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Fabrication of QCM sensor array and PDMS micro chamber for biosensor applications
(2009-10-22)
Jaruwongrungsee, K.
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Maturos, T.
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Wong-ek, K.
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Sangworasil, M.
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Pintavirooj, C.
In this work, an array of quartz crystal microbalance (QCM) sensors is fabricated on a single quartz crystal substrate and attached with poly(dimethylsiloxane) (PDMS) micro chamber for using in flow-injection system. The Cr/Au electrode array is deposited on both side of quartz substrate by sputtering through electroplated microshadow mask. PDMS micro chamber was fabricated by mold casting technique with SU-8 mold. Fabricated PDMS micro chamber and QCM sensor array were attached together for using in flow-injection system. In our experiment, the QCM electrodes were coated with the carboxylic poly(vinyl chloride) (PVC-COOH) and then the carboxylic group was activated with carbodiimide hydrochloride (EDC) and N-hydroxylsuccinimide (NHS) for protein binding. The scanning electron micrograph shown the trapped protein on the modified sensing layer, it confirmed that our QCM sensor and PDMS micro chamber can be used as QCM biosensor array. This new QCM sensor array provide possibility of multiple detection in small amount of sample within a single quartz crystal substrate that avoid the error signal from the different properties of each sensor in an array. ©2009 IEEE.
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Low cost hot embossing process for plastics microfluidic chips fabrication
(2009-10-22)
Lomas, T.
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Mongpraneet, S.
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Wisitsoraat, A.
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Jaruwongrungsee, K.
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Sappat, A.
In this work, we develop plastic microfluidic chips based on low cost hot embossing process with metal micromold. Metal micromold was formed on aluminum substrates by CNC milling machine and high precision micromachine. The hot embossing system is in-house made with computer aid design by Solid Work program. The system consists of four main parts, structural body, heating system, compressive system and control electronics. The compressive system consists of two top hydraulic single-stage pistons and four middle-stage pistons. Polymethyl methacrylate (PMMA) microfluidic chips were then produced by hot embossing under different applied temperatures and time. It was found that optimum temperature and time for minimum contraction and depth error were 80 degree C and 2-5 minutes. The developed technique offer advantages for microfluidic chip fabrication in term of quality, complexity and cost. ©2009 IEEE.
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Comparison study of ultrasonic diffraction tomography and ultrasonic non-diffraction tomography
(2007-01-01)
Onemanisone, Thongsamlith
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Pintavirooj, C.
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Jaruwongrungsee, K.
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Sangworasil, Manas
Diffraction tomography is a technique for imaging with acoustic fields in which parameter, such as reflective index, sound velocity, etc., can be mapped from scatter wave resulting from insonifying the object with a plane wave at a single temporal frequency. By solving the direct scattering problem, the scattered field can be presented in term of scattering parameters. Different inversion techniques can be applied to takes advantage of the linearization process of the nonlinear wave equation describing wave propagation in heterogeneous media under for limited class of scattering. Specifically, when the scattering effect is weak, one can invoke the Born or Rytov approximation and thus derive the generalized Fourier Slice Theorem to reconstruct the cross-section of the insonified object. The objective of this paper is to compare the quality of the reconstructed image derived from diffraction tomography and non-diffraction tomography.
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Ultrasonic reflection mode tomography using frequency-shift method
(2006-12-01)
Tosranon, P.
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Onemanisone, T.
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Greesuradej, P.
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Pintavirooj, C.
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Jaruwongrungsee, K.
Tomogram of the soft tissue can be reconstructed by using its projections resolved from the ultrasonic broadband pulsed waves which are passed through the tissue. While a data from ultrasonic transmission mode tomography cannot be used to image the character of soft tissue where shadowed by a bone, an ultrasonic reflection mode tomography is realized to be a solution for this. There are many ways to extract the projections, in most case the integrated attenuation coefficients of the tissue from the pulsed wave. Almost all of these methods were proved to implement with the transmission mode signal, but however, some adaptation may takes benefit from those method to implement with the reflection mode. We choose the frequency-shift method to be analyzed because its advantage in a computational viewpoint. The simple filtered backprojection algorithm was implemented to reconstruct the tomographic images of the soft tissue suffered by bone. The results are shown the successful of this method over the transmission mode tomography. Also the simulations for noisy data were analyzed. © 2006 IEEE.
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Ultrasonic diffraction tomography: The experimental result
(2005-12-01)
Pintavirooj, C.
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Jaruwongrungsee, K.
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Withayachumnankul, W.
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Hamamoto, K.
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Daochai, S.
Diffraction tomography is a technique for imaging with acoustic fields. It takes advantage of the linearization process of the non-linear wave equation describing wave propagation in heterogeneous media. When the scattering effect is weak, one can invoke the Born or Rytov approximation and thus derive the generalized Fourier Slice Theorem to reconstruct the cross-section of the insonified object. Although diffraction tomography is a promising technology for medical application as it provides a quantitative ultrasonic image, its realization toward medical use is still far-to-go, this may be due to the complexity of the hardware involved. In this research we investigate a potential use of diffraction tomography for medical application by using a delicate-designed ultrasonic computerized tomographic system. The result of experiment investigation of diffraction tomography is very promising. Copyright UNION Agency - Science Press.
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Ultrasonic refractive index and sound velocity tomography
(2004-12-01)
Pintavirooj, C.
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Jaruwongrungsee, K.
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Withayachumnankul, W.
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Hamamoto, K.
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Taertulakarn, S.
Ultrasonic computed tomography (UCT) is one of the methods capable of tissue characterization. It is expected to provide not only a quantitative image but also diagnostic information. As in X-ray CT, UCT requires a projection data to reconstruct a cross-sectional image. The projection data of Ultrasonic Tomography is based on measurement the time delay, which is time difference between ultrasound traverse with and without object. In this paper, we investigate two different types of quantitative UCT image, refractive-index and sound-velocity image. We purpose the new method of measurement the time delay by converting the received ultrasonic pulse to frequency domain and measuring the phase shift of the center frequency of the broadband pulse. The method seems more robust to noise. Two image reconstruction techniques are used for comparison purpose including traditional filtered back-projection and simultaneous algebraic reconstruction technique (SART). © 2004 IEEE.

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