This PDF file contains the front matter associated with SPIE Proceedings Volume 7116, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

A novel optical sensor system for rapid, sensitive and robust biological detection is presented. Sensor elements based on integrated optical circuits confine all optical signals into a planar format, resulting in a small, low-cost and mechanically stable refractive index sensor, without any external bulk optics. Consequently, the sensor elements are able to operate in real-world environments, resilient to vibration and temperature changes, whilst maintaining refractive index resolution of 10-6. Oxide surfaces on the sensor are ideal for protein attachment and have a long lifetime in buffer solutions (>100hrs). Real-time, label-free detection of biological agents has been demonstrated using antibodies attached to the sensor surface. The sensor design results in a large penetration depth of the sensing light, up to 1μm into the sample liquid, conferring the ability to detect various classes of biological targets, spanning toxins, viruses and bacteria. Each sensing element utilizes parallel multiple wavelength data to provide additional information at the point of measurement, resulting in on-chip temperature and strain referencing, focused towards increased accuracy and reduction of false alarms. The large size range of biological detection, coupled with the long lifetime of the sensors makes the system ideally suited to applications ranging from medical diagnostics to confirmatory detectors for homeland security

Recently, improvements built upon the core Luminex analyzer technologies have resulted in the development of BeadPix; a low-cost, compact, rugged, diagnostic and environmental testing xMAP analyzer. This instrument moves away from a flow cytometry-based system to an instrument that employs Light Emitting Diodes (LEDs) and a CCD imager, coupled with an improved magnetic microsphere-based array (MagPlex(tm)).

This paper describes a new concept related to the micromechanical sensors for detecting the presence and concentration of chemical substances and/or biological organisms. We believe that this concept allow for a low cost and ease of fabrication of a large bi-dimensional array of sensors with an enhanced signal-to-noise ratio. A bi-dimensional array of micro-cantilever coated with different types of sensing layer enables to identify a characteristic chemical composition of the gas in real-time mode. The selective molecular absorption by cantilever sensing layer will produce cantilever bending proportional to the concentration of molecules. To increase the gas sensor sensitivity, the SPR phenomenon is used for cantilever deflection monitoring.

Laser Induced Fluorescence (LIF) could permit fast early warning systems either for point or stand-off detection if a reliable classification of warfare biological agents versus biological or non-biological fluorescing background can be achieved. In order to improve LIF discrimination capability, a new system is described in which the fluorescence pattern is enriched by the use of multiple wavelength delayed excitation while usual spectral fluorescence analysis is extended to time domain to use both aspects as criteria for classification. General considerations and guidelines for the system design are given as well as results showing good discrimination between background and simulants.

Ultra Violet (UV) induced fluorescence remains a core technique for the real time detection of biological aerosols. With this approach, the detection of an aerosolized biological event is based on the fluorescent and scattering signals observed from biological particles when exposed to one or more UV sources. In 2004, the Edgewood Chemical Biological Center (ECBC) initiated an effort to develop a low cost, small, lightweight, low power biological agent detector, identified as the TAC-BIO, based on this principle. Unlike previous laser based detectors, this program has capitalized on Semiconductor UV Optical Sources (SUVOS) being developed by the Defense Advanced Research Projects Agency (DARPA). Compared to the existing UV lasers, these SUVOS devices and their commercial counter-parts offered a means of achieving small, low cost, low power UV excitation sources. A general design philosophy of incorporating these devices with other low cost components has allowed ECBC to develop a detector that provides a credible degree of performance while maintaining the target size weight and power attributes. This paper presents an overview of the TAC-BIO and some of the findings to date.

A dual wavelength UV-LIF fluorescence system that uses 266 nm and 355 nm laser pulses to sequentially excite single aerosol particles has been shown to provide significant discrimination between biological and ambient as well as differentiation among classes of biological particles. This particle classification data can then be used to trigger an electrostatic capture mechanism to deposit individual potential bio-threats particles onto a stainless steel substrate and particles that are not classified as targets are discharged with the exiting airflow. Timing and velocity information for each on-the-fly particle are critical for setting an appropriate delay to capture the particles of interest. A novel CW laser beam technique has been developed to measure the velocity of each particle and initiate a timing sequence. The electrostatic capture mechanism then electrically charges identified particles and produces a time-delayed electric field to drive them into the stainless steel substrate. The resulting collected sample is highly enriched with target, or potential threat, particles in comparison to their percentage in the ambient air. This presentation will describe the unique optical interrogation and diagnostic techniques that have been developed to make this achievement possible, as well as provide the latest system performance results.

