Homeland Security Brochure  

Chelsea Technologies Group (CTG) is working with UK and US Government Departments and Agencies on developing novel sensor systems for environmental monitoring and protection. The systems are specifically designed to measure a wide range of physical, chemical, biological and optical properties. These enable the natural biological and physical background levels including rivers, reservoirs and abstraction points to be characterised.  

Water Contamination Monitoring 

Understanding the Environment
Water abstraction points are vulnerable to spills from farms or factories, and deliberate contamination through terrorism. Early warning monitoring systems are required to alert operators to these contaminants and to changes in key water quality parameters. A timely response is necessary to prevent contamination and disruption of the public water supply. A long-term baseline of water quality data is required to reduce the occurrence of false alarms and understand typical parameter ranges. CTG is developing systems to observe the natural trends in water quality parameters and rapidly detect anomalies. When a value is outside expected ranges warning signals can be transmitted, increased sampling and testing can be conducted, and the system operation adjusted appropriately.

Novel Systems for Rapid Contaminant Detection  
CTG is conducting a development programme to assess the suitability of the Fast Repetition Rate Fluorescence (FRRF) technology for detecting the effects of hostile contaminants. It is a prime candidate for the real-time monitoring of potable water reservoirs. Studies show that  the ability of water borne algae to photosynthesize, and hence fluoresce, is significantly affected by toxic chemicals. Initial chemicals investigated include methylparathion (an insecticide that is structurally and functionally similar to the nerve gas sarin), potassium cyanide (which can result in nervous system and respiratory failure), diuron and paraquat.

The fluorescence signal from algae in chemically polluted water is impaired compared to signals from algae in clean water. In a monitoring situation algorithms determine the rate of change of fluorescence signal that are independent of algae concentration and changes in ambient light levels. The FRRF measures a time dependent fluorescence signal that arises solely from chlorophyll that is active in photosynthesis - a parameter that can be related directly to the physiology of the algae. The FRRF is therefore capable of discriminating between chlorophyll that is free in the water column, present in dead algae and present in physiologically active organisms.

The response time for the FRRF to detect a deliberate contamination event is a matter of seconds. When combined with historic time series, and other water quality parameters the likelihood of a false alarm is minimised and the threat promptly reported and assessed. This makes it ideally suited for deployments at critical points in water distribution systems to detect contamination of water pre- and post-treatment.
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On-Site Rapid Diagnostics Screening
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Background
Microarrays are becoming an increasingly significant format formulti-analyte testing. The technique has found many applications in gene expression studies and is now being adapted for protein applications including immunodiagnostics.

In a typical configuration, an array of immunoreagent ‘spots’, typically 300µm in diameter, is immobilised on a microscope slide. The assay is performed by introducing a fixed volume of sample to the slide followed by a fluorescently labelled conjugate reagent to reveal the quantity of the target analyte bound to its complimentary immobilised reagent. One of the attractions of the format is that the large number of spots deposited enables internal controls to be run in parallel with the test panel. Thus, any sample factors affecting the fluorescence signal will influence both the test and control spots equally. Further, false positives and/or negative test results can be avoided by providing replicate spots within the array.
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Typical microarray image using
conventional laser scanner

Limitations of Current Technology  
The widespread commercial exploitation of the technique for routine diagnostics applications has been hampered by the cost of the equipment required to read the fluorescent signals from the arrays. This has arisen because the main driver for the development of the format has been DNA analysis, which typically requires the use of high-density arrays, comprising 10,000 spots or more. This has necessitated the use of sophisticated and thus expensive optical techniques capable of resolving the smaller spots used in these arrays.

New Approach Over the past few years CTG has been working with Microtest Matrices Ltd, a commercial spin out from the Department of Biology at Imperial College London, one of the world leaders in the immunoassay applications of protein arrays, to develop a cost effective detection technique for this important new format. Commercial systems currently generate high-resolution images of the microarray, as illustrated opposite. Sophisticated image analysis software is then required to identify the spot positions and integrate the signal from the pixels making up each spot image. CTG has developed an optical system that fully illuminates a single spot in the array and collects its fluorescence emission to produce an integrated signal value from the spot. This significantly reduces the amount of data generated and the processing power required for analysis. Feasibility studies have demonstrated that it is possible to achieve better performance with this approach than is currently possible using a commercial scanning system and at a fraction of the cost.
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Portable Microarray System for CBRN Countermeasure Applications  
Following on from the work described above, CTG has lead a consortium developing a flexible, robust and portable microarray platform for the detection of micro-organisms.

The platform is designed to be rapidly deployed in the event of unexplained clusters of acute febrile illness or fatality, to screen for the presence of a comprehensive panel of micro-organisms that might be associated with a deliberate terrorist attack, allowing these to be ruled out as a potential threat early in any investigation. The microarray format is readily adapted to other applications, including the detection of potentially harmful chemicals in water supplies. CTG is keen to meet with organizations who may be interested in collaborating on commercialization of the platform.

>Download latest news:  'Chelsea aids fight for homeland security with launch of On-Site Rapid Diagnostic Screening System'

Operational Monitoring Systems
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Recent terrorist attacks have lead to an increased emphasis on Homeland Security and the protection of key infrastructure. Unintentional pollution events have already resulted in increased monitoring and the establishment of many of the measures necessary to safeguard our water supply. An early-warning monitoring network can help to ensure abstraction point and water storage protection. The sensors must perform reliably when unattended for extended periods of time, typically many months. Any contamination events must be detected promptly and information passed efficiently to the monitoring station that maybe many miles away. Incorrect reporting of events, and false positives, are unacceptable.

CTG is addressing the new challenges of the Homeland Security threat with our proven capability in sensors and system design for operations in hostile environments. As the design authority for the UK Sonar 2081 and Sonar 2115 oceanographic systems, we understand the demands of operational systems and provide sensors with significantly extended calibration intervals, built in test circuitry and redundancy. Our sensors operate in a range of environments from clear waters with high ambient daylight to extremely turbid conditions. CTG has participated in several European programmes addressing the problem of bio fouling on long-term systems.

CTG is addressing the new challenges of the Homeland Security threat with our proven capability in sensors and system design for operations in hostile environments.

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