The Technology Behind Atomic Force Microscopes

The technology behind atomic force microscopes has been developed by pioneering scientists and engineers at leading technology firms, government labs, and universities throughout the world. AFMs continue to evolve and advance as scientists require higher resolution topographic scanning

Atomic Force Microscope Technology

Light Lever Force Sensor

The light lever force sensor had its origins in the work of precision engineers working on surface profilers. In 1932, Smaltz presented a light lever stylus profile that used film to record the movement of a sharp probe as it scanned across a surface. This technique was first applied to AFM by Amer, an IBM scientist. The light lever force sensor is now the standard in AFM designs.

Vibrating Mode AFM

As with the light lever force sensor, vibrating probe instruments were developed first for surface profilers. It was discovered that by vibrating the probe above a surface as it was scanned, lateral forces on the probe were reduced. Although Binnig and Quate discussed vibrating modes in their pioneering paper, it was a team of IBM scientists led by Kumar Wickramsinghe that first applied vibrating techniques to the AFM. Wickramsinghe’s group found that they were able to make the technique sensitive enough that they did not have to tap the surface. The AFMWorkshop does not recommend tapping the surface in vibrating mode AFM. This is possible using the technology developed by IBM scientists.

**The Technology Behind Atomic Force Microscopy**

Feedback Circuits

The first scanning tunneling microscope developed at IBM in Switzerland utilized analog feedback to control the relationship between the probe and surface while measuring an image. This is very similar to the pioneering work of Young at the NBS. Soon after that pioneers such as A. Lewis built scanning probe microscopes with digital feedback. However, because of the limitations of ADC and DAC converters, AFM Workshop uses high-fidelity analog feedback circuits to control the Z position of the probe/sample in its microscopes.

Re-Trace Technology

In a scanning probe microscope it is often advantageous to store height information while scanning a sample. This stored information can then be used for a following scan to hold the probe at a fixed distance above a sample’s surface. This technique was pioneered by University of Texas professor Alan Bard.

For a more complete introduction to Atomic Force Microscopy, we recommend Atomic Force Microscopy, by Peter Eaton and Paul West, published by Oxford University Press.

To learn more about atomic force microscopy, feel free to visit www.afmworkshop.com.

Advantages Of Using AFMs For Nanoparticle Characterization

The Atomic Force Microscope (AFM) allows for 3D characterization of nanoparticles with sub-nanometer resolution. Nanoparticle characterization using Atomic Force Microscopy has a number of advantages over dynamic light scattering, electron microscopy and optical characterization methods.

Nanoparticle Characterization Overview

Unique advantages of AFM nanoparticle characterization include

Characterization of nanoparticles that are .5 nm in diameter and larger.
Nanoparticle mixture distributions below 30 nm.
Characterization of variable geometry nanoparticles.
Direct visualization of hydrated nanoparticles/liquid medium.
Characterization of nanoparticle physical properties such as magnetic fields.
Analysis of the size of nanoparticles.

Nanoparticles over 0.5 nm in diameter
An outstanding feature of the Atomic Force Microscope is that it can directly create images of nanoparticles with dimensions between 0.5 nm and 50+ nm. Nanoparticle size distributions are directly calculated from AFM images.
Nanoparticle Mixture Distributions below 30 nm
AFMs can easily identify and characterize bimodal distributions of nanoparticles. AFMWorkshop’s built-in nanoparticle analysis software makes nanoparticle characterization fast and easy.

Variable geometry nanoparticles
AFM can evaluate variable nanoparticle geometry, from traditional spherical nanoparticles to more exotic fractal geometries of nanoparticle clusters.
Hydrated Samples/Liquid Mediums
The atomic force microscope’s ability to measure conductive or non-conductive samples in air allows for characterization of complex polymers and biological samples. For samples that need to be kept hydrated or in a controlled liquid or pH solution, AFMWorkshop offers a fluid cell option that allows for AFM analysis in liquid.

Physical Properties of Nanoparticles
Many AFM modes may be used to measure nanoparticle physical properties such as magnetic fields, mechanical properties, electrical properties, and thermal conductivity.

Nanoparticle Size Analysis
A specialized AFMWorkshop optional Nanoparticle Analysis Software measures the critical dimensions of AFM nanoparticle images. This is possible because an AFM measures the entire three dimensional structure of the nanoparticles.

To learn more about AFM analysis of nanoparticles, feel free to visit http://www.afmworkshop.com.

