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Author: search.filters.author.Pechprasarn, SuejitSubject: search.filters.subject.Instrumentation

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    Analysis of effects of surface roughness on sensing performance of surface plasmon resonance detection for refractive index sensing application
    (2021-09-01)
    Treebupachatsakul, Treesukon
    ;
    Shinnakerdchoke, Siratchakrit
    ;
    Pechprasarn, Suejit
    This paper provides a theoretical framework to analyze and quantify roughness effects on sensing performance parameters of surface plasmon resonance measurements. Rigorous coupled-wave analysis and the Monte Carlo method were applied to compute plasmonic reflectance spectra for different surface roughness profiles. The rough surfaces were generated using the low pass frequency filtering method. Different coating and surface treatments and their reported root‐mean-square roughness in the literature were extracted and investigated in this study to calculate the refractive index sensing performance parameters, including sensitivity, full width at half maximum, plasmonic dip intensity, plasmonic dip position, and figure of merit. Here, we propose a figure‐of-merit equation considering optical intensity contrast and signal‐to‐noise ratio. The proposed figure-of‐merit equation could predict a similar refractive index sensing performance compared to experimental results reported in the literature. The surface roughness height strongly affected all the performance parameters, resulting in a degraded figure of merit for surface plasmon resonance measurement.
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    Performance analysis of non‐interferometry based surface plasmon resonance microscopes
    (2021-08-01)
    Tontarawongsa, Sorawit
    ;
    Visitsattapongse, Sarinporn
    ;
    Pechprasarn, Suejit
    Surface plasmon microscopy has been of interest to the science and engineering commu-nity and has been utilized in broad aspects of applications and studies, including biochemical sensing and biomolecular binding kinetics. The benefits of surface plasmon microscopy include label‐free detec-tion, high sensitivity, and quantitative measurements. Here, a theoretical framework to analyze and com-pare several non‐interferometric surface plasmon microscopes is proposed. The scope of the study is to (1) identify the strengths and weaknesses in each surface plasmon microscopes reported in the literature; (2) quantify their performance in terms of spatial imaging resolution, imaging contrast, sensitivity, and measurement accuracy for quantitative and non‐quantitative imaging modes of the microscopes. Six types of non‐interferometric microscopes were included in this study: annulus aperture scanning, half annulus aperture scanning, single‐point scanning, double‐point scanning, single‐point scanning, at 45 degrees azimuthal angle, and double‐point scanning at 45 degrees azimuthal angle. For non‐quantitative imaging, there is a substantial tradeoff between the image contrast and the spatial resolution. For the quantitative imaging, the half annulus aperture provided the highest sensitivity of 127.058 rad/μm<sup>2</sup> RIU<sup>−1</sup>, followed by the full annulus aperture of 126.318 rad/μm<sup>2</sup> RIU<sup>−1</sup>. There is a clear tradeoff between spatial resolution and sensitivity. The annulus aperture and half annulus aperture had an optimal resolution, sensitivity, and crosstalk compared to the other non‐interferometric surface plasmon resonance micro-scopes. The resolution depends strongly on the propagation length of the surface plasmons rather than the numerical aperture of the objective lens. For imaging and sensing purposes, the recommended mi-crofluidic channel size and protein stamping size for surface plasmon resonance experiments is at least 25 μm for accurate plasmonic measurements.
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    Item type:Publication,
    Low-cost instrumentation of Automated Whole - Slide Microscope for Biomedical Imaging
    (2019-01-10)
    Pechprasarn, Suejit
    ;
    Sukkasem, Chayanisa
    ;
    Suvarnaphaet, Phitsini
    ;
    Thongchoom, Rujirada
    ;
    Chuwittaya, Suteeboon
    Microscope is one of the essential devices in medical profession. It is usually used for finding out types of abnormal cells or tissues, detecting the diseases, and defining a range treatment option for patient. Recently, there is a new technology of whole-slide imaging (WSI) which has been developed in the microscope. The technology provides the scanning of conventional glass slides to produce digital images of cumulative data. Since the WSI is a complex system and very expensive price, hence we aim to implement the prototype of a cost- effective whole - slide imaging system based on the principle of microscopic design. The implemented prototype consisting of optical and mechanical parts was developed using 3D printing. The optical system employed a 40x objective lens aligning with the digital camera for imaging the specimen on the standard slide. The mechanical system was designed for the movement of the slide in 3 dimensions automatically and controlled by stepper motors and microcontrollers based on controlling computer program. To accumulate the whole- slide image, the slide was scanned and captured in the X-Y axes and the focal (Z) axis in a sequence. The cumulative data was then analyzed and rendered the whole- slide image. The implemented device would be advantageous to cytologists and doctors for the biomedical imaging and recording numerous medical data of the patients.