A sensing system for explosives is provided. The sensor is based on a layered structure of approximately a monolayer of a fluorophore deposited onto a few nm of a transparent polymer, supported by a substrate. The fluorophores can be xanthene laser dyes, which have high quantum yields, and the polymers can be commodity materials polymethylmethacrylate and polyvinylidene difluoride. The different fluorophore/polymer combinations give different emission responses to analytes, including both signal quenching and enhancement. The pattern of responses can be used to identify the analyte. The common explosives TNT, PETN, RDX, HMX, and TATP as gas phase species can all be uniquely identified at room temperature using only the natural vapor pressure of the explosive to deliver sample to the sensor.

A concentric APCI surface ionization probe, supersonic sampling tube, and method for use of the concentric APCI surface ionization probe and supersonic sampling tube are described. In an embodiment, the concentric APCI surface ionization probe includes an outer tube, an inner capillary, and a voltage source coupled to the outer tube and the inner capillary. The inner capillary is housed within and concentric with the outer tube such that ionized gas (e.g., air) travels out of the outer tube, reacts with a sample, and the resulting analyte ions are sucked into the inner capillary. A supersonic sampling tube can include a tube coupled to a mass spectrometer and/or concentric APCI surface ionization probe, where the tube includes at least one de Laval nozzle.

The present disclosure is directed to methods and systems for detecting a chemical substance. The methods and systems include mixing a sample of a substance of interest with an additive and then producing an adduct using an ionization source. The systems and methods further include performing a spectrometric analysis of the adduct and identifying the sample using comparative spectrometric data.

Provided are methods, devices and systems that utilize free-surface fluidics and SERS for analyte detection with high sensitivity and specificity. The molecules can be airborne agents, including but not limited to explosives, narcotics, hazardous chemicals, or other chemical species. The free-surface fluidic architecture is created using an open microchannel, and exhibits a large surface to volume ratio. The free-surface fluidic interface can filter interferent molecules, while concentrating airborne analyte molecules. The microchannel flow enables controlled aggregation of SERS-active probe particles in the flow, thereby enhancing the detector's sensitivity.

A chemical sensing system includes a substrate material, a detector capable of indicating a presence of a target compound, gas, or vapor, and a heater for rapidly releasing compounds, gases and vapors from the substrate material. The substrate material acts to concentrate the compounds, gases, and vapors from a sample area for improved detection by the detector.

The present invention provides devices and methods for the impregnation of air with the vapor or aerosol of a substance in a ‘controllable manner to enable the testing or training of detection means to evaluate and quantify the presence of the substance in an enclosed volume, and iη• particular to enable production of training aids and quality assurance test items for use in canine-olfaction based security screening.

A system that screens for particularly identified odors, such as those associated with explosive and other bomb-making materials, weapons and illegal drugs, includes an odor delivery unit with one or more fans that force air across the object being screened, such as a person. The airflow from the odor delivery unit passes over and across the object being screened creating an odor stream that passes through a partition that allows the odor stream to flow freely through it and simultaneously obscures a canine positioned on the other side of the partition from view by the person or object being screened.

An apparatus comprises a load resistance connectable in series with the electronic sensor to form a series resistance of the load resistance and the internal impedance of the electronic sensor; an excitation circuit configured to apply a predetermined voltage to a circuit element; and a measurement circuit configured to: initiate applying the predetermined voltage to the series resistance and determining the series resistance; initiate applying the predetermined voltage to the load resistance and determining the load resistance; and calculate the internal impedance of the sensor using the determined series resistance and the load resistance, and provide the calculated internal impedance to a user or process.

A wireless sensor platform design and a single walled carbon nanotube/ionic liquid-based chemidosimeter system can incorporated into a highly sensitive and selective chemical hazard badge that can dosimetrically detect an analyte down to a sub parts-per-million concentration.

An unmanned vehicle operated autonomously or by remotely piloting incorporates an onboard camera which is affixed with clear tape coated with a chemical colorimetric sensor dye sensitive to chemical warfare agents. Chemical warfare agents are detected by visual review or autonomous measurement of sensor color changes while the unmanned vehicle travels through a region suspected of having chemical warfare agents present. In various implementations, the sensor output color changes may be visually monitored by a vehicle operator viewing the camera image from a remote location. In various embodiments, the detection of chemical warfare agents may be confirmed by processing the coated tape with a calibrated opto-electronic reader.