ICSPI nGauge User manual

nGauge Atomic Force Microscope
User Manual Version 2.0
For Software and Firmware versions 1.0.0.0

© ICSPI Corp. 2007-2021 nGauge AFM User Manual 2.0 2
Table of Contents
1. Introduction..........................................................................................................................4
2. Safety and Precautions........................................................................................................4
3. Overview..............................................................................................................................7
3.1. AFM Basics...................................................................................................................7
3.2. MEMS AFM or AFM-on-a-Chip.....................................................................................7
3.3. nGauge AFM Components ...........................................................................................8
3.4. nGauge AFM Capabilities.............................................................................................8
4. Setup.................................................................................................................................10
4.1. Location......................................................................................................................10
4.2. Basic Set-up ...............................................................................................................11
4.3. Software Installation....................................................................................................12
5. Basic Operation .................................................................................................................13
5.1. Start-up.......................................................................................................................13
5.2. Chip Installation and Sample Placement.....................................................................14
5.3. Software Overview......................................................................................................17
5.4. Sweep.........................................................................................................................17
5.5. Approach ....................................................................................................................19
5.6. Scan ...........................................................................................................................23
5.7. Scanning Recommendations ......................................................................................29
5.8. Improving Performance...............................................................................................33
5.9. Advanced Scan Features............................................................................................36
6. Post-Processing.................................................................................................................38
6.1. Gwyddion....................................................................................................................39
6.2. Calibration...................................................................................................................40
7. Troubleshooting.................................................................................................................42
7.1. Set-up Troubleshooting...............................................................................................42
7.2. Sweep Troubleshooting ..............................................................................................44
7.3. Approach Troubleshooting..........................................................................................48
7.4. Scan Troubleshooting.................................................................................................52
8. Advanced Controls.............................................................................................................55
8.1. Sweep Advanced Controls..........................................................................................55
8.2. Approach Advanced Controls......................................................................................57

© ICSPI Corp. 2007-2021 nGauge AFM User Manual 2.0 3
8.3. Menu Button Advanced Controls.................................................................................58
9. Appendix............................................................................................................................61
9.1. Gwyddion Supplement................................................................................................61

© ICSPI Corp. 2007-2021 nGauge AFM User Manual 2.0 4
1.Introduction
Congratulations on purchasing an nGauge Atomic Force Microscope!
The nGauge AFM achieves magnification that far surpasses that of an optical microscope so
you can explore the world with nanometer-scale resolution.
The most up-to-date user manual can be downloaded from the ICSPI website at
https://www.icspicorp.com/resources
Please read the user manual before operating your new instrument to learn how it works, how to
set up and operate the hardware and software, how to prepare samples, and how to visualize
your data.
2.Safety and Precautions
The following warnings and precautions should be observed to ensure the safety of the user
and the instrument:
•Use only the power supply provided. The driving electronics are designed to accept
7.5 V (DC) and an internal fuse prevents the input current from exceeding 1 A.
•The stage contains moving parts that could pinch. To avoid minor injury, be aware of
the moving parts.
•Do not disassemble the system. Except for sample platform customization,
disassembly of the system voids the warranty and could result in damage to the
electronics or the mechanical components.
•Be extremely careful when handling an AFM chip. They are very fragile and will
break if the tip is touched. AFM chips should be stored in their box with the tip facing
DOWN and removed using the tweezers provided. If necessary, the AFM chip can be
placed on a flat surface with the tip facing up. The AFM chip can be picked up by hand
by the board as long as you are careful to avoid touching the tip.
The tip, located at the edge of the
board, is extremely fragile.

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AFM chips should be stored with the
tip facing down in the storage box.
Use tweezers to pick them up.
The AFM chip can be placed on a
flat surface with the tip facing up.
The AFM chip can be picked up by
hand as long as you don't touch the
tip.
This is a zoomed-in photo of the
AFM chip. The chip is extremely
fragile.

