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

La microscopía de fuerza atómica o AFM genera una imagen utilizando una nanosonda para proporcionar información topográfica sobre una muestra con una resolución nanométrica.
Mientras que un microscopio óptico puede aumentar hasta 1000X, el potencial de aumento de AFM es de hasta 1.000.000X.
AFM puede crear imágenes de especímenes fijos y vivos, lo que le permite capturar procesos celulares dinámicos como la dinámica de actina.
La nanosonda AFM está unida al extremo de un voladizo flexible y juntos escanean la muestra. La sonda sigue los contornos de la superficie de la muestra, moviéndose hacia arriba y hacia abajo, lo que desplaza el voladizo.
En un tipo de AFM, un rayo láser se dirige al voladizo y, a medida que se mueve, el reflejo del láser también se mueve.
Un fotodetector sensible a la posición registra la desviación del rayo láser.
Los datos se envían a una computadora donde el software puede procesarlos para generar una imagen tridimensional de la superficie de la muestra.

<ol>
	<li>Casuso, Ignacio, Félix Rico y Simón Scheuring. "AFM biológico: de dónde venimos, dónde estamos, hacia dónde podemos ir". Revista de Reconocimiento Molecular 24.3 (2011): 406-413.</li>
	<li>García, Ricardo y Rubén Pérez. "Métodos de microscopía dinámica de fuerza atómica". Surface science reports 47.6-8 (2002): 197-301.</li>
</ol>

fuerza atómica microscópica

Atomic Force Microscopy

La microscopía de fuerza atómica (AFM) es un tipo de microscopía de sonda de barrido que puede analizar detalles topográficos de diversas muestras como cerámica, vidrio, polímeros y muestras biológicas. AFM ofrece más de 1000 veces más resolución que el sistema de imágenes ópticas. Las imágenes generadas por AFM son perfiles de superficie tridimensionales, lo que ofrece una ventaja sobre las imágenes planas bidimensionales de otras técnicas de imágenes.

La sonda AFM

La sonda se considera el corazón de cualquier configuración de AFM y comprende el conjunto de punta y voladizo. Las sondas son la pieza que se reemplaza con más frecuencia en este tipo de microscopio porque la interacción constante con las muestras desgasta la punta. Por tanto, la elección del material para la sonda depende de las propiedades de la muestra. Las sondas de silicio, utilizadas para analizar muestras duras, son más rígidas y afiladas que las sondas de nitruro de silicio, que son más adecuadas para escanear muestras más blandas. Estas puntas afiladas se producen mediante grabado electroquímico o nanotubos de carbono para un análisis de mayor precisión.

Modos de imagen de AFM

En AFM, la topografía de la superficie se estudia mediante la interacción entre la punta de la sonda y la superficie de la muestra. Hay dos modos de imagen principales: un modo estático, también conocido como modo de contacto, y un modo dinámico.

En el modo estático o de contacto, la punta de la sonda está en contacto continuo con la superficie de la muestra. A medida que la punta se arrastra sobre la superficie, las fuerzas repulsivas entre la muestra y la punta provocan la curvatura del voladizo, que se registra. Toda la superficie de la muestra se escanea hacia adelante y hacia atrás en los ejes x e y, lo que se denomina escaneo rasterizado, mientras que el movimiento vertical del voladizo registra el eje z, generando así una imagen 3D.

En el modo dinámico, la sonda oscila justo por encima de la superficie de la muestra, acercándose a la superficie, pero sin tocarla. Las fuerzas de atracción y repulsión determinan la variación en la distancia entre la punta y la muestra, afectando la amplitud de la oscilación del voladizo. Esta retroalimentación se registra para construir la topografía de la superficie de la muestra.

Fuerza atómica microscópica

La microscopía de fuerza atómica (AFM) es un tipo de microscopía de sonda de barrido que puede analizar detalles topográficos de diversos especímenes como cerámica, vidrio, ...

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Cell Biology

Biología Celular

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Visualizing Cells, Tissues, and Molecules

Visualización de células, tejidos y moléculas

KEY TERMS AND CONCEPTS

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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

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

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JoVE Core Biología Celular ilustra procesos celulares complejos mediante completos vídeos animados fáciles de entender. Esta colección se centra en los componentes esenciales de las células y su funcionamiento, incluyendo los orgánulos y las membranas, el transporte celular y el metabolismo energético celular. Todo este material se complementa con los vídeos de científicos en acción, que muestran la aplicación de la biología celular en experimentos reales de investigación.

Atomic Force Microscopy for Surface Mapping

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