The research project FABIOLA (Fluorescence Applied to BIOLogical Agents detection), coordinated by EDA (European Defense Agency), has two main goals: to demonstrate the feasibility of detection of BW agents using LIF (Laser Induced Fluorescence) technique, and develop BW early warning point detection lab-demonstrator based on LIF. The Optical Detection System collects the fluorescence radiation emitted by the aerosol particle under test (hit by a sequence of two UV laser pulses with 50ns delay), splits it into four wavebands covering the 350-600nm range, and acquires the time decay shape by means of 4 ultra-fast MCP-PMTs that are read by a fast electronics. A fifth PMT is devoted to the acquisition of the elastically scattered signal at the same laser excitation wavelength (293 and 337nm) for data normalization. The Optical Detection System is based on waveband separation by a train of dichroic beamsplitters; high-pass filtering is used for rejection of the scattered excitation beam. A lens system provides parallel beam on dichroics and uniform illumination of MCP-PMTs. Main design drivers of ODS are the four selected fluorescence bands, the required fast response for acquiring decay time of ns-order, and the capability to operate with two excitation pulses (at 293 and 337nm) which shall be effectively rejected by fluorescence channels.

Sensors that are able to provide reagent-free, continuous monitoring for potential bio-aerosol hazards are required in many environments. In general, increasing the number of optical and spectroscopic properties of individual airborne particles that can be measured increases the level of detection confidence and reduces the risk of false-positive detection. This paper describes the development of relatively low-cost multi-parameter prototype sensors that can monitor and classify the ambient aerosol by simultaneously recording both a 2x2 fluorescence excitation-emission matrix and multi-angle spatial elastic scattering data from individual airborne particles. The former can indicate the possible presence of specific biological fluorophores in the particle whilst the latter provides an assessment of particle size and shape.

We report the development of a Single-Particle Fluorescence Spectrometer (SPFS) system capable of measuring two UV-laser excited fluorescence spectra from a single particle on-the-fly. The two dispersed fluorescence spectra are obtained from excitation by two lasers at different wavelengths (263 nm and 351 nm). The SPFS samples single particles with sizes primarily in the 1-10 &mgr;m range. The fluorescence spectra are recorded from 280 nm to 600 nm (in 20 channels) for 263 nm excitation and from 370 nm to 700 nm (in 22 channels) for 351 nm excitation. The elastic scattering (channel 4 and 9) is also recorded for sizing each particle. A time stamp for single particles is marked with a variable time interval resolution from 10 ms to 10 minutes. The SPFS employs a virtual-impactor concentrator to concentrate respirable-sized particles with a resulting (size-dependent) effective flow rate of around 100 liters/min. The SPFS can measure single-particle spectra at a maximum rate of 90,000/sec, although the highest rates we have experienced for the ambient are only several hundred/sec. When the SPFS is combined with an aerodynamic deflector (puffer) to sort particles according to their fluorescence spectral characteristics, the SPFS/puffer system can selectively deflect and collect an enriched sample of targeted particles (at rates limited by the puffer) of 1200 particles/sec, for further examination. In laboratory tests, aerosol particles with similar UV-LIF spectra (e.g. B. subtilis and E.coli) are puffed into the reservoir of a micro-fluidic cell, where fluorescent-labeled antibodies bind to them and were classified by their labeled fluorescence. Measurements of the background ambient aerosol with the SPFS system made at sites with different regional climate (Connecticut, Maryland, and New Mexico) were clustered (unstructured hierarchical analysis) into 8-10 groups, with over 90% of all the fluorescent particles contained within these clusters (threshold dot product=0.9). However, the percentage of aerosols in each profile differed by sampling location. The unique features and performance of the SPFS/puffer system compared to other fluorescence-based bio-aerosol sensors will be discussed, with emphasis on reduction of false alarm rates.

We describe the continuing development of a laser-based, light scattering detector system capable of detecting and analysing liquid-borne nanoparticles. Using a finely focussed and specially configured laser beam to illuminate a suspension of nanoparticles in a small (250ul) sample and videoing the Brownian motion of each and every particle in the detection zone should allow individual but simultaneous detection and measurement of particle size, scattered light intensity, electrophoretic mobility and, where applicable, shape asymmetry. This real-time, multi-parameter analysis capability offers the prospect of reagentlessly differentiating between different particle types within a complex sample of potentially high and variable background. Employing relatively low powered (50-100mW) laser diode modules and low resolution CCD arrays, each component could be run off battery power, allowing distributed/remote or personal deployment. Voltages needed for electrophoresis measurement s would be similarly low (e.g. 20V, low current) and 30second videos (exported at mobile/cell phone download speeds) analysed remotely. The potential of such low-cost technology as a field-deployable grid of remote, battery powered and reagentless, multi-parameter sensors for use as trigger devices is discussed.