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Sample should not move during scanning
Make sure that the sample is stable and will
not move during scanning.
Lightweight samples should be mounted
onto a rigid substrate like a glass slide or
metal disc.
Keep the chip a safe distance from the sample
When installing or removing a chip, make
sure that there is at least 5 mm of space
between the tip and the sample.
To retract the tip in the software, go to the
Approach page and click and hold the
Retract button.
Probe tip is susceptible to damage when engaged
Do not touch the sample, chip or unit when
the tip is approaching or in contact with the
sample. The probe tip is susceptible to
damage when approaching or engaged.
Minimize contact between tip and sample
Minimize the amount of time that the tip is
contact with the sample. When you are
finished scanning, navigate to the Approach
page:
1. Click on Disengage.
2. Wait for the button to indicate Retract.
3. Click and hold on Retract until the tip is
at least 5 mm away from the sample (about
10 seconds).
1
2
DISENGAGE
RETRACT

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3. Overview
3.1. AFM Basics
Unlike optical microscopes that use light and lenses to magnify, or electron microscopes which
use electron beams to generate an image, an atomic force microscope (AFM) uses a very sharp
tip to scan across the surface of a sample. AFM measures tip-sample interaction forces and
generates a 3D reconstruction of a sample surface.
This scan moves in X and in Y. It moves quickly from left to right (in the X direction, also known
as the fast scan axis), then moves backwards (reverses), and moves down to the next row (Y
direction) in the slow scan axis. The pattern is known as a raster scan.
A controller maintains a constant tip-sample force by adjusting the tip's Z height. The control
effort then represents the height of the features on the sample.
Conventional AFMs typically use a probe with a sharp tip on a silicon cantilever. A laser beam is
reflected off the backside of the cantilever onto a photodetector that measures any small
displacements of the cantilever. A piezoelectric Z-scanner controls the height of the probe while
a piezoelectric XY stage raster scans the sample in X and Y.
3.2. MEMS AFM or AFM-on-a-Chip
MEMS AFM or AFM-on-a-chip operates almost exactly like a conventional AFM except that all
of the essential components are integrated onto a single chip. The nGauge AFM chip is a micro
-electro-mechanical systems (MEMS) device that uses the most advanced manufacturing
process in the world to produce tiny, ultra-precise scanners and sensors on a 1 mm x 1 mm
silicon chip.
An AFM on a chip has a cantilever and a sharp tip but instead of a laser it has an integrated
piezoresistive strain sensor to measure tip displacements. The tip and sensor are attached to a
MEMS scanner that can position them in X, Y, and Z with sub-nanometer resolution.

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3.3. nGauge AFM Components
The nGauge AFM system includes all of the following components. A computer (not included)
with a USB port is required and access to a power outlet.
1. Stage
2. Sample Platform
3. Thumb Nut
4. AFM Chips
5. Power Supply
6. USB Cable
7. Tweezers
3.3.1. Detachable Sample Platform
nGauge AFM models 1.1 and 1.2 feature a detachable sample platform. These screws are
removable, and the stage can be customized.
3.3.2. Hole in base plate
The base plate features a hole for mounting the nGauge AFM onto an optical table.
3.4. nGauge AFM Capabilities
3.4.1. Scan Mode
The nGauge AFM operates in tapping mode (also known as intermittent contact or dynamic
mode): the cantilever oscillates at its resonant frequency and makes intermittent contact or
“taps” the sample surface.
The nGauge AFM uses the amplitude of oscillation as the feedback mechanism, also known as
amplitude-modulation AFM (AM-AFM) mode.
The nGauge generates topography, phase and error images simultaneously.

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3.4.2. Scan Operation Environment
The nGauge AFM is designed to operate in ambient environment (normal room temperature
and pressure).
3.4.3. Scan Size
The nGauge AFM can scan areas of up to 20 µm x 20 µm in X and Y, up to 60 µm in X and
vertical distances up to 10 µm in Z (peak-to-valley) with <1 nm RMS noise in the vertical
direction.
3.4.4. Sample Types
Any solid sample can be imaged, including both conductive and non-conductive, but the
nGauge AFM cannot operate in liquid and cannot image liquid samples.
Some samples that are prone to surface charging, such as highly electrically resistive polymers,
may require a way to mitigate surface charging.
The maximum sample size for the normal sample platform is 100 mm × 50 mm × 16 mm
L×W×H.
The maximum sample weight is 1 kg.

