescence which is environmentally sensitive to adulterated gasoline. The method and test strips are designed to be robust, portable, and within the capabilities of untrained personnel.

The invention generally relates to methods, reagents, and substrates for detecting target analytes.

Hydrogen gas sensors with low cost, fast response time, large detection range, high sensitivity, and excellent limit of detection are described. The devices include a composite formed on a nano-scale that both absorbs hydrogen and exhibits magneto-optical effects. Sensor readout is based on magneto-optical effects, which also may be enhanced through plasmonic coupling. The hydrogen sensors are fast and sensitive, as well as resistant to surface poisoning from common contaminants, such as carbon monoxide.

An optically transparent matrix including a molecule containing a hydroxyazobenzene group or its derivative embedded in the matrix. An optical system including the optically transparent matrix, an isomerizing light source, and one or more light detector(s) for measuring absorbance changes from the optically transparent matrix. A method for measuring the quantity of hydrogen bonding gaseous molecules.

The problem of detecting whether a urine sample is true human urine or a counterfeit urine product is solved by the use of reagent systems that detect two markers normally present in human urine. The markers acid phosphatase and alkaline phosphatase catalyze the substrates thymolphthalein monophosphate and p-nitrophenol phosphate, respectively. These substrates are formulated as spot tests on a dip stick or as reagents for use in automated chemical analyzers. The presence of the markers can be qualitatively detected by color-changes in the sample, formed by the pH-specific chromogens that result from catalysis of the substrates with the markers. The control reagent can further indicate whether a counterfeit urine product contains one or both of the chromogens.

Methods and apparatuses for determining levels of gaseous elements and optionally utilizing the determined levels to calibrate one or more sensors of an air purifier. For example, in some implementations a first image is captured of a colorimetric sensor device at the start of a sensing period and a second image is captured of the colorimetric sensor device at the end of the sensing period. The colorimetric sensor device includes at least one colorimetric sensor configured to change colors in response to reaction with a gaseous pollutant. Values may be determined based on the colors of the colorimetric sensor in the first and second images and the values may be utilized to determine a pollution value indicative of the amount of the gaseous pollutant to which the colorimetric sensor was exposed during the sensing period.

A system for detecting target molecules includes a sample well defining a sensing region and two electrode regions, a sensor positioned in the sensing region and sensitized to the target molecules, an electrode positioned in each electrode region and configured to expose the sensor to a frequency-modulated electric field, and a detector configured to detect both an amplitude of oscillation of the sensor at a frequency of the modulated electric field and a direction of a displacement of the sensor. The sensing region defines a channel between the electrodes, and a ratio of a current density at a center of the sensing region to a current density at one of the electrodes is at least 2. The system allows detection of target molecules in a normal ionic strength buffer (e.g., having an ionic strength in a range of about 10 mM to about 1 M).

Multi-stage sample-recovery systems, including automated 2-stage and 3-stage sample-recovery systems, are provided. Such systems enable the rapid screening and recovery of samples, including viable cell-based samples, from high-throughput screening systems, including systems utilizing large-scale arrays of microcapillaries. In specific screening systems, each microcapillary comprises a solution containing a variant protein, an immobilized target molecule, and a reporter element. Immobilized target molecules may include any molecule of interest, including proteins, nucleic acids, carbohydrates, and other biomolecules. The association of a variant protein with a molecular target is assessed by measuring a signal from the reporter element. The contents of microcapillaries identified in the assays as containing variant proteins of interest can be identified and recovered using the multi-stage systems disclosed herein.