Armote Somboonkaew

Development of surface plasmon resonance imaging for detection of Acidovorax avenae subsp. citrulli (Aac) using specific monoclonal antibody

An immunosensor based on surface plasmon resonance imaging (SPR imaging) using a specific monoclonal antibody 11E5 (MAb 11E5) was developed for the detection of the seed-borne bacterium Acidovorax avenae subsp. citrulli (Aac), which causes fruit blotch in watermelons and cantaloupes, and compared to the conventional ELISA technique. The 1:40 mixed self-assembled monolayer (mixed SAM) surface was used for the immobilized MAb 11E5 on sensor surface for the detection of Aac. Both whole cells and broken cells of Aac were tested by using direct and sandwich detection assay. The limit of detection (LOD) of Aac using the SPR imaging technique and a direct detection assay was 10(6)cfu/ml and a subsequent amplification of the SPR signal using a polyclonal antibody (PAb) lowered the LOD to 5×10(5) cfu/ml. The LOD for the ELISA technique was 5×10(4) cfu/ml for the detection of Aac, which was slightly better than that for the SPR technique. However, the sensor surface based on SPR imaging offered a major advantage in terms of surface regeneration, allowing at least five cycles with a shorter time assay, multi-channel analysis with an application on multiplex detection, and an ease of the surface usage for the detection of Aac in the naturally infected plant. The surface was tested against the naturally infected sample and showed good selectivity toward the Aac bacteria.

ABO blood-typing using an antibody array technique based on surface plasmon resonance imaging.

In this study, readily available antibodies that are used in standard agglutination tests were evaluated for their use in ABO blood typing by a surface plasmon resonance imaging (SPR imaging) technique. Five groups of antibodies, including mixed clones of anti-A, anti-B, and anti-AB, and single clones of anti-A and anti-B, were used to construct the five-line detection arrays using a multichannel flow cell in the SPR imager. The red blood cell (RBC) samples were applied to a multichannel flow cell that was orthogonal to the detection line arrays for blood group typing. We found that the blood samples were correctly grouped in less than 12 min by the SPR imaging technique, and the results were consistent with those of the standard agglutination technique for all 60 samples. We found that mixed clones of antibodies provided 33%–68% greater change in the SPR signal than the single-clone antibodies. Applying the SPR imaging technique using readily available antibodies may reduce the costs of the antibodies, shorten the measurement time, and increase the throughput.

Low-cost cell-phone-based digital lux meter

The amount of light is an important issue in several scenarios ranging from scenic design, light pollution study, illumination engineering, and agriculture. It is typically determined by using a portable digital light or lux meter. By realizing that the proliferation of cell phones is currently tremendous, this paper proposes for the first time a low-cost cell phone based digital light meter. Our innovative idea comes from the fact that the digital camera built into the cell phone is functioned as a two-dimensional light sensitive device and the captured image can be made diffuse. In this way, the diffused image is correlated to the corresponding light level by the built-in microprocessor of the cell phone and our specific algorithm embedded. Our experiment using a typical cell phone embedded with a digital camera and our JAVA program will be discussed.

Thermal analyzer enables improved lie detection in criminal-suspect interrogations

The conventional polygraph, or lie detector, has long been used for questioning criminal suspects and even in some job interviews. The polygraph is based on a century-old system involving analysis of a person’s involuntary psychophysiological responses to questions. Signals from sensors placed on the person’s arm, fingers, chest, and abdomen detect changes in variables such as breathing and pulse rates, blood pressure, and perspiration. Information from the sensors was once recorded on a moving strip of paper but is now usually stored digitally. However, a major drawback of the standard polygraph test is its intrusive nature, which makes the subject anxious and uncomfortable and can, thus, affect the accuracy of the responses. An innocent but very nervous individual can fail a polygraph test. Conversely, the system can be defeated by a clever suspect. Therefore, development of noninvasive and more trustworthy lie-detection methods has become a highly desirable goal. One of the more promising technologies for application to lie detection is thermal imaging. Since 2006, our team has developed and demonstrated1–5 a system we call the thermal analyzer for deception detection (TAD2). It analyzes far-IR data obtained remotely from a suspect’s periorbital (around the eyes) and nostril areas during interrogation. With this data, a measured change in skin temperature from the two periorbital areas is converted to a relative blood-flow velocity. At the same time, the system deduces the person’s respiration pattern from measured temperature changes around the nostrils (see Figure 1). TAD2’s only required instrumentation is a thermal-imaging camera that is sensitive to the far-IR spectrum (i.e., 7.5–13 mwavelength bands) and a laptop computer. The camera is placed in front of the subject and oriented such that the person’s head Figure 1. Far-IR skin-temperature (Ts) data from a subject’s (a) periorbital and (b) nostril areas. The data reveals the person’s relative bloodflow velocity (Vs) and breathing rate, respectively. dt: Time interval.

Rh blood phenotyping (D, E, e, C, c) microarrays using multichannel surface plasmon resonance imaging

The application of Surface Plasmon Resonance Imaging (SPRi) for the detection of transmembrane antigen of the Rhesus (Rh) blood group system is demonstrated. Clinically significant Rh blood group system antigens, including D, C, E, c, and e, can be simultaneously identified via solid phase immobilization assay, which offers significant time savings and assay simplification. Red blood cells (RBCs) flowed through the micro-channel, where a suitable condition for Rh blood group detection was an RBC dilution of 1:10 with a stop-flow condition. Stop flow showed an improvement in specific binding compared to continuous flow. Rh antigens required a longer incubation time to react with the immobilized antibody than A and B antigens due to the difference in antigen type and their location on the RBC. The interaction between the immobilized antibodies and their specific antigenic counterpart on the RBC showed a significant difference in RBC removal behavior using shear flow, measured from the decay of the SPR signal. The strength of the interaction between the immobilized antibody and RBC antigen was determined from the minimum wall shear stress required to start the decay process in the SPR signal. For a given range of immobilized antibody surface densities, the Rh antigen possesses a stronger interaction than A, B, and AB antigens. Identification of 82 samples of ABO and Rh blood groups using SPRi showed good agreement with the standard micro-column agglutination technique. A wider coverage of antigenic recognition for RBC when using the solid phase immobilization assay was demonstrated for the RBC with the antigenic site located on the transmembrane protein of the clinically significant Rh antigen. Given the level of accuracy and precision, the technique showed potential for the detection of the Rh minor blood group system.

