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ABSTRACT: In this paper, a shear force scanning near-field fluorescence microscope combined with a confocal laser microspectrofluorometer is described. The shear force detection is realized based on a bimorph cantilever, which provides a very sensitive, reliable, and easy to use method to control the probe-sample distance during scanning. With the system, high-quality shear force imaging of various samples has been carried out. Furthermore, simultaneous shear force and near-field fluorescence imaging of biological cells has also been realized. As an example, we especially present the result on the distribution of P-glycoprotein in the plasma membrane of human small cell lung cancer cells, suggesting that the system would be a promising tool for biological applications.
Ultramicroscopy 12/2005; 105(1-4):324-9. · 2.47 Impact Factor
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ABSTRACT: A non-optical bimorph-based tapping-mode force sensing method for tip-sample distance control in scanning near-field optical microscopy is developed. Tapping-mode force sensing is accomplished by use of a suitable piezoelectric bimorph cantilever, attaching an optical fibre tip to the extremity of the cantilever free end and fixing the guiding portion of the fibre to a stationary part near the tip to decouple it from the cantilever. This method is mainly characterized by the use of a bimorph, which carries out simultaneous excitation and detection of mechanical vibration at its resonance frequency owing to piezoelectric and anti-piezoelectric effects, resulting in simplicity, compactness, ease of implementation and lack of parasitic optical background. In conjugation with a commercially available SPM controller, tapping-mode images of various samples, such as gratings, human breast adenocarcinoma cells, red blood cells and a close-packed layer of 220-nm polystyrene spheres, have been obtained. Furthermore, topographic and near-field optical images of a layer of polystyrene spheres have also been taken simultaneously. The results suggest that the tapping-mode set-up described here is reliable and sensitive, and shows promise for biological applications.
Journal of Microscopy 09/2004; 215(Pt 2):127-30. · 1.63 Impact Factor
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ABSTRACT: Near-field fluorescence spectra with subdiffraction limit spatial resolution have been taken in the proximity of mitochondrial membrane inside breast adenocarcinoma cells (MCF7) treated with the fluorescent dye (JC-1) by using a scanning near-field optical microscope coupled with a confocal laser microspectrofluorometer. The probe–sample distance control is based on a piezoelectric bimorph shear force sensor having a static spring constant k = 5 μN/nm and a quality factor Q = 40 in a physiological medium of viscosity η = 1.0 cp. The sensitivity of the force sensor has been tested by imaging a MCF7 cell surface. © 2001 American Institute of Physics.
Applied Physics Letters 10/2001; 79(15):2489-2491. · 3.84 Impact Factor
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ABSTRACT: In this article we present a simple, nonoptical shear force detection scheme to control probe–sample distance for a scanning near-field optical microscope (SNOM). Shear force detection is realized by attaching a tapered optical fiber probe to a piezoelectric bimorph cantilever in which one piezo layer generates a maximum piezo voltage when the cantilever is excited at resonance by the other piezo layer. The amplitude of the piezo voltage will decrease as the probe approaches a sample's surface due to probe–sample interacting shear force. Keeping the piezo voltage constant provides a very sensitive method by which to control probe–sample distance. Based on the shear force detection scheme, a shear force SNOM system has been built, operating in transmission collection mode. Shear force topographic and optical images have been taken using uncoated optical fiber probes fabricated by a chemical etching technique. The results suggest that the system is very reliable, repeatable, and easy to use. © 2001 American Institute of Physics.
Review of Scientific Instruments 04/2001; 72(5):2344-2349. · 1.37 Impact Factor
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ABSTRACT: In this paper, a shear force scanning near-field fluorescence microscope combined with a confocal laser microspectrofluorometer is described. The shear force detection is realized based on a bimorph cantilever, which provides a very sensitive, reliable, and easy to use method to control the probe–sample distance during scanning. With the system, high-quality shear force imaging of various samples has been carried out. Furthermore, simultaneous shear force and near-field fluorescence imaging of biological cells has also been realized. As an example, we especially present the result on the distribution of P-glycoprotein in the plasma membrane of human small cell lung cancer cells, suggesting that the system would be a promising tool for biological applications.
Ultramicroscopy.