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4.Setup
4.1. Location
The nGauge AFM is small, simple, and portable, and can be set up virtually anywhere. For best
results, it is recommended that you follow these guidelines:
Normal
temperature
and pressure
The nGauge system should be set up in areas with normal room
temperature and pressure.
Flat surface
The nGauge system should be set up on a flat, level surface, like a desk or
tabletop, with enough space to ensure that the stage does not get bumped
or moved while imaging.
Vibrations
The unique design of the nGauge AFM minimizes the effects of common
sources of low-frequency vibrations, such as those caused by people
walking by, doors opening and closing, and building vibrations. However, it is
best to set the system up on a solid, stable surface away from as many
sources of vibration as possible. The corner of a room is a good choice.
Air drafts
The system is not immune to air drafts and should be set up away from air
vents, drafty windows, etc. If possible, set up the nGauge AFM in the corner
of a room or near a wall where there is less air flow. If air drafts are
unavoidable and present a significant problem, a box or enclosure around
the system may be required.
Electrical
noise
The system meets the FCC guidelines for electrical interference, but it is
best to avoid setting it up near sources of electrical noise, such as server
rooms or rooms operating high-power equipment.

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4.2. Basic Set-up
Follow these steps to set up your nGauge AFM system:
1. Remove the components from the carrying case. Set the stage upright on a flat surface.
2. Plug the power supply into a wall outlet and into the power connector in the stage.

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3. Connect the USB cable to a computer and to the USB connector in the stage.
4.3. Software Installation
The software required to operate the nGauge AFM can be found on the USB key provided or
downloaded from https://www.icspicorp.com/resources
To install the software, run the executable installer “nGauge_setup_x.x.x.x_windows.exe”.
4.3.1. Automatic Updates
If a network (internet) connection is available, the software will automatically check for software
updates from the ICSPI server. This information is displayed on both the home screen and in
the updates section of the menu. To manually query the ICSPI update server for new updates,
click Check Updates under the updates section of the menu.

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4.3.2. Gwyddion
The free, open-source AFM post-processing software called Gwyddion is a very useful tool and
should also be installed. You can download it from the Gwyddion website:
http://gwyddion.net/download.php
See Section 6.1 for more details on how to use Gwyddion.
5.Basic Operation
5.1. Start-up
Launch the software by double-clicking on the nGauge program on your desktop or searching
for nGauge in the start menu. If the AFM is powered up and connected to the computer with the
USB cable, the welcome screen should display the message "AFM Ready". If not, refer to
Section 7.1 Set-up Troubleshooting.
Click the Enter button to proceed.

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5.2. Chip Installation and Sample Placement
Once the AFM has been set up and the software installed, you are ready to install a chip.
1. Completely unscrew and remove the thumb nut from the stage.
2. Open the AFM chip box and pick up an AFM chip using the tweezers.

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3. Carefully place the AFM chip onto the alignment pins on the stage with the tip facing
down.
Important: During this step, the sample platform should be retracted sufficiently to avoid
any contact between the tip and platform. If the sample platform is 10 mm away, it is
recommended to go to the Approach page in the software and click and hold on the
Retract button until the sample platform is separated by 15 mm or more from the chip
installation area.
4. Replace the thumb nut and firmly tighten it.

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5. Place your sample on the sample platform, ensuring that there is no contact with the tip.
If the sample will not fit under the tip, lower the sample platform by clicking on the
Approach tab, then clicking and holding down the Retract button until the platform is
low enough. Position the sample so that the area to be scanned is directly under the tip.
You can also remove the chip before placing the sample and re-install the chip.
IMPORTANT
Ensure the sample is stable on the sample platform, and that it will not move while scanning.
If you have a lightweight sample, ensure that it is firmly affixed to a rigid substrate such as a
glass slide or AFM sample disc.