Atomic Force Microscopes: An Ideal Tool For Instrument Innovators

The TT-2 AFM is ideal for instrument builders who want to use an Atomic Force Microscope as a platform for creating new instrumentation (such as a new imaging mode), or who want to use an Atomic Force Microscope in combination with another analytical instrument. TT-2 AFM customers have access to the systems software, mechanical drawings, and schematics. Because the software is written in LabVIEW, it can be easily modified to meet very specific demands.

TT-2 AFM software was developed in LabVIEW, making it easy for customers with a LabVIEW user license to customize their software. Additionally, National Instrument Data Acquisition Cards can be integrated into the TT-2 AFM to create a customized experiment.

Instrument Innovators are no longer faced with the decision to either create an entirely new AFM, or to live with the limitations of commercial AFMs that have limited documentation and a closed architecture. An engineering documentation package is available as an option to TT-2 AFM customers.

Mechanical Drawings

All the drawings for mechanical parts used to build a TT-2 AFM were created in AutoCAD and are included in the optional documentation package. If you require a .dwg file for a specific part in the TT-2 AFM, AFMWorkshop will provide it to you. Additionally, single parts in the microscope can be purchased if you need to modify a part for your needs. Each part is identified by part numbers on each mechanical drawing.

Software

National Instrument’s LabVIEW instrumentation programming language is setting the standard as the graphical programming environment for developing instrumentation. The TT-2 AFM includes a VI that can be modified for specific needs. The instrument control protocol for addressing functions such as Z feedback, XY scanning and stepper motor control is included with the technical documentation package. The AFMWorkshop does not provide a LabVIEW software development license – this must be purchased from NI.

Electronics

Direct access to TT-2 AFM electronics signals may be gained from a 50 pin ribbon cable at the rear of the TT-2 AFM EBox, or from the mode connector at the front of the microscope stage. For developers who want even more access, the technical guide includes schematics to all electronics in the TT-2 AFM, including: photodetector board, piezo electric control board, controller main board, and even the power supply board. There are several pinned signal access points on the main controller board.

To learn more about afmworkshop’s atomic force microscopes, feel free to visit www.afmworkshop.com.

AFMWorkshop – On-Site AFM Installation And Training

For those AFMWorkshop customers electing On-Site Installation & Training on their AFM, vs. the Assembly and Training program at the AFMWorkshop facility, AFMWorkshop has designed a set of procedures to facilitate optimal installation and function of your new AFM.

Once the new AFMWorkshop AFM is received at your facility, an authorized AFMWorkshop customer service engineer travels to your facility to install the AFM and to train your AFM users on the particular model’s operative techniques.

AFMWorkshop’s on-site training is designed for up to two designated operators of the AFM. These operators are then designated as the primary contact points between AFMWorkshop and the customer’s institution. During the installation and training visit, the focus is on training customers how to make optimal images of standard samples, not on specific applications. We find that this approach yields the best results for future success with the AFM. (If your facility’s AFM operators are interested in continuing their training on specific applications, AFMWorkshop offers five-day advanced applications workshops throughout the year.)

Day 1

The objective is to set up the AFM and ensure it is operating to factory specifications. The AFM’s proposed location is reviewed and remedies to any potential negative ambient impacts on the AFM’s performance are discussed.

Unpack AFM
Set up AFM
Evaluate AFM site for acoustic and structural vibrations
Verify system specifications

Day 2

The objective is to train up to two operators on the skills required to operate the AFM and to make images of standard samples. Skills reviewed include:

Changing samples
Changing probes
Aligning the light lever
Positioning the photo-detector
Selecting resonance (vibrating mode only)
Tip approach
Scanning
Optimizing GPID
High resolution scanning on the AFMWorkshop product

The final component to the AFMWorkshop On-Site Installation and Training is the preparation of a service installation report, completed and signed by both the installation engineer and the customer at the end of Day 2. This report verifies that the instrument is properly functioning and/or makes note of any problems that may need further attention. After the installation, follow-up questions should be primarily directed to the AFMWorkshop service engineer who performed the installation, and come through one of your facility’s two designated AFM users receiving the training.

AFMWorkshop covers all travel costs as well as room and board for the customer service engineer. We request a minimum of two weeks advance notice to schedule the installation.

To learn more about our AFM Installation Training programs, feel free to visit www.afmworkshop.com.

