1. www.parksystems.com
Aplicaciones de la Microscopia de Fuerza
Atómica
Dra. Gabriela Mendoza. Científica en aplicaciones, Park Systems, Inc.
Agosto 30, 2019
2. Park Systems es un fabricante líder mundial de
Microscopios de Fuerza Atómica y Sistemas de
Microscopía de Nanoescala Emergentes.
3. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 3
Park Systems suministra una amplia gama de AFM que son
adecuados para diversas aplicaciones en el mercado
4. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 4
Linea de productos Park AFM
AFM Investigación AFM industrial
- Plataforma común: escáner desacoplado
- True Non-Contact
- Automatización SmartScan
5. Mayor precision – La más alta resolución – Fácil de usar
5
Escaner Park AFM
Escáner XY y Z desacoplados
Tecnologia Park AFM
Modo: True Non-Contact™
Park SmartScan™
6. Contenido
6Confidential and Proprietary, Park Systems
Aplicaciones
Modos de operación
Aplicación en NCM
Aplicación en SICM
Aplicación con modo PinPoint
Aplicación en LFM
10. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 10
Topografia en NCM. Matriz polimerica
10
512 x 512 px
NCM
Si cantilever
Adaptive scan
NX10
50 x 50 um 25 x 25 um 10 x 10 um
11. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 1111
Topografia 5 x 5 um Fase 5 x 5 um
Topografia y fase
512 x 512 px
NCM
Cantilever Si
Adaptive scan
NX10
12. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 12
XEI. Análisis de perfil de líneas
12
Dx=0.856 um
Dx=1.341 um
Dx=1.000 um
Dy=320 nm
Dy=369 nm
Dy=496 nm
Topography 5 x 5 um
13. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 13
XEI. Análisis de granos
13
Length =1.539 um
Length = 1.242 um
Topography 5um x 5um
*Peak to valley roughness (Rpv), Root mean square roughness (Rq), Roughness average (Ra)
Graph
16. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 16
SICM
Técnica de no contacto
Nano pipeta con solución
electrolítica
La corriente iónica dependiente
de la distancia se utiliza como
retroalimentación.
• Falta de especificidad química
SECM
Información electroquímica
El microelectrodo escanea
lateralmente a través del sustrato
mapea la reactividad de la
superficie
Corriente Faradaica oxidación
o reducción
Sistema de retroalimentación
• Incrementar especificidad química
• Retroalimentación precisa para el control de
distancia de la superficie de la sonda
SICM-SECM hibrido
17. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 17
SICM-SECM Sonda
Depósito térmico
10 nm Cr/250 nm
Au
Depósito químico de
vapor Dichloro-p-
xylylene
FIB
Shi, W.; Baker, L. A. RSC Adv. 2015, 5, 99284-99290.
Pipeta de
cuarzo
18. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 18
SICM-SECM Setup con Park NX10
NX Controlador
Amperimetro
Corriente Faradaica
a AUX IN 2
Corriente ionica
como feedback
SICMSECM
Cabezal SICM
PE
RE
AuE
Pipeta: 100 mM KCl
Bano: 100 mM KCl + 10 mM
Ru(NH3)6
3+
Potencial: -0.5 V
Muestra: Barras de oro sobre Pyrex
Oro sobre sustrato de Pyrex
• Ancho: 10 um
• Paso: 20 um
• Altura: 300 nm
20. Contenido
20Confidential and Proprietary, Park Systems
Aplicaciones
Modos de operación
Aplicación en NCM
Aplicación en SICM
Aplicación con modo PinPoint
Aplicación en LFM
23. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 23
Propiedades nanomecánicas
Energía de adhesión Fuerza de adhesion Altura
Superficie 1
Superficie 2
Superficie 3
La adhesión de bacterias se basa en la
interacción física entre dos o mas superficies
24. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 24
Propiedades nanomecánicas
Energia de adhesion
Fuerza de adhesion
Altura
Energía de adhesión y fuerza de
adhesión tuvieron un comportamiento
similar
Los valores mas bajos se observaron
para la bacteria comparados con el
sustrato. Lo anterior indica que se
requiere menos fuerza sobre la
bacteria
La bacteria aislada en aire es menos
adhesiva que el sustrato.
400 aJ
200 aJ
45 nN
20 nN
Chip de silicio Bacteria
Energia de adhesion Fuerza de adhesion Altura
27. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 27
LFM
Se mide la deflexión en dirección
horizontal
La deflexión lateral del cantilever
ocurre como resultado de la fuerza
encontrada por el cantilever mientras
escanea horizontalmente a lo largo
de la superficie de la muestra.
Los factores que determinan la
magnitud de esta deflexión incluyen:
– Coeficiente de fricción
– Topografía de la superficie de la
muestra
– Dirección de escaneo
– Spring constant lateral
28. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 28
Muestra 1
Polímero sobre vidrio
256 px x 256 px
20 um x 20 um
1 Hz
LFM Forward LFM BackwardTopo
29. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 29
Muestra 2
Grafeno sobre silicio
LFM & SThM
256 px x 256 px
15 um x 15 um
0.6 Hz
LFM SThMTopo
31. Park Systems www.parksystems.com
Copyright Park Systems Corp., All rights reserved. 31
Eventos próximos
Workshop Colombia Septiembre 11 y 12
Medellín: Universidad Nacional de Colombia
Medellin: Universidad EAFIT
XVIII MRS Meeting. Balneário Camboriú, Brazil. Septiembre 22-26
Before we get started, I will give you a brief introduction about Park Systems
Park Systems is a world-leading manufacture of atomic force microscopes, and emerging nanoscale microscopy systems,
Our product line covers just about every usage case with fully manual to fully automated cases.
