Industrial processes, which eliminate high concentration of oil in their waste stream, find it extremely difficult to measure and control the water purification process. Most oil separation processes involve chemical separation using highly corrosive caustics, acids, surfactants, and emulsifiers. Included in the output of this chemical treatment process are highly adhesive tar-like globules, emulsified and surface oils, and other emulsified chemicals, in addition to suspended solids. The level of oil/hydrocarbons concentration in the wastewater process may fluctuate from 1 ppm to 10,000 ppm, depending upon the specifications of the industry and level of water quality control. The authors have developed a sensing technology, which provides the accuracy of scatter/absorption sensing in a contactless environment by combining these methodologies with reflective measurement. The sensitivity of the sensor may be modified by changing the fluid level control in the flow cell, allowing for a broad range of accurate measurement from 1 ppm to 10,000 ppm. Because this sensing system has been designed to work in a highly invasive environment, it can be placed close to the process source to allow for accurate real time measurement and control.

We have designed a series of luminescent polymeric chemosensors consisting of an emissive conjugated polymeric backbone functionalized with receptor moieties. These polymers are based on the highly luminescent polyphenylene ethynylene thienyl ethynylene polymer backbone (PPETE) to which Lewis base receptor moieties such as tolylterpyridine and bipyridine have been added as pendant functional groups at the thienyl units. Emission quenching studies on these polymers in the presence of transition metal ions led to the observation of positive deviations from Stern-Volmer behavior. Each pendant polymer deviates from linear Stern-Volmer quenching differently depending on which transition metal ion is present in solution. Further, the relative loading of transition metal ions onto these polymers determines the onset of positive deviation from linear quenching. These two factors can be utilized to generate an array of polymers differentiated in concentration on one axis and pendant- functionality on the other to determine the identity and relative concentration of transition metal analytes in solution. We have demonstrated this approach through UV-Vis absorption, emission spectroscopy, and Stern-Volmer quenching analyses.

Real-time mixture analysis is widely needed in environmental monitoring, kinetics analysis, and industrial process monitoring etc. Conventional methods for mixture analysis such as HPLC, HPLC/MS, or GC/MS, are not good for real-time purposes. Recently, we have demonstrated fluorescence polarization could be used as an additional dimension with which to distinguish fluorescent molecules by the introduction of some specific micelles. In this report, a novel method, the polarized fluorescence spectrometry including polarization information, has been proposed and used for simultaneous determination of fluorescein (FLR) and rhodamine 123 hydrate (R123H) without spectral dispersion. This could also be used for enhanced analytical determination of mixed fluorophores with 2-D fluorescence (excitation-emission matrix). At this time, conventional 2-D fluorescence spectra already provide enough information for principal component regression (PCR) or parallel factor analysis (PARAFAC) to distinguish four fluorophores: FLR, R123H, rhodamine 6G (R6G), and rhodamine B (RB), even FLR and R123H have a very similar 2-D fluorescence spectra.

Two techniques are compared using total luminescence spectroscopy to detect endospore material in preparations equivalent to 3.0 x 10⁵/ml spores. The first method applied intrinsic, steady-state photoluminescence for detection. The second approach using a binding fluorochrome derived from 4-p-dimethylaminostyrylpyridinium (DASP) to signal the presence of spore material. Comparative fluorescence emission signatures (excited at 469 nm) showed greater calibrated signal recovery (4x10⁶ cps) for spore material at longer wavelengths using DASP. The intrinsic fluorescence emission of endospores (excited at 346 nm) occurred at shorter wavelengths and showed a reduced calibrated intensity (1.4 x 10⁵ counts per second (cps). One major advantage of DASP appears to be its longer wavelength excitation (469 nm) that is out of the range of associated biological materials that compete for absorption at shorter UV wavelengths.

The ability to detect viable organisms in air in real time is important in a number of applications. Detecting high levels of airborne organisms in hospitals can prevent post-operative infections and the spread of diseases. Monitoring levels of airborne viable organisms in pharmaceutical facilities can ensure safe production of drugs or vaccines. Monitoring airborne bacterial levels in meat processing plants can help to prevent contamination of food products. Monitoring the level of airborne organisms in bio-containment facilities can ensure that proper procedures are being followed. Finally, detecting viable organisms in real time is a key to defending against biological agent attacks. This presentation describes the development and performance of a detector, based on fluorescence particle counting technology, where an ultraviolet laser is used to count particles by light scattering and elicit fluorescence from specific biomolecules found only in living organisms. The resulting detector can specifically detect airborne particles containing living organisms from among the large majority of other particles normally present in air. Efforts to develop the core sensor technology, focusing on integrating an UV laser with a specially designed particle-counting cell will be highlighted. The hardware/software used to capture the information from the sensor, provide an alarm in the presence of an unusual biological aerosol content will also be described. Finally, results from experiments to test the performance of the detector will be presented.

