Biomedical subjects

M Troyon

Publications and source records attributed to M Troyon.

5 recordsLinked to original sources

PubMed2005

Development of a shear force scanning near-field fluorescence microscope for biological applications.

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.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2004

Non-optical bimorph-based tapping-mode force sensing method for scanning near-field optical microscopy.

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.

Erythrocytes↗

PubMed2004

Shear force near-field optical microscope based on Q-controlled bimorph sensor for biological imaging in liquid.

Shear force near-field microscopy on biological samples in their physiological environment loses considerable sensitivity and resolution as a result of liquid viscous damping. Using a bimorph-based cantilever sensor incorporating force feedback, as recently developed by us, gives an alternative force detection scheme for biological imaging in liquid. The dynamics and sensitivity of this sensor were theoretically and experimentally discussed. Driving the bimorph cantilever close to its resonance frequency with appropriate force feedback allows us to obtain a quality factor (Q-factor) of up to 10(3) in water, without changing its intrinsic resonance frequency and spring constant. Thus, the force detection sensitivity is improved. Shear force imaging on mouse brain sections and human skin tissues in liquid with an enhanced Q-factor of 410 have shown a high sensitivity and stability. A resolution of about 50 nm has been obtained. The experimental results suggest that the system is reliable and particularly suitable for biological cell imaging in a liquid environment.

Animals↗

PubMed2000

Cathodoluminescence imaging and spectroscopy by near-field detection

Using near-field techniques, we have developed an experimental set-up for spatially resolved cathodoluminescence (CL) spectroscopy and monochromatic imaging. It combines a scanning near-field optical/force microscope with a scanning electron microscope equipped with a field emission gun. The potentialities of this scanning near-field cathodoluminescence microscope are demonstrated on two kinds of sample: an indented MgO crystal and AlGaN/GaN quantum wells grown on GaN/sapphire. Monochromatic CL imaging allows a clear distinction between the emission of quantum wells and the GaN substrate, and for the MgO crystal, the localization on the slip bands, near the indentation, of luminescent centres emitting at 450 nm.

Journal Article↗

PubMed1989

Magnetic field emission gun with zirconiated emitter.

A magnetic-field-superimposed field emission gun with low aberrations and equipped with a zirconiated tungsten emitter has been developed for applications where very stable high probe currents are required. It has been tested on a conventional electron microscope at 10 kV and on an electron beam testing system at 1 kV. Probe current i = 250 nA in a probe size d = 0.4 micron is obtained at 10 kV; at 1 kV the resolution is 0.1 micron with i = 5 nA, and 0.4 micron with i = 30 nA. For these probe currents, the spatial broadening effect due to electron-electron interactions in the beam is the preponderant factor limiting the probe size.

Magnetics↗