Abstract: An apparatus for detecting chemicals in a fluid includes a preconcentrator tube connected to a bi-directional pump and to a detector. The preconcentrator tube contains a sorbent material in thermal contact with a heating element. The bi-directional pump pumps fluid in a first direction through the sorbent material, thereby causing some of the chemicals to accumulate on one side of the sorbent material. The bi-directional pump is reversed so as to pump fluid in a second opposite direction, thereby causing the accumulated chemicals to be carried to the detector. The sorbent material is heated while the bi-directional pump is reversed. Preferably, the detector is equipped with a separate pump that draws fluid to the detector.

Abstract: A device samples chemicals adsorbed to a surface by applying a pulse of fluid to desorb the particles adhered to the surface. After the pulse of fluid, the region above the surface is enriched with particles dislodged from the surface. Suction is applied in the region above the surface to collect these dislodged particles, which are then transferred to a chemical detector for detection, identification, and quantification. A pulsed air sampler collects particles adhered to a surface and delivers the particles to a chemical sensor. An outlet ejects a fluid, preferably gas, pulse to dislodge particles from the surface and thereby enrich the density of particles above the surface. An inlet collects the dislodged particles for delivery to the chemical sensor.

Abstract: A device for detecting chemical substances includes a plurality of sensors arranged in an array. The sensors are connected to respective oscillator circuits which drive the sensors, and the oscillator circuits are coupled to a power multiplexer which provides the circuits with power according to a timing pattern such that not all of the oscillator circuits are activated at any one time. Preferably, only one oscillator circuit is activated at any given time. This multiplexing arrangement saves power and substantially eliminates cross talk between the oscillator circuits. The oscillator circuits are preferably application specific integrated circuits (ASICs), and the sensors are preferably surface acoustic wave (SAW) devices. In use, the SAW sensors are exposed to a gas, such as air, containing the chemical substance to be detected. Signals from the SAW sensors are analyzed to identify the chemical substance.

Abstract: A device samples chemicals adsorbed to a surface by applying a pulse of fluid to desorb the particles adhered to the surface. After the pulse of fluid, the region above the surface is enriched with particles dislodged from the surface. Suction is applied in the region above the surface to collect these dislodged particles, which are then transferred to a chemical detector for detection, identification, and quantification. A pulsed air sampler collects particles adhered to a surface and delivers the particles to a chemical sensor. An outlet ejects a fluid, preferably gas, pulse to dislodge particles from the surface and thereby enrich the density of particles above the surface. An inlet collects the dislodged particles for delivery to the chemical sensor.

Abstract: A real time nonvolatile residue (NVR) monitor operates to efficiently detect molecular contamination in a given environment. The present NVR monitor utilizes surface acoustic wave (SAW) resonators in a controlled environment which efficiently promotes deposition of NVR on the sensor surface. The SAW resonators preferably operate at a resonant frequency of approximately 200 MHz-2,000 MHz which enables the NVR monitor to detect molecular contamination on the order of 10.sup.-11 g-cm.sup.-2 to 10.sup.-13 g-cm.sup.-2. The NVR monitor utilizes active temperature control of (SAW) resonators to achieve a stable resonant frequency and to thermally separate NVR from a sample fluid contacting the SAW. The temperature control system of the NVR monitor is able to directly heat and cool the SAW resonators utilizing a thermoelectric element to maintain the resonators at a preset temperature in accordance with optimal environmental conditions for separating NVR from the sample fluid.

Abstract: A real time non-volatile residue (NVR) monitor, which utilizes surface acoustic wave (SAW) resonators to detect molecular contamination in a given environment. The SAW resonators operate at a resonant frequency of approximately 200 MHz-2,000 MHz which enables the NVR monitor to detect molecular contamination on the order of 10.sup.-11 g-cm.sup.-2 to 10.sup.-13 g-cm.sup.-2. The NVR monitor utilizes active temperature control of (SAW) resonators to achieve a stable resonant frequency. The temperature control system of the NVR monitor is able to directly heat and cool the SAW resonators utilizing a thermoelectric element to maintain the resonators at a preset temperature independent of the environmental conditions. In order to enable the direct heating and cooling of the SAW resonators, the SAW resonators are operatively mounted to a heat sink.