Name: atomic force microscopy for surface mapping
Uploaded: 2023-04-30T12:00:37.000Z
Duration: 1 min 8 s
Channel: JoVE

A microscopia de força atômica ou AFM gera uma imagem usando uma nanossonda para fornecer informações topográficas sobre uma amostra com resolução nanométrica.
Quando um microscópio ótico puder ampliar até 1000X, o potencial da ampliação de AFM é até 1.000.000X.
O AFM pode criar imagens de espécimes fixos e vivos, permitindo capturar processos celulares dinâmicos, como a dinâmica da actina.
A ponta de prova do AFM é unida à extremidade de um modilhão flexível, e junto fazem a varredura a amostra. A sonda segue os contornos da superfície da amostra, movendo-se para cima e para baixo, o que desloca o cantilever.
Em um tipo de AFM, um feixe de laser é apontado para o cantilever e, à medida que se move, o reflexo do laser também se move.
Um fotodetector sensível à posição registra a deflexão do feixe de laser.
Os dados são enviados para um computador onde o software pode processá-los para gerar uma imagem tridimensional da superfície da amostra.

<ol>
	<li>Casuso, Ignacio, Felix Rico e Simon Scheuring. "AFM biológico: de onde viemos - onde estamos - para onde podemos ir." Jornal de Reconhecimento Molecular 24.3 (2011): 406-413.</li>
	<li>Garcína, Ricardo e Rubén Perez. "Métodos dinâmicos de microscopia de força atômica." Relatórios de ciência de superfície 47.6-8 (2002): 197-301.</li>
</ol>

microscopia de força atômica

Atomic Force Microscopy

A microscopia de força atômica (AFM) é um tipo de microscopia de varredura por sonda que pode analisar detalhes topográficos de várias amostras, como cerâmica, vidro, polímeros e amostras biológicas. A AFM oferece resolução 1000 vezes maior que o sistema de imagem óptica. As imagens geradas a partir da AFM são perfis de superfície tridimensionais, oferecendo uma vantagem sobre as imagens planas e bidimensionais de outras técnicas de imagem. A Sonda AFM A sonda é considerada o coração de qualquer configuração AFM, e compreende o cantilever e o conjunto da ponta. As sondas são a peça mais comumente substituída neste tipo de microscópio porque a interação constante com as amostras desgasta a ponta. Portanto, a escolha do material para a sonda depende das propriedades da amostra. As sondas de silício, usadas para analisar amostras duras, são mais rígidas e nítidas do que as sondas de nitreto de silício, que são mais adequadas para digitalizar amostras mais macias. Essas pontas afiadas são produzidas usando gravação eletroquímica ou nanotubos de carbono para análises de maior precisão. Modos de imagem da AFM Na AFM, a topografia da superfície é estudada usando a interação entre a ponta da sonda e a superfície da amostra. Existem dois modos principais de imagem – um modo estático, também conhecido como modo de contato, e um modo dinâmico. No modo estático, ou de contato, a ponta da sonda fica em contato contínuo com a superfície da amostra. À medida que a ponta se arrasta sobre a superfície, forças repulsivas entre a amostra e a ponta resultam na flexão do cantilever, que é registrada. Toda a superfície da amostra é escaneada para frente e para trás nos eixos x e y, na chamada varredura raster, enquanto o movimento vertical do cantilever registra o eixo z, gerando assim uma imagem 3D. No modo dinâmico, a sonda oscila logo acima da superfície da amostra, aproximando-se da superfície, mas sem tocá-la. As forças atrativas e repulsivas determinam a variação na distância entre a ponta e a amostra, afetando a amplitude de oscilação do cantilever. Este feedback é registrado para construir a topografia da superfície da amostra.

Microscopia de Força Atômica

A microscopia atômica da força (AFM) é um tipo de microscopia da ponta de prova da exploração que possa analisar detalhes topográficos de vários espécimes ...

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Cell Biology

Biologia Celular

Unit 1

Unidade 1

Visualizing Cells, Tissues, and Molecules

Visualizando Células, Tecidos e Moléculas

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

atomic force microscopy for surface mapping

Atomic force microscopy is used to map the surface details of materials. It can examine ceramics, glass, polymers, and biological samples. The method gives far more resolution than an optical imaging system and produces three-dimensional surface profiles instead of flat 2D images.

The probe is the key part of an AFM setup. It includes the cantilever and tip assembly, and it is also the part that is replaced most often. Constant contact with samples wears down the tip, so probe choice depends on the sample being scanned. Silicon probes are stiffer and sharper, which makes them useful for hard samples. Silicon nitride probes are better for softer samples.

AFM tips can be made with electrochemical etching or with carbon nanotubes to improve accuracy. The microscope reads surface topography by tracking how the probe tip interacts with the sample surface. This interaction is recorded as the probe scans across the surface.

AFM uses two main imaging modes. In static mode, also called contact mode, the tip stays in continuous contact with the surface. As it drags across the sample, repulsive forces bend the cantilever, and that bending is recorded. The sample is scanned back and forth in the x- and y-axes, which is called raster scanning, while the vertical motion of the cantilever records the z-axis and builds a 3D image.

In dynamic mode, the probe oscillates just above the sample surface. It comes close to the surface without touching it. Attractive and repulsive forces change the distance between the tip and the sample and affect the oscillation amplitude. That feedback is then used to construct the surface topography.

Atomic Force Microscopy for Surface Mapping

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Atomic force microscopy is used to map the surface details of materials. It can examine ceramics, glass, polymers, and biological samples. The method gives far more resolution than an optical imaging system and produces three-dimensional surface profiles instead of flat 2D images. The probe is the key part of an AFM setup. It includes the cantilever and tip assembly, and it is also the part that is replaced most often. Constant contact with samples wears down the tip, so probe choice depends...

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key terms and concepts

Learn how atomic force microscopy maps surfaces, why probe choice matters, and how contact and dynamic modes build detailed 3D images of samples.

Atomic Force Microscopy for Surface Mapping | JoVE K12

cell biology

JoVE Core - Biologia Celular ilustra processos celulares complexos em vídeos de animação fáceis de entender e, ao mesmo tempo, abrangentes. Esta coleção foca nos componentes e funções essenciais das células, incluindo organelas e membranas, transporte celular e energia celular. É complementado por vídeos de Cientistas em ação que demonstram a aplicação da biologia celular em experimentos de pesquisa do mundo real.

Atomic Force Microscopy for Surface Mapping

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