In recent years, we have developed an advanced environmental monitoring system (AEMS) containing the eco-sensor, which means a sensor for the measurement of environmental pollutants, based on lipid membranes for continuous monitoring of underground water in industry areas such as semiconductor factories. The AEMS project is composed of three work packages as follows, 1) Eco-sensor, 2) Prediction of plume propagation using a computer simulation technique, and 3) Environmental protection method. In this presentation, we would like to focus on the study of the eco-sensor. The reason why lipid membranes were selected as a sensing element for environmental pollutants is that the pollutants should be interacted with cell membranes because cells are surrounded by cell membranes containing lipid components. Improving the applicability and the responsibility of bilayer lipid membranes (BLMs) in the eco-sensor, we have investigated automatic BLMs preparation devices. An automatic BLMs preparation device was made by use of an inkjet mechanism. The reproducibility of the BLMs preparation was remarkably improved. The sensitivity to volatile organic chlorinated compounds such as cis-1,2-dichloroethylene was in the order of 10 ppb using monoolein BLMs even in real underground water. We have been also developing a smaller sized eco-sensor for the practical use.

A new IR-based sensor technology is introduced for environmental monitoring of industrial pollutants (CO₂, CO, NO_x, etc.). The design concept exploits Si-based, thermally isolated suspended bridge structures. These devices, which function as both IR emitter and detector, are fabricated using MEMS-based processing methods. Photonic bandgap (PBG) modified surfaces enable narrow band IR emission for high chemical selectivity and sensitivity. Spectral tuning is accomplished by controlling symmetry and lattice spacing of the PBG structures. IR spectroscopic studies were used to characterize transmission, absorption and emission spectra in the 2 to 20 micrometers wavelength range. Device characterization studies measured drive and emission power, temperature uniformity, and black body detectivity. Gas detection was achieved using non-dispersive infrared (NDIR) spectroscopic techniques, whereby target gas species and concentrations were determined from comparison to referenced spectra. A sensor system employing the emitter/detector sensor-chip with gas cell and reflective optics is demonstrated and CO₂ gas sensitivity limits are reported. A multi-channel microsensor-array is proposed for multigas (e.g., CO₂, CO, and NO_x, etc.) detection.

New type of the multi-immune sensor was elaborated. It is based on electrolyte-insulator-semiconductors structures and intended for determination of such herbicides as simazine, atrazine and 2,4-D. The specific antibodies were immobilized on nitrocellulose disks, which were placed in measuring cells. The analysis was fulfilled by sequential saturation of antibodies, left unbound after their exposure to native herbicide in investigated sample, with labelled herbicide. If horse radish peroxidase (HRP) was used as label the sensitivity of this multi-immune sensor was about 5 and 1.25 (mu) g/L for simazine and 2,4-D, respectively. At the changing of HRP by (beta) -glucose oxidase the sensitivity of analysis of these herbicides increased approximately in 5 times. The linear plots of the registered concentrations were in the range of 1,0-150,0 and 0,25-150,0 ng/mL for simazine and 2,4-D respectively. It was recommended to use the developed immune sensor for wide screening of herbicides in environment. The ways for increasing of its sensitivity were proposed.

A fast and versatile technique has been developed for detecting small quantities of specific microorganisms or molecules with high specificity. The target analytes are bound to a substrate and placed in the measurement cell of a microscope based on a high-transition temperature Superconducting Quantum Interference Device (SQUID). A solution containing nanometer-size magnetite particles, coated with antibodies specific to the target, is added. The particles, which bind to the target via the antibody- antigen interaction, are superparamagnetic with a Neel relaxation time of ~1s. A pulsed magnetic field aligns the dipole moments, and the SQUID measures the magnetic relaxation signal when the field is turned off. Unbound magnetic particles relax rapidly (~15microsecond(s) ) by Brownian rotation and are not detected. On the other hand, particles bound to targets cannot rotate and instead relax slowly by the Neel mechanism. As a result, only bound particles contribute to the signal, allowing for quantification of the number of targets present without the need for a wash step. The current system can detect as few as 2000 magnetic particles. This technique could be used to detect a wide range of bacteria, viruses, and molecules, with potential applications in the food industry, clinical settings, or research laboratories.