Nanoparticle Characterization With Atomic Force Microscopy

Two day course focusing on atomic force microscopy for nanoparticle characterization. Participants will learn an overview of AFM hardware and software, as well as imaging and data analysis techniques specific to nanoparticle characterization. Lab work mixed with coursework gives students hands-on experience using AFM to measure the properties of nanoparticles.

Atomic Force Microscopy to Characterize Nanoparticles

Two Day Training Course

The Atomic Force Microscope (AFM) allows for 3D characterization of nanoparticles with sub-nanometer resolution. Nanoparticle characterization using Atomic Force Microscopy has a number of advantages over dynamic light scattering, electron microscopy and optical characterization methods. The AFM provides powerful information on size, distribution, and geometries of nanoparticles.

Some of the unique advantages of nanoparticle characterization with an AFM include:

-Characterization of nanoparticles that are .5nm and up.
-Nanoparticle mixture distributions below 30 nm.
-Characterization of variable geometry nanoparticles.
-Direct visualization of hydrated nanoparticles/liquid medium.
-Characterization of nanoparticle physical properties such as magnetic fields.

This two day AFMWorkshop course mixes lecture with labwork on atomic force microscopy operation specifically as it applies to characterizing nanoparticles. AFM hardware and software will be reviewed, with special emphasis on the imaging modes and image processing needed to study nanoparticles. We will utilize AFMs from AFMWorkshop to teach basic concepts and demonstrate AFM operation, however attendees with experience on any make of AFM instrument will find the labwork relevant and practical.

Topics to Be Covered:

-Overview of AFM operation and different modes Topography measurements on nanoparticles.
-Nanoscale resolution
-Overview of AFM hardware
-Overview of AFM software
-Imaging modes for nanoparticles
-Imaging artifacts and best practices
-Image processing for important measurements on nanoparticles

Labwork:

-Scanning standard and reference samples.
-Nanoparticle imaging and image processing.
-AFM calibration

Interested in participating of our workshops?

To learn more about Atomic Force Microscopes Training, feel free to visit www.afmworkshop.com.

Magnetic Force Microscopy – Description, Specifications And More

This NanoLithography software option enables the AFM probe to alter the physical or chemical properties of the surface. Created in LabVIEW and integrated with the AFMControl software. VI’s are available to customers who want to modify the software and create new capabilities.

Description
Model: LITHO

This Lithography Software Option is used for nanolithography. That is, the AFM’s probe is used to alter the physical or chemical properties of the surface.

The software uses a script of commands to move the probe in a pre-determined pattern over a surface. The two commands are: “movement” and “hold”. During a movement and hold command, the voltage and force on the probe can be varied.A MOVEMENT command consists of 5 numbers (no letters) separated by commas:

They represent X, Y, Velocity, Setpoint%, and Z_DAC voltage
 X and Y are the coordinates in micron from the image plot.
 Velocity is the speed from one point to the next listed point in nm/sec.
 Setpoint% is the percent value of the existing setpoint.
 Z_DAC voltage is a voltage in the range of 0 to +5V which may be applied to the probe.

A HOLD command consists of 3 numbers (no letters) separated by commas:

They represent Setpoint%, Z_DAC voltage, and Delay Time (ms)

 Setpoint% is the percent value of the existing setpoint.
 Z_DAC voltage is a voltage in the range of 0 to +5V which may be applied to the probe.
 Delay time(ms) is the time in milliseconds that the probe is held in its present position.

A scripting file is a text file that may be created with any program capable of outputting a .txt file. Each motion of the probe required to create the pattern must be added to the .txt file. Complex patterns may be created using a large number of movement and hold commands.
As with all AFMWorkshop software products, this software option is created using VI’s in a LabVIEW™ environment and is integrated with the AFM Control software. The VI’s used to create the software are available to customers who want to modify the lithography software and create new capabilities.

Software

The lithography software window allows a user to load a scripting file. Once loaded, the pattern that will be made is displayed in an image window. When the start button is pressed, the script is implemented and the specifics of each step are listed in the window. A green light is displayed when the script is completed.

Included with the option

 PMMA sample
 Manual
 Plug for rear of unit
 Two probes:
 AppNANO: Doped Diamond (DD-ACTA-5)
 Conductive Diamond Tip – Non-contact mode probe
 Material: Si, N-Type, 0.01~0.025 Ohm/cm
 Cantilever: L= 125 μ, W=35 μ, T=4.5 μ
 Tip Radius: < 150nm, Height: 14-16 μ
 f: 200-400KHz, K=25~75 N/m

All atomic force microscopes manufactured by AFMWorkshop include standard scanning AFM modes: vibrating (tapping), non-vibrating (contact), phase scanning, and lateral force mode (LFM), and force distance. Optional modes expand the capability of your atomic force microscope. Besides Lithography, it includes: Conductive AFM, Magnetic Force Microscopy (MFM), and Advanced Force Distance modes. Measuring the conductivity, surface magnetic field, force curves, and manipulation of surfaces are possible with these modes.

