8-Channel Bioassay System Operational Details
Air Sampler Features
The air sampler is a highly effective multi-stage wetted-wall cyclone that continuously processes air at a 325 LPM rate, extracting particulates and transferring them to a liquid phase of 4 to 5 cc volume (see Figure 1). Distilled water is typically the liquid of choice; no additives or surfactants are required for maximum efficiency. This liquid portion may then be periodically transferred in part or in whole to the biodetector, using a built-in peristaltic pump. A dropper bottle filling station is also integrated into the BioHawk so that a portion or all of the sample may be dispensed into the dropper bottle for archiving and/or application of an alternative analysis method. For example, the dropper bottle feature allows the BioHawk to be used as a sample collection and preparation system for lateral flow tickets. Unique and patented features of the air sampler include its abilities to operate unattended for long periods of time and to amplify trace analyte concentrations by maintaining a user-selected sample fluid volume in the device, independent of collection time, air temperature or relative humidity.
This is accomplished by monitoring liquid inventory with a proprietary sensor attached to the cyclone body. When the sample water inventory falls below the set point, the sensor initiates clean water transfer into the cyclone body from an onboard 1 liter water supply. 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 cubic centimeter.
The instrument's biodetector section consists of a disposable 8-channel fluorometric assay coupon (see Figure 2) suitable for the high-sensitivity detection of biological agents, toxins, explosives, and chemical contaminants. All target-specific reagents needed to perform an assay are contained within the coupon. The only fluid not carried in the coupon is a saline buffer used to wash the system between assays. It is stored within a refillable reservoir in the instrument and a waste water reservoir is also provided. This ensures that no fluids are discharged from the instrument during either air sampling or the bioassay step.
Upon coupon insertion into the instrument, an optical bar code on the coupon is automatically interrogated for assay recipe information. Highly reliable computer-controlled peristaltic and syringe pumps are used to move reagents, sample fluids and wash buffer within the coupon, as directed by the assay recipe. Automation of the assay process in this way ensures repeatable behavior from test to test.
Targeted agents are detected by monitoring fluorescently-tagged chemical reporter reactions taking place on optical waveguide surfaces within the coupon (see Figure 3). These reactions typically use antibodies to bind targeted pathogens to the waveguide surfaces, and fluorophore-tagged secondary antibodies to create a fluorescent signal when the waveguides are irradiated with 635 nm solid state laser light. See the RAPTOR Sandwich Assays chart for additional information on waveguide-based biosensing and analytes that can be detected with this type of approach.
Assay data is automatically stored in the system's non-volatile EEPROM with a date and time stamp, and can be downloaded to a remote computer using an RS-232 or wireless link. The BioHawk has the capacity to save up to 6,000 data sets.
Auxiliary Windows-based software allows the user to graphically monitor data recovery while an assay is running. It also provides sophisticated users with the ability to customize the various steps involved in running an assay.
The BioHawk Program runs in a single main window entitled “BioHawk” which contains a menu and Toolbar at the top, and a status panel at the bottom. The Main window (see Figure 6) can be minimized or reduced in size without affecting operation or data acquisition. Important messages requiring manual input will continue to be displayed even when the program is minimized.
(This product is covered by one or more of the following patents: U.S. Patents No. 6,136,611; 5,430,813; 6,082,185; 6,532,835; 5,061,857; and Japanese Patents No. 3,429,282 and 3,754,440.)