ASAP II Operational Details

Overview

In operation, the SASS 2300 air sampler (US patent 6,532,835), samples air from targeted areas continuously and transfers particulates in the air to a secondary water phase of about 4 to 5 ml volume: Aerosol sampling is performed using aerodynamically sound methods certified by fluid dynamic software models. Water samples of 1 to 2 cc are periodically transferred from the SASS 2300 to the RAPTOR. The RAPTOR then automatically performs a multi-step bioassay for up to four bio-targets on the liquid sample using a disposable assay coupon. Each of these 4-channel assay coupons may be reused from 20 to 50 times over a 36-hour unattended operating period before replacement of the coupon and related reagents is necessary. This provides extremely competitive per-assay costs and allows operation by minimally trained personnel.

The fixed-installation system includes 5-day reservoirs for wash and sampling fluids and waste water, yet weighs only 80 pounds (36 kg) and consumes an average power of 30 watts. A Windows® software package installed on a remote laptop or desktop PC allows operating personnel to monitor system and assay results in real-time and to introduce random biosamples into the workflow as needed. A large green/amber safety light connected to one of the PC's USB ports immediately communicates system status to nearby workers.

Developmental sandwich format fluoroimmunoassays are offered for ricin and anthrax. Various researchers have also demonstrated good sensitivity in a lab setting for a number of other BW agents including Francisella tularensis, Y. pestis F1 antigen, botulinium toxin, and Straphylococcus enterotoxin B. Many other pathogens and toxins may also be targeted with relative ease: contact us to discuss your needs.

OPERATING PRINCIPLES: ASAP II AIR SAMPLER

A schematic representation of the ASAP II's air sampler is shown in Figure 1. Sampled air travels through four main sections: a cyclonic cup, stripping column, cistern, and water feedback loop. A high-efficiency centrifugal blower at the sampler's exit pulls air through the unit. When operating, incoming air enters at the cyclonic cup perimeter, creating strong vortex action and a rapidly swirling film of water on exposed surfaces. This water film passes across the air inlet region, forming a water curtain through which sampled air first passes.

Concurrently, a centrally located nozzle projecting from the cup base injects additional water. This location is subject to high air shear and fluid discharged from the nozzle into the cup forms a fine spray that is particularly useful for impingement collection of smaller particles and molecular species. The rapidly rotating air then enters a vertical stripping column where additional particulates are captured by centrifugal action: Air-water shear forces in this section create a concurrent upward flowing water film on the interior surface.

This film and the sampled air are discharged into a large diameter cistern section. Entering water is trapped and gravity-fed back into the cyclonic cup via a feedback tube and the aforementioned nozzle, while sampled air discharges through the fan. This 'pumpless' water recirculation loop will cycle a typical 4 to 5 cc fluid inventory through the unit from 6 to 20 times per minute.

Fluid Control Subsystem

Liquid inventory is monitored with a proprietary sensor attached to the water feedback tube. Water inventories may be maintained within a recommended range of about 4 cc to 5 cc with an accuracy of a few tenths of a cc, independent of temperature, relative humidity, or operating time. Samples may be removed at any point independent of ongoing air sampling, using the on-board microcontroller based peristaltic pump. A flow rate of approximately 12 cc/minute at a maximum delivery pressure of about 300 mmHg is provided. Pump power is a modest 180 mW at 12 V DC.

More information on SASS 2300 technology

OPERATING PRINCIPLES: ASAP II BIO-IDENTIFIER

The ASAP II uses bio-identification technology that is based on the company's RAPTOR 4-channel fluorometric assay system (US patents 6,082,185 and 6,136,611). This bio-identifier can be used for high-sensitivity monitoring of biological agents, toxins, explosives, and chemical contaminants. It can automatically perform factory- or user-defined, multi-step, fluid transfer protocols while simultaneously tracking fluorescently-tagged chemical reactions occurring on the surface of each of the system's four disposable optical waveguide sensors (see Figure 2).

Each waveguide may be used to target a different pathogen or toxin, allowing the simultaneous monitoring of up to four different pathogens. The results of these assays are displayed on a four line x 16 character LCD. For the fixed-installation ASAP IIa, executive-level decisions are dictated from a desktop or laptop PC via an RS-232 link using the Windows-based user interface provided.

Each waveguide may be used to target a different pathogen or toxin, allowing the simultaneous monitoring of up to four different pathogens. The results of these assays are displayed on a four line x 16 character LCD. The RAPTOR can also be run from a desktop PC, via an RS-232 link, using Windows-based software that is provided with the system.

USER CONTROLS/DISPLAY

PC-based control software provides user-friendly system status information and local or global network connectivity.

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