The objectives of this research project are to identify, demonstrate, and validate intelligent systems for conveyance and storage infrastructure that will enable effective, affordable, real-time, remote measurement, analysis, and reporting of their structural health. Specifically, the project involves testing and validating smart pipes, which could indicate locations of structurally weak areas, i.e., where leaks are likely to occur, and the location of existing leaks for corrective action. During the initial phase of this project an extensive literature search was conducted to identify technologies that could potentially be used in intelligent systems. Although the search was primarily focused on new emerging smart technologies, consideration was also given to innovative uses of established structural monitoring or testing technologies. Four emerging technologies that can potentially locate structurally weak areas and predict incipient leaks were identified: electrically conducting composite pipes, electrochemistry-based corrosion sensors, instrumented cathodic protection, and distributed piezoelectric sensors. Also identified was an innovative use of acoustic emission techniques to track deterioration in pre-stressed concrete pipes by monitoring energy releases from breaking corroded pre-stressing wires. A review of each of these technologies is presented. During the next phase of the program one or more of these technologies will be tested and evaluated further.

This paper describes the study of wavelet-based methods employed to de-noise a force transducer signal. This signal was extracted during the extensional deformation of a non-Newtonian polymer fluid. The non-Newtonian polymeric fluid was extensionally deformed with an exponentially increasing velocity profile. This velocity profile corresponded to a specific strain rate. Since the motion was stopped quickly (deceleration time was below 50ms for a complete stop), a serious problem of ringing occurred for approximately one second after the motion has ceased. The ringing manifested itself as a damped harmonic oscillation, which overrides the relaxation characteristics of the molecular structure within the boger fluid. In this paper, our goal was to suppress the damped harmonic oscillatory signal while preserving the relaxation characteristics (decaying exponential signal) of the force data. Several wavelet-based techniques provided acceptable noise suppression while preserving the signal of interest.

This paper addresses the need for a broad-base signal conditioning module designed to process chemical sensor signals in such a way that the output of the conditioning circuits ensures similar baseline and dynamic range, regardless of fabrication variation and sensor drift. These baseline compensation circuits are demonstrated in the context of processing resistance changes from composite polymer chemical sensors and tin-oxide chemical sensors. Because of the initial highly variable baseline state of chemiresistors, a large number of bits in an A/D converter are required to translate the sensor information from an array of these sensors into a digital format for use by a microprocessor. In this work, we present a generic circuit for auto-calibrating and compensating for the baseline of a variety of chemiresistive devices in order to improve concentration measurement resolution and analyte discrimination. The measurement circuits optimize sensor resolution via baseline compensation. Dynamic range is standardized to a constant size regardless of initial baseline resistances. The resulting dynamic range can be as much as two orders smaller than an uncompensated circuit and achieve the same sensor accuracy. Simulations have also shown a factor of 68 improvement in resolution.

The reconstruction of temperature or strain profiles along an optical fiber in Brillouin scattering-based systems, is usually made by directly reading the Brillouin power spectra extracted for each fiber location. Such approach suffers from systematic errors due mainly to nonlocal effects. In this paper, we propose a novel numerical technique for temperature/strain profile reconstructions based on Brillouin optical-fiber time-domain analysis (BOTDA) sensors. In this approach we search directly for the temperature/strain profile along the fiber that matches the measured data. The algorithm is based on an harmonic expansion of the unknown profile, whose coefficients are determined by means of a multidimensional minimization. Several numerical simulations, even in presence of noise, have proved the capability of the proposed algorithm to compensate for systematic errors suffered by classical approaches.

The array biosensor is capable of detecting and identifying multiple analytes in multiple samples simultaneously. Using fluorescence immunoassays on a planar waveguide and miniaturized fluidics, the sensor is automated and portable. Assays are sensitive and require 12 minutes to perform. Environmental contaminants in the sample fail to generate false positive or false negative results in tests performed to date. Measurements can be conducted in real time using spots as small as 80 micrometers . The waveguide can be coated with indium tin oxide (ITO) to create a charged field at the surface to further regulate the interaction of sample components with the surface.