Application of surface plasmon resonance biosensor for the detection of Candida albicans

In this study, surface plasmon resonance imaging (SPR imaging) was developed for the detection of Candida albicans which is a causal agent of oral infection. The detection was based on the sandwich assay. The capture antibody was covalently immobilized on the mixed self assemble monolayers (SAMs). The ratio of mixed SAMs between 11-mercaptoundecanoic acid and 3-mercaptopropanol was varied to find the optimal ratio for use as a sensor surface. The results showed that the suitable surface for C. albicans detection was SAM of carboxylic (mixed SAMs ), even though mixed SAMs had a high detection signal in comparison to mixed SAMs , but the non-specific signal was higher. The detection limit was 107 cells/ml for direct detection, and was increased to 106 cells/ml with sandwich antibody. The use of polyclonal C. albicans antibody as capture and sandwich antibody showed good selectivity against the relevant oral bacteria including Escherichia coli, Streptococcus mutan, Staphylococcus aureus, β-streptococci, and Lactobacillus casei. SPR platform in this study could detect C. albicans from the mixed microbial suspension without requirement of skillful technician. This SPR imaging biosensor could be applied for Candida identification after cultivation.

Development and Beam-Shape Analysis of an Integrated Fiber-Optic Confocal Probe for High-Precision Central Thickness Measurement of Small-Radius Lenses

This work describes a new design of a fiber-optic confocal probe suitable for measuring the central thicknesses of small-radius optical lenses or similar objects. The proposed confocal probe utilizes an integrated camera that functions as a shape-encoded position-sensing device. The confocal signal for thickness measurement and beam-shape data for off-axis measurement can be simultaneously acquired using the proposed probe. Placing the probe’s focal point off-center relative to a sample’s vertex produces a non-circular image at the camera’s image plane that closely resembles an ellipse for small displacements. We were able to precisely position the confocal probe’s focal point relative to the vertex point of a ball lens with a radius of 2.5 mm, with a lateral resolution of 1.2 µm. The reflected beam shape based on partial blocking by an aperture was analyzed and verified experimentally. The proposed confocal probe offers a low-cost, high-precision technique, an alternative to a high-cost three-dimensional surface profiler, for tight quality control of small optical lenses during the manufacturing process.

Simultaneous Analysis of Far Infrared Signals From Periorbital and Nostril Areas for Nonintrusive Lie Detection: Performance From Real Case Study

This paper highlights our simultaneous analysis of two-dimensional far-infrared data around the two periorbital and the nostril areas for nonintrusively evaluating the deception level of the subject. In our proposed approach, measured changes in maximum skin temperatures around two periorbital regions are converted to the change in the relative blood flow velocity. A signature of the respiration pattern is also simultaneously determined in terms of the ratio of the measured maximum and minimum temperatures in the nostril area. Our simultaneous analysis of these two far-infrared signatures is similar to the standard polygraph test in that more than one of our involuntary reflexes is examined at once. Our two-year field test study covers 18 examination tests on subjects who are suspected in involving in real crime cases in Thailand. Based on our automatic baseline classification and scoring criteria, we obtain a promising classification rate of 88.9%, which is about 10% improvement compared to our analysis using far-infrared data from either the periorbital or nostril area alone.

Fiber-optic confocal probe with an integrated real-time apex finder for high-precision center thickness measurement of ball lenses

This paper describes the development of a fiber-optic confocal probe suitable to measuring the central thickness of highcurvature small-diameter optical ball lenses. The confocal probe utilizes an integrated camera that functions as a realtime apex-sensing device. An additional camera is used to monitor the shape of the reflected light beam. Placing the instrument sensing spot off-center from the apex will produce a non-circular image at the camera plane that closely resembles an ellipse for small displacement. By analyzing the shape of the reflected light spot, we are able to precisely determine the focus point of the confocal probe relative to the apex point to better than 2-μm precision for ball lenses with diameters in the range of 3 – 10 mm. The proposed confocal probe offers a low-cost alternative technique for quality control of ball lenses during the manufacturing process.

Face detection in thermal imagery using an Open Source Computer Vision library

This paper studies the use of a combination of Haar-like features and a cascade of boosted tree classifiers embedded in a widely used OpenCV for face detection in thermal images. With 2013 positive and 2020 negative 320×240-pixel thermal images for 20 training stages on three window sizes of 20×20, 24×24, and 30×30 pixels, our experiment shows that these three windows offer similar hit and false alarm rates at the end of the training section. Larger windows also spend much more time to train. During our testing, the 30×30-pixel window provides measured best hit and false rejection/acceptation rates of 93.4% and 6.6%, respectively, with a measured slowest detection speed of 19.6 ms. A 5-ms improvement in the measured detection speed with a slightly lower hit rate of 92.1% is accomplished by using the 24×24-pixel window. These results verify that the combination of Haar-like features and a cascade of boosted tree classifiers is a promising technique for face detection application in thermal images.