To enhance discrimination of UV-laser-induced-fluorescence based bio-aerosol-detection-system, a UV-laser is described that allows multiple wavelength excitation of bio-aerosols and both fluorescence spectral and time-decay analysis. The latter requiring sub-ns pulse duration, a two-stage-amplifier boosts a 20-µJ-1064-nm-500-ps-actively-Q-Switch microchip-oscillator output energy up to 2.5 mJ. After frequency doubling and beam splitting, 20-µJ-293-and-337-nm pulses are generated by two different periodically-poled-KTP (parametric generation) and BBO (frequency doubling) crystal arrangements. In order to get distinct fluorescence signals for each wavelength, the beams are then time-delayed with two optical fibers of different lengths and launched into a chamber for bio-aerosol excitation connected to a fast detection system.

The quick increase of terrorism and asymmetric war is leading towards new needs involving defense and security. Nowadays we have to fight several kind of threats and use of chemical weapons against civil or military objectives is one of the most dangerous. For this reason it is necessary to find equipment, know-how and information that are useful in order to detect and identify dangerous molecules as quickly and far away as possible, so to minimize damage. Lidar/Dial are some of the most powerful optical technologies. Dial technology use two different wavelengths, in order to measure concentration profile of an investigated molecule. For this reason it is needed a "fingerprint" database which consists of an exhaustive collection of absorption coefficients data so to identify each molecule avoiding confusion with interfering ones. Nowadays there is not such a collection of data in scientific and technical literature. We used an FT-IR spectrometer and a CO₂ laser source for absorption spectroscopy measurements using cells filled with the investigated molecules. The CO₂ source is the transmitter of our DIAL facility. In this way we can make a proper "fingerprint" database necessary to identify dangerous molecules. The CO₂ laser has been chosen because it is eye safe and, mainly, because it covers a spectral band where there is good absorption for this kind of molecules. In this paper IR spectra of mustard will be presented and compared to other substances which may interfere producing a false alarm. Methodology, experimental setup and first results are described.

The detection and identification of hazardous chemical agents are important problems in the fields of security and defense. Although the diverse environmental conditions and varying concentrations of the chemical agents make the problem challenging, the identification system should be able to give early warnings, identify the gas reliably, and operate with low false alarm rate. We have researched detection and identification of chemical agents with a swept-field aspiration condenser type ion mobility spectrometry prototype. This paper introduces an identification system, which consists of a cumulative sum algorithm (CUSUM) -based change detector and a neural network classifier. As a novelty, the use of CUSUM algorithm allows the gas identification task to be accomplished using carefully selected measurements. For the identification of hazardous agents we, as a further novelty, utilize the principal component analysis to transform the swept-field ion mobility spectra into a more compact and appropriate form. Neural networks have been found to be a reliable method for spectra categorization in the context of swept-field technology. However, the proposed spectra reduction raises the accuracy of the neural network classifier and decreases the number of neurons. Finally, we present comparison to the earlier neural network solution and demonstrate that the percentage of correctly classified sweeps can be considerably raised by using the CUSUM-based change detector.

The ability to remotely locate and identify liquid droplets coated upon surfaces is desirable in a variety of civilian and military applications. The fusion of imaging and optical spectroscopy is a promising route to produce technologies that fulfill this requirement. Hence, a novel system based on Raman line imaging is presented. The device utilises a frequency doubled Nd:YAG to produce 532 nm light pulses of energy ca. 400 mJ. This incident light is projected to form a 2 x 500 mm line, whereupon it interacts with a target scene and the resultant Raman shifted light is returned to an auto focus lens. A time-gated, intensified CCD detector is used to collect this light, which is synchronised to the probe laser pulse, thereby significantly suppressing ambient light and fluorescence effects. A library of characteristic spectra that are unique to each chemical species are used to identify the deposited substance. Results of initial experiments to characterise the instrument for remote detection are also reported, including the feasibility of single shot detection.

In this study two issues are addressed, namely laser ionisation of selected nitroaromatic compounds (NAC) and the characterisation of their anions by photodetachment (PD) spectroscopy. Laser ionisation of the NAC at λ = 226.75 nm is investigated by ion mobility (IM) spectrometry at atmospheric pressure. The main product after laser ionisation is the reactive NO+ ion formed in a sequence of photofragmentation and multiphoton ionisation processes. NO+ is trapped by specific ion molecule reactions (IMR). Alternatively, NO, added as laser dopant, can directly be ionised. The formed NO+ reacts with the NAC under complex formation. This allows fragmentless NAC detection. The combination of IM spectrometry and PD spectroscopy provides real-time characterisation of the anions in the IM spectrum. This is useful to differentiate between NAC and interfering substances and, thus, to reduce false-positive detections of NAC. The electrons detached by the PD laser at λ = 532 nm are detected in the same spectrum as the anions. The potential of PD-IM spectrometry in terms of cross section determination, analytical improvements, tomographic mapping, spatial hole burning etc., is outlined.