Sensor systems for multi-parameter detection in fluidics usually combine different sensors, which are designed to detect either a physical or (bio-)chemical parameter. Therefore, such systems include a more complicated fabrication technology and measuring set-up. In this work, an ISFET (ion-sensitive field-effect transistor), which is well known as a (bio-)chemical sensor, is utilized as transducer for the detection of both (bio-)chemical and physical parameters. A multifunctional hybrid module for the determination of two (bio-)chemical parameters (pH, penicillin concentration) and three physical parameters (temperature, flow velocity and flow direction) using only two sensor structures, an ion generator and a reference electrode, is realized and its performance has been investigated. Here, a multifunctionality of the sensor system is achieved by means of different sensor arrangements and/or different operation modes. A Ta₂O₅-gate ISFET was used as transducer for all sensors. A novel time-of-flight type ISFET-based flow-velocity (flow rate) and flow-direction sensor using in-situ electrochemical generation of chemical tracers is presented. Due to the fast response of the ISFET (usually in the millisecond range), an ISFET-based flow sensor is suitable for the measurement of the flow velocity in a wide range. With regard to practical applications, pH measurements with this ISFET were performed in rain droplets.

A cell array biosensor was developed, composed of thousands of individual bacteria cells expressing a reporter gene that responds to the presence of environmental pollutants. The single cell array was produced by immobilizing the cells on an optical imaging fiber. A high-density array of microwells was fabricated on the optical imaging fiber's distal face by selectively etching the individual fibers cores. Each microwell was used to accommodate a single living bacterium, allowing simultaneous monitoring of the genetic responses of all the cells in the array. The optical imaging fiber cell array platform provides a powerful tool for the fabrication of whole cell biosensors for various environmental and industrial applications.

A fiberoptical optode array for the in-situ measurement of ground air oxygen concentrations has been used in both, lab and field experiments to monitor subsurface oxygen consumption in a lignite mine tailing affected by acid mine drainage formation. The single sensors are constructed from plastic fibers (core diameter 1 mm) with an oxygen sensitive fluorescent dye film attached to the fiber tip. Measurements were performed with a commercially available oxygen measuring instrument (MICROX 1, PreSens, Regensburg, Germany) which had been modified for the use with 1 mm plastic fibers. The instrument evaluates the oxygen dependent change of the luminescence lifetime of an oxygen indicator using a phase modulation technique. First measurements show a strong oxygen consumption by pyrite oxidation indicated by a ground air oxygen concentration gradient pointing to a depth of approximately 6 m. The measurement of the pyrite depth distribution of the material confirms the assumption that the 40 year old tailing has been depyritized down to a depth of 6 m and that pyrite oxidation and acid mine drainage formation are still going on. Investigations will proceed in order to assess long-term sensor stability under strongly acid conditions.

The surface modification of SAW (surface acoustic wave)- and QCM (quartz crystal microbalance)-devices proves very important in chemical sensing. Silanes on one hand are very useful for hydrophobizing of quartz-surfaces whereas on the other hand thiols are used to adsorb on gold. In this way the influence of humidity on the transducers, which originates in the hydrophilicity of the quartz is decreased. These monolayers not only reduce the cross-sensitivity to water but also enhance the sensor effects of solvent vapors. In order to obtain better selectivity molecular hollows, like calix[n]arenes can be attached to the spacers. Another way to improve the selectivity was found in the treatment of the device with mixtures of silanes and thiols, respectively. In this way cavities are produced in which analytes are incorporated and thus are detected in the lower ppm range. The surface of mass-sensitive devices was also modified in order to detect analytes in the nano- to micrometer range. Here a stamping process with cells yields patterns on polymer surfaces which favor the reinclusion of these microorganisms. These effects are due to geometrical effects and chemical interactions via an adapted polarity and hydrogen bonds of the chosen polymer. The sensor responses proved highly selective to the bacteria in respect to nutrient liquid and other microorganisms.

