Thermal lens microscopy

Thermal lens microscopy (TLM) is a type of photothermal spectroscopy. TLM depends on the coaxial focusing of the excitation and probe laser beams (see Figure 7.20). Which is achieved using the chromatic aberration of a microscopic objective lens [731]. The excitation beam can be provided by a YAG laser (532 nm) [846,1021] or an Ar ion laser (514.5 nm [846] or 488 nm [732]).The probe beam can be provided by a He-Ne laser (632.8 nm) [846,1021], After optical excitation of the analyte molecules, radiationless relaxation of the analytes occurs,... 

In another report, the release of cytochrome c from mitochondria to cytosol in neuroblastoma-glioma hybrid cells was studied on a quartz chip. The released cytochrome c was measured by scanning thermal lens microscopy [851]. 

Sato, K., Kawanishi, H., Tokeshi, M., Sub-zeptomole detection in a microfabricated glass channel by thermal-lens microscopy. Anal. Sci. 1999, 15, 525. 

Kim, H.B., Hagino, T., Sasaki, N., Kitamori, T., Ultrasensitive detection of electrochemical reactions by thermal lens microscopy for microchip chemistry. Micro Total Analysis Systems 2003, Proceedings 7th flTAS 2003 Symposium, Squaw Valley, CA, Oct. 5-9, 2003, 817-820. 

TIRFM total internal reflection fluorescence microscopy TLM thermal lens microscopy... 

We have developed a novel ultrasensitive detection method, thermal lens microscopy (TLM), for nonfluorescent species [13]. TLM is photothermal spectroscopy under an optical microscope. Our thermal lens microscope (TLM) has a dual-beam configuration excitation and probe beams [13]. The wavelength of the excitation beam is selected to coincide with an absorption band of the target molecule and that of the probe beam is chosen to be where the sample solution (both solvent and solute) has no absorption. For example, in determination of methyl red dye in water, cyclohexane, and n-octanol, a 514-nm emission line of an argon-ion laser and a 633-nm emission line of a helium-neon laser were used as excitation and probe beams, respectively [21], Figure 4 shows the configuration and principle of TLM [13]. The excitation beam was modulated at 1 kHz by an optical chopper. After the beam diameters were expanded, the excitation and probe beams were made coaxial by a dichroic mirror just before they were introduced into an objective lens whose magnification and numerical aper-... 

Figure 2 Schematic of thermal lens microscopy (TLM). (Reprinted with permission from Ref. 8.)...

Minagawa, T., Tokeshi, M. and Kitamori, T., Integration of a wet analysis system on a glass chip determination of Co(n) as 2-nitroso-l -naphthol chelates by solvent extraction and thermal lens microscopy. Lab Chip, 1, 72, 2001. 

On the other hand, spectroscopic detection methods, such as laser-induced fluorescence, UV/Vis absorption, chemiluminescence, and thermal lens microscopy, have been used for on-chip detection. Among these methods, the fluorescence detection method has been most widely used because of its high sensitivity and low detection limits for biologically relevant species. However, the fluorescence detection technique has some disadvantages. Many chemical... 

Kitamori T, Tokeshi M, Sato K, Hibara A (2004) Thermal lens microscopy and microchip chemistry. Anal Chem 76 52A... 

Kim H-B, Hagino T, Sasaki N, Watanabe N, Kitamori T (2005) Spectrochemical detection using thermal lens microscopy with a glass-substrate microelectrode-microchannel chip. J Electroanal Chem 577 47... 

Cell characterization can be optical (performed by optical and fluorescent techniques, imaging with nanoparticles or thermal lens microscopy), biochemical (using ion-selective microelectrodes), or a combination of both (Lidke et al., 2004 Choi et al., 2009 Tamaki et al., 2002 Guenat et al., 2006 Cheng et al., 2006). The possibility to fabricate sensing structures at nanoscale, such as nanoelectrodes or nanowires, allows the possibility of subcellular and intracellular measurements (Tong etal., 2009). 

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