Looking Small for Big Solutions
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THE JOINT EXECUTIVE PROGRAM OFFICE FOR CHEMICAL AND BIOLOGICAL DEFENSE HAS TWO PROGRAMS THAT IT HOPES SMALL BUSINESS CAN PROVIDE SOLUTIONS.
Large lead systems integrators and prime contractors control and have distinct advantages in doing business with the DoD. However, the DoD has also long recognized that innovation and rapid response to requirements are sometimes met by agile small businesses.
The Joint Executive Program Office for Chemical and Biological Defense (JPEO CBD) currently has two programs that are open to small business solutions.
ULTRA-SENSITIVE TOXIC CHEMICAL DETECTION
The joint services have the need for a miniature, highly sensitive and yet highly specific (low false alarm) sensor for detection of toxic industrial chemicals. Infrared absorption spectroscopy has proven to be a very useful tool in the detection and precise identification of airborne chemicals. Pattern recognition is used to compare the infrared spectrum of library molecules against the infrared spectra of airborne contaminants.
Infrared spectroscopy has been used to detect chemicals at extremely low concentrations with detection limits comparable to standard methods such as ion mobility spectrometry and surface acoustic wave spectroscopy.
Infrared spectroscopy also holds the promise of very low false alarm rates due to the spectral pattern matching over a large number of spectral bins. Infrared spectrometers can also provide quantitative information regarding cloud concentrations. Infrared spectrometers have rapid response and clear-down times, which provide utility in cloud tracking or dynamic monitoring experiments.
However, current infrared spectrometers are large and expensive or small and relatively insensitive. The size, weight, and power requirements of current infrared spectrometers have limited their utility in field environments.
In recent years there has been much activity in developing tunable laser based infrared absorption spectrometers which are capable of extreme sensitivity and spectral resolution. They have enabled IR absorption measurements over relatively long paths (in multipass cells) and exhibit spectral resolution easily capable of discriminating isotopic species. An appropriately designed system could be configured for high sensitivity in detecting chemical warfare agents and toxic industrial chemicals (TICs) in the environment.
Further application of the technology to bio-aerosol detection may also be possible. There may even be potential for short-range standoff operation. The problems of adequate tuning range, wavelength monitoring and stability while managed in larger systems, represent a challenge in miniaturized devices which could be amenable to MEMS (micro electro mechanical sensor) solution. A miniature tunable laser IR absorption spectrometer would be extremely small and consume much less energy than the extant units. Miniature lasers with MEMS monitoring should allow for compact devices more amenable to substantial cost reduction.
The goal of this JPEO CBD program is to develop an extremely sensitive miniature sensor system with very low false alarm rates that is approximately 1,800 cm3 or less in size, including power supply. The sensor should run on standard batteries without an outside power source.
Besides an established military need, first responders such as civil support teams and local fire departments have a critical need for a relatively inexpensive but versatile and rugged sensor that can be transported to the field to test for possible contamination of various chemicals to include CW agents. The potential for shortrange standoff capability enhances this utility.
During Phase I development of the program it is hoped to design a tunable laser based infrared chemical sensor. The initial brassboard design would include selection of laser(s), analysis to indicate adequate spectral coverage for the defined military threats, selected TICs and military interferents. It is also expected that modeling of anticipated sensitivity and the limiting source of noise would be addressed.
If the program moves to Phase II, it would fabricate the laser diode based chemical sensor. While the brassboard developed in Phase I need not meet all size and weight constraints, a definitive and practical analysis indicating the path from brassboard to prototype would have to be defined with weight, power and size limit goals by major subsystem. The device would have to measure the sensitivity to selected simulants and establish the limiting noise source and using a recognition algorithm of choice, determine the variance possible in wavelength and amplitude versus false alarm rate.
Phase III would see a prototype undergo testing and analysis against a wide range of chemicals in order to define operational parameters and determine if the device would meet operational requirements as defined by the Joint Chemical and Biological Defense Program. There are numerous environmental applications for a small ultrasensitive, chemical detector/identifier.
DETECTION IN EXTREME ENVIRONMENTAL CONDITIONS
Colorimetric technology has been used and accepted for detecting TICs and chemical warfare agents (CWAs) in vapor or liquid form. Some advantages of colorimetric technology are low cost, easy to use, and requires no external power source (e.g. battery). A major drawback of most current colorimetric technologies is the inability to withstand ‘real-world’ ambient operating conditions (including heat, humidity, water immersion and long-term shelf life in adverse environments), and the inability to quickly detect TICs and CWAs at relevant low concentrations.
To meet this requirement, the JPEO CBD prefers an innovative technology to develop passive (i.e. no active sampling required) colorimetric sensors which meet the following criteria: physical requirements are low-cost (<$3 per sensor), light-weight, require no external power source, physically rugged.
Requirements for the user include minimal operator training and be in a configuration easily deployed and used by the warfighter or personnel equipped in personal protective equipment.
Operational requirements include compliant functioning in arctic, tropic, and desert conditions for a minimum of 24 hours, have an in-package shelf life of at least one-year at ambient temperature, is directly immersible in salt water and fresh water for at least one hour without impacting performance following aqueous exposure, can detect TICs/CWAs in vapor phase at PEL levels within 15 minutes or less, and detect TICs/CWAs in vapor form at one-half IDLH levels in five minutes or less.
The first phase of the project hopes to develop and test multiple chemistries for detecting selected high-risk TICs and CWAs, and conduct testing with an array of TICs and CWA simulants in vapor form. At this point, proposed devices must demonstrate: (i) the successful development of colorimetric chemical sensors to meet the performance requirements listed in the description above for detecting at least five high-risk TICs, and (ii) the current ability to generate, in the laboratory, precise concentrations (validated against analytical methods) of vapors for targeted TICs and CWA simulants.
Phase II will build on the results of the first phase and incorporate chemistries into at least three new passive colorimetric sensors—detecting a different TIC or CWA).
The device will also be tested and validated with an array of TICs and CWAs in vapor form. ♦