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.
LMEN, UFR des Sciences, Université de Reims Champagne-Ardenne, 21 rue Clement Ader, 51685 Reims 2, France.
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Shang
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Lei
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Troyon
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Trussardi-Regnier
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Manfait
D004912:Erythrocytes / Q000648:ultrastructure*; D006801:Humans; D008855:Microscopy, Electron, Scanning / Q000379:methods; D014732:Vibration