Magnetoelastic sensors, made of amorphous metallic glass ribbons or wires, have been used to measure various environmental parameters such as temperature, humidity, viscosity, and chemical concentration including pH, carbon dioxide, and ammonia. The parameter of interest is determined by remote detection of the shift in the resonant frequency of the magnetoelastic sensors, which is dependent upon several factors including stress, pressure, temperature, and magnetic field. This paper describes the operating principles of the magnetoelastic sensors and presents several proven applications, as well as methods for optimizing the sensor performance.

We have investigated the effect of ZnO films used as buffer layers on the triboluminescence (TrL) intensity of ZnS:Mn thin films on quartz substrates using RF magnetron sputtering method and annealing technique. Highly oriented film of ZnO was firstly deposited on quartz glass substrate and then the ZnS:Mn film was successfully deposited on the ZnO film with orientation. By annealing at 5% H₂ in Ar ambient, the crystallinity of both ZnO and ZnS:Mn films was increased. It was found that the addition of the ZnO buffer layer greatly improve the TrL intensity of the ZnS:Mn films.

Carbon reservoirs at the earth's surface comprise the plant and microbial, biomass, and organic and inorganic carbon in soils, lakes, rivers, and oceans. These reservoirs interact with the atmosphere and affect its CO₂ content. Soil organic carbon (SOC) is an essential constituent in all ecosystems that can be enhanced by manipulating agricultural and forest lands. A successful strategy is the determination of the amount (quantity) and the chemical composition (quality) of carbon and nitrogen stored within the soil profile. The need for rapid analysis of both the soil quantity and quality is an essential part of determining the techniques of choice for measuring SOC. We have successfully demonstrated the technique of laser-induced breakdown spectroscopy (LIBS) in the determination of the total concentration of carbon and nitrogen in soils and have also been successful in the development of electrochemical-surface enhanced Raman spectroscopy (Electro-SERS), the results for which will be reported in another article. In this article we will focus on the data obtained using the LIBS technique. Our preliminary results suggest that LIBS method can be used for developing a field deployable instrument that can be used for in situ, real time monitoring of total carbon and nitrogen in soil. We have determined the total concentration of carbon in 15 soil samples and have obtained a calibration curve for them.

We present a unique method for routine monitoring of polycylic aromatic hydrocarbons in water samples. Significant innovations include a rapid solid-liquid extraction procedure, a cryogenic fiber optic probe for fluorescence measurements in frozen matrices at liquid helium temperature (4.2 K) and an instrumental system for laser-excited time-resolved Shpol'skii spectrometry. The potential of this methodology is illustrated with the direct trace analysis of fifteen Environmental Protection Agency priority pollutants in less than 5 minutes.

Results for optimizing an array of composite polymer gas sensors for sensing one of five analytes in the presence of up to four interferents are presented. The optimized array consists of a heterogeneous array of up to ten points (unlike sensors) in multi-dimensional sensor space. The optimization techniques presented here are linear, since the composite polymer sensors in their useful (low concentration) operating range exhibit linear and additive response characteristics. The optimization of these arrays produces maximum separability between analytes, demonstrating the trade-off between the addition of both information and variability induced by increasing the size of the heterogeneous array. Optimization results for sensing acetone, hexane, thf, toluene, and ethanol in the presence of interferents result in array sizes that are significantly less than the maximum available number of sensors (10). This result adds fuel to the argument that fewer sensors are better; the argument for more sensors is also made in the context of the electronic nose systems where significant chemical diversity is required.

Principal component analysis and regression (PCA, PCR) are widespread algorithms for the calibration of spectrometers and the evaluation of spectra. In many applications, however, there are huge amounts of calibration data, as it is common to hyperspectral imaging for instance. Such data sets consist often of several ten thousands of spectra measured at several hundred wavelength positions. Hence, a PCA of calibration sets that large is computational very time consuming - in particular the included singular value decomposition (SVD). Since this procedure takes several hours of computation time on conventional personal computers, its calculation is often not feasible. In this paper a straightforward acceleration of the PCA is presented, which is achieved by data preprocessing consisting of three steps: data compression based on a wavelet transformation, exclusion of redundant data, and by taking advantage of the matrix dimensions. Since the size of the calibration matrix determines the calculation time of the PCA, a reduction of its size enables the acceleration. Due to an appropriate data preprocessing, the PCA of the discussed examples could be accelerated by more than one order of magnitude. It is demonstrated by means of synthetically generated spectra as well as by experimental data that after preprocessing the PCA results in calibration models, which are comparable to the ones obtained by the conventional approach.