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5.3. Software Overview
The nGauge AFM software is divided into three pages: (1) Sweep, (2) Approach, and (3) Scan.
To navigate between the three pages, click on the desired tab at the top of the page.
There is a dropdown menu called ‘Show Advanced Controls’ on each page that displays
advanced controls specific to that page.
The menu button at top-right of the page displays a detailed Advanced Setting menu for
advanced aspects of AFM configuration. The settings in this menu are not required for normal
operation and only advanced users should use these controls. More details are available in
Section 8.3 Menu Button Advanced Controls.
5.4. Sweep
Click the Sweep button to perform a frequency sweep of the cantilever. The frequency sweep
determines the resonant frequency of the cantilever and takes a few seconds to complete.
Whenever a chip is installed, a frequency sweep must be performed. Each chip will have a
slightly different resonant frequency.
5.4.1. Cantilever Drive Amplitude
When the frequency sweep is complete, two graphs will be displayed: an amplitude graph and a
phase graph. The amplitude graph should display a smooth curve with a peak greater than 2 V,
but less than 3.3 V.

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In the screenshot below, the peak of the amplitude curve is about 2.5 V.
If there is a peak, but it is above 3.3 V or below 2 V, click on Show Advanced Controls and
adjust the Cantilever Drive Amplitude. The default value is 35%. Adjust the value and click on
Sweep again. Continue adjusting the value and clicking on sweep until the peak is between 2
and 3.3 V.
Once you are satisfied with the frequency sweep, click on the Approach tab.
If your sweep is noisy (not smooth) or you encounter an error, refer to Section 7.2 Sweep
Troubleshooting.
5.4.2. Resistance Check
When the Sweep button is clicked, the resistances of the MEMS scanners of the AFM chip are
checked. There are five scanners on the AFM chip: X1, X2, Y1, Y2 and Z.
A high or low resistance value indicates that there may be a problem with the actuator, such as
poor electrical contact (thumb nut is not tight enough or dust is interfering) or a physically
damaged scanner.
An error message stating “Broken device or no device detected” will be displayed if a high or
low resistance value is detected. If you observe this error, try tightening the thumb nut and
clicking on Sweep again. If you continue to encounter the error, refer to 7.2.1 Broken device or
device not found error for more information.
5.4.3. Advanced Controls
Refer to Section 8.1 Sweep Advanced Controls for more information on advanced controls for
the Sweep page.

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5.5. Approach
The Approach page is where you can start an approach of the sample to the tip. There are two
controls: “Approach” and “Retract”. Clicking on the Approach button initiates an automatic
approach. Clicking and holding on Retract will move the sample platform downwards.
The Approach page also has an indicator for the Motor status and the Approach status.
Ensure that the target area of your sample is below the nGauge AFM tip. Click the Approach
button to initiate the automatic approach of the sample to the probe tip. The sample platform will
rise quickly and then slow down for a final approach once the sample gets very close. When the
tip engages with the sample, the Approach status will change from “sample not in contact” to
“approach complete”.
To stop the approach before it is complete, click on Pause. You can retract the sample platform
by clicking and holding on Retract.

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When you are done scanning or do not want to scan, click on Disengage to disengage the tip.
The disengage routine will take a few seconds and the Approach status will change to ‘sample
not in contact’ and the Amplitude will increase:
You can safely click and hold on the Retract button to move the sample platform downward
away from the tip.
Important: Always disengage the tip and retract the sample away from the tip when the
nGauge is not in use.
Important: If the tip is engaged with the sample and the tip is not on the target area, you must
click on Disengage and then click and hold on Retract to move the sample platform away from
the tip before re-positioning the sample.
5.5.1. Amplitude Graph
There are two graphs on the Approach page. The first graph represents the cantilever oscillation
amplitude, and the second graph represents the Fine Z value, which represents the tip height.
When the tip is far away from the sample and oscillating in free air, it will have an oscillation
amplitude that is the same as it was set on the Sweep page.
The setpoint is the dotted line in the middle of graph. By default, the setpoint is set to half of the
free air oscillation amplitude.