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Nano Thermal and Contact Potential Analysis with Heated Probe TipsRemmert, Jessica Lynn 09 April 2007 (has links)
This work describes two closed-loop atomic force microscopy methods that utilize the heated silicon probe to interrogate surfaces. The first method identifies the softening temperatures of a selected polymer and organic substrate as a function of contact force and surface hardness. Motivation partly stems from nanosampling, which requires knowledge of phase-specific transitions to identify and extract mass from multicomponent systems for chemical analysis. In the second method, the cantilever is implemented as a Kelvin probe to study the effect of temperature on the measured contact potential. The objective is to ascertain whether the probe functions as a capable electrode for scanning Kelvin probe microscopy (SKPM) applications. This was achieved by performing heated force-distance experiments on a biased gold film with the tip operating at various potentials. Both experiments examine the interaction between the tip and substrate and analyze sample effects both induced and sensed by the cantilever.
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Análise do potencial de calibração da força óptica através de dispositivos de microscopia de força atômica / Analysis of the calibration potential of optical force through atomic force microscopy devicesMarques, Gustavo Pires, 1978- 20 August 2018 (has links)
Orientador: Carlos Lenz Cesar / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-20T14:50:59Z (GMT). No. of bitstreams: 1
Marques_GustavoPires_M.pdf: 1771357 bytes, checksum: 8ee6919633e2615608f25b33bec98e96 (MD5)
Previous issue date: 2005 / Resumo: O microscópio de força atômica é uma ferramenta que possibilita a medida de forças precisamente localizadas com resoluções no tempo, espaço e força jamais vistas. No coração deste instrumento está um sensor a base de uma viga (cantilever) que é responsável pelas características fundamentais do AFM. O objetivo desta pesquisa foi usar a deflexão deste cantilever para obter uma calibração rápida e precisa da força da armadilha da pinça óptica, assim como testar e comparar com os método tradicionalmente utilizados para este propósito. Para isso, foi necessário analisar e entender o condicionamento de sinais utilizados no AFM. Foram estudados cantilever tradicionais, cujo sistema de detecção é baseado na deflexão de um feixe laser em conjunto com fotodetectores, bem como cantilevers piezoresistivos. Cantilevers piezoresistivos fornecem uma alternativa simples e conveniente aos cantilevers ópticos. A integração de um elemento sensorial dentro do cantilever elimina a necessidade de um laser externo e de um detector utilizados na maioria dos AFMs. Isto elimina a etapa delicada de alinhamento da laser ao cantilever e fotodetector que normalmente precede uma medida com AFM, uma simplificação que expande o potencial do AFM para o uso em meios adversos, como câmaras de ultra alto vácuo ou, como no caso específico das Pinças Ópticas, onde existem esferas em solução líquida e também restrições de dimensão / Abstract: The atomic force microscope (AFM) is a tool that enables the measurement of precisely localized forces with unprecedented resolution in time, space and force. At the heart of this instrument is a cantilever probe that sets the fundamental features of the AFM. The objective of this research has been using the deflection of this cantilever to get a fast and accurate calibration of optical tweezers trap force, as well as testing and comparing to the traditionally used methods of calibration for this purpose. For that it was necessary to resolve and understand the sensors signals conditioning used in the AFM. Traditional cantilevers, whose detection system is based on the deflection of a laser beam in addition with a photodetector, as well as piezoresistive cantilevers has been studied. Piezoresistive cantilevers provide a simple and convenient alternative to optically detected cantilevers. Integration of a sensing element into the cantilever eliminates the need for the external laser and detector used in most AFMs. This removes the delicate step of aligning the laser to the cantilever and photodetector which usually precedes an AFM measurement, a simplification which expands the potential of the AFM for use in difficult environments such as ultrahigh vacuum chambers or, as in Optical Tweezers specific case, where there are spheres into a liquid solution as well as dimensional constraints / Mestrado / Física / Mestre em Física
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