AFMWorkshop instruments provide a high level of flexibility for conducting a wide array of tests and experiments, and always include vibrating, non-vibrating, phase and lateral force modes. Additional AFM modes and accessories expand the capabilities of your microscope.
Expand the range of your atomic force microscopy imaging by adding modes and accessories to your AFM.

To learn more about atomic force microscopes, feel free to visit http://www.afmworkshop.com.

An Overview Of AFM Workshop’s 15 Micron AFM Scanner

The 15 micron scanner is interchangeable with the 50 micron scanner in the TT-AFM. Extremely high resolution scans are made with the 15 micron scanner.

Description
Model: PS-2011

The PS-2010 and PS-2011 piezoelectric scanners are designed for use with the AFMWorkshop TT-AFM, and scan samples in the X, Y, and Z axis. Both products use temperature compensated strain gauges for linearizing scans in the X and Y axis. The PS-2010 has a temperature compensated strain gauge in the Z axis, while the PS-2011 does not. Both scanners use a modified tripod design for creating motion in the XY axis. Motion is generated through a lever arm. The lever arm in the 50 µm scanner is approximately 5:1 and in the 15 µm scanner it is 1:1. Animations on the AFMWorkshop website illustrate how the scanners operate. Each scanner contains a PC board with circuits for measuring ceramic motion with the strain gauge, as well as a 20 pin ribbon cable connector. The scanners are attached to the XY manual positioner with three M6 socket head screws.

Sample Holding Stage
Mounted on standard AFM metal disks, samples are held on an aluminum metal plate with two magnets. As shipped, the sample holder is electronically grounded to the microscope stage to help eliminate unwanted effects from sample charging. Included with each scanner is a leveling sample puck. The puck enables samples to be leveled, reducing the AFM image background bow to less than a few nanometers. The leveling sample puck is magnetically held to the sample stage, and has three set screws to level the puck relative to the XY scan axis.

Interchangeable
The 15 µm and the 50 µm scanners are interchangeable. The scanners are removed from the TT-AFM stage by simply unscrewing three M6 socket head screws and unplugging a 20 pin ribbon cable. It takes less than 5 minutes to remove one scanner and to replace it with the other scanner.

Want to expand the capabilities of your microscope?

You can add additional modes and accessories to achieve that. AFM accessories include focus assist and image loggers for AFMs, replacement scanners, probe holders, electronics, and stages, dunk and scan and environmental cell scanning options, and documentation packages for all AFMWorkshop products. Customers can purchase a standalone AFM stage and customize it to their needs using various scanners and light levers. Environmental cells and dunk and scan packages allow AFM scanning for samples submerged in liquids and inert gas.

To learn more about atomic force microscope, visit www.afmworkshop.com

Features of Table Top Atomic Force Microscope

This compact, second generation high resolution tabletop Atomic Force Microscope (AFM) has all the important features and benefits expected from a light lever AFM. The TT-2 AFM includes a stage, control electronics, probes, manuals, and a video microscope.

Key Features and Benefits of the TT-2 AFM

Low Noise Floor

With a noise floor <80 picometers, the TT-2 AFM is capable of measuring samples with features from nano-meters to microns.

Direct Drive Tip Approach

A linear motion stage moves the probe relative to the sample. The probe sample angle does not change, and samples of many thicknesses are readily scanned.

Research Grade Video Optical Microscope

With a mechanical 7:1 zoom and a resolution of 2 µm the video optical microscope facilitates locating features, tip approach, and laser alignment.

Multiple Scanners

Linearized piezoelectric scanners with several ranges are available to optimize scanning conditions.

LabView Software

The TT-2 uses industry standard lab view software. For customization, the systems VI’s are readily available.

Modular Design

Once you buy the TT-2 AFM you can add options and modes such as focus assist, image logger, lithography and liquid scanning when you are ready.

Simple Probe Exchange

With the removable probe holder, exchanging probes is simple, and takes less than a minute.

