Photonic crystals in biology - NanoTR-VI

Poster Session, Thursday, June 17Theme F686 - N1123High Resolution AFM imaging in Liquid EnvironmentÜmit Çelik 1 , Demet Catcat 2 , H. Ozgur Ozer 3 , Ahmet Oral 41 Department of Materials Engineering, Istanbul Technical University, 34469, Turkey2 NanoMagnetics Instruments Ltd., 266 Banbury Road, Oxford OX2 7DL, UK.3 Department of Physics Engineering, Istanbul Technical University, Istanbul, 34469, Turkey4 Faculty of Engineering & Natural Sciences, Sabanci University, Istanbul, 34956, TurkeyAbstract – We developed a low noise atomic force microscope which can achieve high resolution imaging in liquidenvironment. We designed a tube piezoelectric scanner that can achieve atomic resolution sensitivity with 2 m scan range.We have worked on noise reduction in laser source and optical feedback noise. We used optical beam deflection method(OBD) method to measure deflection of cantilever and we worked on noise reduction in ODB sensor. In this study we willpresent the major noise sources in ODB method with theoretical and practical experimental comparison results.We have developed a high resolution afm which canoperate in liquid. This method offers the opportunityfor the visualization individual mobile molecules inreal-time as well as in real space under physiologicalenvironment at the molecular level. Spatial resolutionis very important issue in biological moleculesimaging, because biological molecules is generally at afew nanometers size. Recently, there has been a greatprogress in improving the spatial resolution fordynamic-mode in-liquid AFM [1, 2].In this work, we used SPM control electronic whichis supplied by NanoMagnetics Instruments Ltd.Firstly, we ensured that the scanner is working properlyfor atomic resolution imaging. We designed a tubepiezo scanner and made its characterization. Weanalysed frequnecy spectra of mechanical response ofthe scanner. We tested our scanner in air using contactmode afm and we achieved atomic resolution on micasurface(figure 1).The low noise characteristic of the deflection sensormakes it possible toobtain a maximum frequencysensitivity limited by the thermal Brownian motion ofthe cantilever(figure 2) in every environment[1]. Wedesigned a low noise deflection sensor and we didtheoritical and practical comparisons.Figure 2. Brownian motion of the cantilever with 350MHz Rfinjection in the air environmentThis work is supported by TÜBTAK andNanoMagnetics Instruments ltd.References:[1] T. Fukuma, K. Kobayashi, K. Matsushige, H. Yamada,True molecular resolution in liquid by frequency-modulationatomic force microscopy, Appl. Phys. Lett. 86 (2005)193108.[2] T. Fukuma, M. J. Higgins, S. P. Jarvis, Direct imaging oflipid-ion network formation under physiological conditionsby frequency modulation atomic force microscopy, Phys.Rev. Lett. 98 (2007) 106101.Figure 1. Atomic resolution image on mica surface.We have worked on laser noise reduction. The rfmodulation considerably reduces the mode hoppinginduced by the optical feedback. In addition, themultimode laser beam has a lower coherence than thesingle-mode does. Thus, the rf modulation also workswell to suppress the optical interference noise[1]. Wehave injected diffrent rf frequency with diffrentamplitudes to laser diode and we tried to find optimumconditions. We have also tried different commerciallaser diodes to make a comparison between them.6th Nanoscience and Nanotechnology Conference, zmir, 2010 665