As you can see here, from XE7 to NX-Hivac for research uses on topo
And from NX-HDM to NX-3DM in our industrial systems.
And our AFM technology offers the best accuracy, the highest resolution, and, is the easiest to use on market
Now, after the short introductory remarks about our company, let’s get started.
Here is a brief outline for today’s presentation:
As you may know, AFM has a wide variety of applications in diverse fields such as materials, electronics, manufacture, nanotechnology and last but not least life science. On the right hand side we can see AFM images from collagen fibers, topography of muscle fiber, cellular surface morphology
Let’s recap,
For SICM, a distance-dependent ion current is used as feedback, which provides a very robust probe-substrate distance control. Powerful as it is, SICM does not have any chemical specificity.
For SECM, on the other hand, uses Faradaic current originated from either the oxidation or reduction of the electrochemical species in solution. With SECM, the electrochemical activity map of the surface under study can be obtained. However, the drawback in SECM lies in the fact that feedback-controlled probe positioning is complicated by the different Faradaic current behavior over conductive and insulative substrates. In conventional SECM measurements, constant-height imaging is used, in which the tip is maintained at a constant height from the surface and the faradaic current is recorded. In constant-height SECM imaging, when variations in surface topography and reactivity occurs concurrently, the data interpretation becomes problematic.
So, if we can have combine SICM and SECM together, the hybrid SICM-SECM technique will have the robust probe position control from SICM, and also have the chemical specificity from SECM.
Now, the question is, how to do that?
OK, so this is the fabrication approach for the probes we employed for this SICM-SECM expt.
We start with a quartz pipette, we pull it to an opening diameter of tens of nm. This is a scanning transmission electron microscopy (STEM) of a pipette, and this is the one pipette that we carried through the whole process.
A Cr adhesion layer followed by a Au layer was thermally deposited on the quartz surface. So we end up with a quartz pipette with a portion of it coated with a conductive gold layer, and that’s shown here in this STEM image. We then overcoat this Au-coated pipette with a layer of parylene C. You can now see from the STEM image, here is the Au layer, here is the parylene layer that’s over coating the entire pipette. Finally we take this pipette to a focus ion beam, or FIB, what FIB will allow you to do is essentially do nanoscale sculpting. We chop off the end of the tip and expose the gold layer here and the nanopore here.
So we now have a central pore that’s useful for doing SICM
And this electrode that’s in a cresent shape, this gold crescent electrode can be used to record faradaic electron transfer.
Here in the center we measure ion transfer, like K+, Cl-
And electron transfer is measured at this gold electrode.
Here is the electron micrograph of the final probe, here is the pipette in the center, and here is the gold crescent electrode, and here is the parylene coating on the outside.
Now the reason why we want to use a parylene coating is we want to limit the active electrode area to this small crescent around the tip. If we did not put this coating on the outside, the active electrode area will be the entire gold layer around the pipette, we will be measuring the electrochemical response everywhere around the pipette as oppose to just the tip.
To give you a better idea of how we realize the SICM-SECM experiment. I have here the cartoon illustration of the instrument setup and the real-life photograph of the setup side by side.
In the schematic illustration, we have an ammeter connected to the Au crescent electrode, the measured Faradaic current is then fed to the auxillary ADC channel of the AFM controller, which will then enable the user to monitor and record the Faradaic current with the software.
In the photo, SICM-SECM experiment performed with a Park NX10 system is shown. Here is the SICM-SECM probe. A IC clip is connected to the Au part to make electrical connection for SECM measurement.
For SICM measurement, we have a pipette electrode back-inserted into the nanopipette here, and the reference electrode in the bath solution here.
In the petri-dish, we have the SICM-SECM standard sample immersed in the bath solution.
So what is the SICM-SECM standard sample?
Now, after the short introductory remarks about our company, let’s get started.
Here is a brief outline for today’s presentation:
Adhesion energy and adhesion force images of a single bacteria as well as 3D topographical image were obtained at the same time on the NX-10 using PinPoint mode.
The coloring of each pixel representing the elasticity and the adhesion map was determined from the calculation generated by PinPoint FD curve at each pixel.
3D topography shows exact positional match with the FD spectroscopy maps.
Bacterial adhesion is based on physical interactions between two or more surfaces.
If we consider the tip on the cantilever as surface 1, bacteria as surface 2, and the silicon wafer as surface 3. All three surfaces have different physicochemical properties: surface area, surface energy, surface roughness size and shape, which affect the adhesion force and energy.
The adhesion energy and adhesion force behaved in a similar manner; smaller values were observed for the bacteria compared with the substrate where they were attached.
The isolated bacteria in air is observed to be relatively less adhesive than that of the underlying Si substrate.
The test results show that the probiotic bacteria under study were less adhesive to the Si cantilever tip compared to the Si substrate. This phenomenon can be correlated with the adhesion of probiotic strains to the site of action, an important prerequisite for probiotic action.
If you want to learn more, please visit Parksystems.com for more information
With that I want to thank you for your attention. Richard?