Numerical analysis of thermal lens effect for sensitive detection on microchips

Anraku, Ryo; Mawatari, Kazuma; Tokeshi, Manabu; Nara, Masatoshi; Asai, Toru; Hattori, Akihiko; Kitamori, Takehiko

doi:10.1002/elps.200700571

Cited by 10 publications

(4 citation statements)

References 22 publications

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“…To date, we have developed basic and general concepts for micro-integration by micro unit operations (MUO) and continuous-flow chemical processing (CFCP) utilizing pressure driven flow and our innovative sensitive detector of nonfluorescent molecules, the thermal lens microscope (TLM). [1][2][3][4][5][6][7][8][9] The control and stabilization of multiphase flow is also a significant development. These basic concepts have led to the successful integration of various analytical systems on microchips for use in environmental, food and cell analysis.…”

Section: Introductionmentioning

confidence: 99%

Microchip-based cell analysis and clinical diagnosis system

Sato¹,

Mawatari²,

Kitamori³

2008

Lab Chip

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Cell analysis and clinical diagnosis systems are now becoming the largest field of application for microchip-based analytical systems. Technological advantages include: small volume, fast analysis time, highly integrated analytical functions, easy operation and small size. For these purposes, basic methodologies for general micro-integration and basic technologies, including fluidic control and ultrasensitive detection, are required. In this review, we introduce our approach to the general integration of various analytical functions and the application of cell analysis systems with cultured cells in microchannels, as well as practical analytical systems for clinical diagnosis utilizing human serum samples.

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Section: Introductionmentioning

confidence: 99%

Microchip-based cell analysis and clinical diagnosis system

Sato¹,

Mawatari²,

Kitamori³

2008

Lab Chip

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“…Figure shows the 3D geometry of a nanochannel, and the probe and excitation beam profiles used for the simulation. The source term Q ( r , z , t ) of the heat conduction equation due to the focused excitation beam is described as follows. , Here, P [W/m 2 ] is the excitation power, α [m –1 ] is the absorption coefficient, f [Hz] is the modulation frequency, ω 0,ex [m] is the beam waist radius, and z r,ex [m] is the Rayleigh length of the excitation beam. After solving the heat conduction equation in the time-dependent mode, the change in refractive index multiplied by the intensity of the focused probe beam is integrated as follows …”

Section: Methodsmentioning

confidence: 99%

“…The source term Q(r, z, t) of the heat conduction equation due to the focused excitation beam is described as follows. 28,29…”

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confidence: 99%

Thermo-optical Characterization of Photothermal Optical Phase Shift Detection in Extended-Nano Channels and UV Detection of Biomolecules

et al. 2017

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The expansion of microfluidics research to nanofluidics requires absolutely sensitive and universal detection methods. Photothermal detection, which utilizes optical absorption and nonradiative relaxation, is promising for the sensitive detection of nonlabeled biomolecules in nanofluidic channels. We have previously developed a photothermal optical phase shift (POPS) detection method to detect nonfluorescent molecules sensitively, while a rapid decrease of the sensitivity in nanochannels and the introduction of an ultraviolet (UV) excitation system were issues to be addressed. In the present study, our primary aim is to characterize the POPS signal in terms of the thermo-optical properties and quantitatively evaluate the causes for the decrease in sensitivity. The UV excitation system is then introduced into the POPS detector to realize the sensitive detection of nonlabeled biomolecules. The UV-POPS detection system is designed and constructed from scratch based on a symmetric microscope. The results of simulations and experiments reveal that the sensitivity decreases due to a reduction of the detection volume, dissipation of the heat, and cancellation of the changes in the refractive indices. Finally, determination of the concentration of a nonlabeled protein (bovine serum albumin) is performed in a very thin 900 nm deep nanochannel. As a result, the limit of detection (LOD) is 2.3 μM (600 molecules in the 440 attoliter detection volume), which is as low as that previously obtained for our visible POPS detector. UV-POPS detection is thus expected be a powerful technique for the study of biomolecules, including DNAs and proteins confined in nanofluidic channels.

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“…18 Indeed, PTL has been utilized for the extraction of minor amounts of the radionuclides [19][20][21] such as uranium, 22 americium 23 and plutonium, 24 and the advantages of the reduced waste and sample consumption were highlighted. For online detectors, although a thermal lens microscope (TML) has been utilized successfully for the online detection of various metals extracted by PTL, 25,26 this technique suffers from the lack of selectivity of metal species. 14,27 As a result, ICP-MS remains the most promising candidate for the online measurement of multi-elements.…”

Section: Introductionmentioning

confidence: 99%