Light Lever Large Adjustment Range

Because the TT-2 has a large adjustment range on the laser and photodetector, probes from all major manufacturers can be used.

Applications

Research

With over 200 TT-2 AFMs in laboratories throughout the world, researchers have published 100s of publications in all types of science and engineering journals.

Instrument Innovators

The TT-2 AFM serves as an ideal platform for creating new and innovative instruments. AFMWorkshop facilitates instrument innovation with an open architecture.

Education

With its open design the TT-2 is ideal for colleges and universities that teach students about AFM design, applications, and operation.

The TT-2 AFM meets a wide variety of applications. More details on the use of the TT-2 AFM for educators, industry, and research can be found by clicking on www.afmworkshop.com or call at (888)671-5539 any queries.

Vibration Solution Products to Avoid Fuzzy AFM Images

AFMs are quite susceptible to external vibrations, structural vibartions are transmitted through a building structure and acoustic vibrations are transmitted through air. Both acoustic and structural vibrations degrade the resolution and overall performance of an Atomic Force Microscope.

External vibration can degrade the resolution of scans by adding extra noise. Atomic force microscope vibration solutions offer a way to reduce external vibration that often causes fuzzy AFM images. To reduce external vibrations and obtain the highest-quality AFM images, particularly for high-resolution scanning, AFMWorkshop has designed a variety of proven options for vibration isolation including vibration tables, vibration enclosures, bungee options, and even custom/OEM enclosures.

Vibration Isolation filters out unwanted acoustic structural vibrations that interfere with high-resolution scanning. Acoustic vibrations are reduced by placing the microscope in an acoustic isolation chamber. Structural vibrations are reduced by using a mechanical isolation platform.

Below are some vibration solution products offered by AFMWorkshop:
– Passive Vibration Table
Passive Vibration Table is a moderate Vibration solution when ultimate AFM Performance is not necessary.
– Active Vibration Table
An Active Vibration Table uses a feedback control method for removing vibrations for a better quality of scans.
– Acoustic Cabinet
An acoustic cabinet reduces unwanted vibrations transmitted through air.
– Custom OEM vibration enclosure
Customized (OEM) Vibration enclosure is a scalable vibration solution for any Atomic Force Microscopy System.
–Bungee Option
A Bungee Option is a relatively cost-effective method for reducing unwanted structural vibrations and improving the quality of AFM Image.

Looking for the best atomic force microscope vibration solutions? If yes, feel free to get in touch with AFMWorkshop or visit https://www.afmworkshop.com/.

LS-AFM for Life Science Applications

The LS- Atomic Force Microscope is designed specifically for life science applications when paired with an inverted optical microscope. This tip-scanning atomic force microscope includes everything required for AFM scanning: AFM stage, inverted optical microscope adaptation plate, EBox, manuals, cables, and AFM-Control Software.

Have a look at some of the features of LS-AFM:

A turnkey system with guaranteed results
No additional sample holding options required for most applications
Readily scan samples in ambient air and liquids
Zoom to feature with accurate positioning for F/D curves
Readily adaptable to new operating systems
Reduce time for probe exchange (& use any manufacturer’s probes)
Facilitates tip approach and laser alignment
Most common scanning modes included for life sciences applications

When an inverted optical microscope is required for locating cells or other bio-materials on a surface, the LS-AFM has a sample positoiner for glass slides and petri dishes. The LS-AFM can be purchased with the AFMWorkshop inverted optical microscope or it can be retrofitted to almost any inverted optical microscope.

LS-AFM APPLICATIONS

Measure the Stiffness of Biomaterials

LS-AFM can be used to monitor the deflection of a cantilever as it is pushed against sample resulting in a force/distance curve. From the force-distance curve, many parameters may be measured, such as stiffness of the sample and probe-sample adhesion.

Imaging Cells

Images of cells are easily scanned in both a liquid and dry environment with the LS-AFM. The inverted optical microscope facilitates direct placement of the probe on an area of interest for scanning.

The LS-AFM is a nanoscience instrument that‌ ‌may be purchased in two different configurations:

LS-AFM-A

In this configuration, AFMWorkshop fabricates a special plate that pairs the LS-AFM with the customer’s existing inverted optical microscope.

LS-AFM-B

This configuration of the LS-AFM includes a fully-featured inverted optical microscope.

Do you want to buy LS-AFMs? If yes, buy top quality LS-AFMs from AFMWorkshop. To learn more about the LS-AFM, feel free to visit https://www.afmworkshop.com.