Due to the MOdular Luminescence Lifetime Imaging system (MOLLI)that has been developed within the last few years it is possible to use oxygen sensors that are not optically isolated. Transparent planar optodes and dispersed nano-optodes for the first time enable a direct optical link between the chemical parameter to be measured (oxygen as an example) and the structure that is responsible for the distribution of the chemical parameter (ascidian and corals as an example). Since the transparency as a principal quality of the optode allows to record structural images. The spatial resolution of the MOLLI imaging system is determined by a)the area size of the view field that is imaged onto the amount of pixels of the CCD-chip (640x480 in our case)and b)by the spatial limitations of the sensing layer. The latter means in case of the planar optode the thickness of the sensing layer and in case of dispersed nano-optodes the thickness of the excitation light field. We present biological applications of transparent planar optodes (thickness approximately equals 5-10 micrometers ) at two areal resolutions,a)50 micrometers /pixel and b)6 micrometers /pixel and one application of nano-optodes at 80 micrometers /pixel. The first application shows the oxygen production of endolithic cells that live in the skeleton of massive corals measured in a cut coral sample that was illuminated through the planar oxygen optode with defined light energy levels to follow the oxygen production of these coral symbionts. Finally the oxygen production and consumption of coral symbionts are shown by dispersed oxygen nano-optodes in the medium. The specific set-up for the latter experiment will be discussed with the future implication of possible 3D measurements. Although the results all come from biological applications from coral reef environments obviously the measuring system and the transparent sensors can be applied to a variety of environmental topics. At the moment similar optodes are under development for parameters like pH,CO₂ and temperature.

The results presented in this paper demonstrate the possibility of using tin dioxide films as sensitive elements for alcohol sensors. The tin dioxide films were deposited by the spray pyrolysis method on alumina substrates as well as on n⁺ porous silicon upper layer of silicon diode structures. Room temperature, under atmospheric pressure measurements of the parameters of the obtained structures revealed their high sensitivity to the mixture of ethyl alcohol vapors and air. The optimum concentration of precursor solution for precipitation of tin dioxide films and technological regimes for the deposition of tin dioxide films and formation of a porous silicon layer with appropriate thickness and porosity by electrochemical anodization were found.

In order to develop the sensor system for environmental monitoring, chemical sensors using quartz crystal microbalance (QCM) coated with acrylate-film with different functional groups, and styrene-film as a molecular recognition membrane are prepared using plasma-polymerized chemical vapor deposition (CVD) method. It is found that the sensor response for various gases strongly depends on the functional group of molecular recognition membrane of the sensor. The styrene-film coated sensor exhibits no selectivity for specific gas and responds to various gases. It is also found that the styrene-film coated sensor in conjunction with principal component analysis is useful for identification of gas kinds in environmental monitoring.

The development of a field-portable Raman instrument for environmental analyses is described. It is based on the use of a near-infrared frequency-stabilized diode laser for excitation, an acousto-optic tunable filter for wavelength selection, and an avalanche photodiode for detection. Evaluation of this instrument for the monitoring of environmentally important species will be discussed as well as its ability to be operated in room light without significantly increasing the background signal. In addition, we will also describe a baseline removal procedure based on second derivative approach that simplifies and increases the accuracy of the instrument's automated identification algorithm.

In recent years, we have developed an advanced environmental monitoring system (AEMS) containing the eco-sensor, which means a sensor for the measurement of environmental pollutants, based on lipid membranes for continuous monitoring of underground water in industry areas such as semiconductor factories. The AEMS project is composed of three work packages followed by 1)Eco-sensor, 2)Prediction of plume propagation using a computer simulation technique, and 3)Environmental protection method. In this presentation, we would like to focus on the study of the eco-sensor. The reason why lipid membranes selected as a sensing element for environmental pollutants is that the pollutants should be interacted with cell membranes because cells are surrounded by cell membranes containing lipid components. Improving the applicability and the responsibility of bilayer lipid membranes (BLMs) in the eco-sensor, we have investigated the automatic BLMs preparation device. An automatic BLMs preparation was remarkably improved. The sensitivity to volatile organic chlorinated compounds such as cis-1,2-dichloroethylene was in the order of 10ppb using the monoolein BLMs even in real underground water. We also have been developing a smaller sized eco-sensor for the practical use.