Name: Quantitative Hardness Measurement by Instrumented AFM-indentation (Video) | JoVE Journal
Uploaded: 2016-11-22T14:00:00.000+00:00
Duration: 8 min 21 s
Description: Learn quantitative nano hardness measurement of gold thin films using instrumented AFM indentation. This technique reveals material strengths and plastic deformation mechanisms at the nanometer scale for nanomechanics research.

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5 minutes

A.C. is grateful to KoreaTech for financial support.

1. Instrumental Set-up and Calibration

<ol>
	<li>Instrumental set-up
	<ol>
		<li>Use a stiff diamond-coated cantilever of the type DT-NCLR or CDT-NCLR with a first free resonance frequency f0,1 ≥ 180 kHz, a quality factor Q ≥ 300, and a bending stiffness k ≥ 40 N/m.</li>
		<li>Mount the selected cantilever onto a clamping holder provided by the AFM manufacturer. Take special care to place the cantilever such that its long axis is perpendicular to the fast scan direction of the AFM. Alternatively, glue the cantilever onto a cantilever holder provided by the AFM manufacturer using dual-component epoxy glue.</li>
		<li>Mount the cantilever holder onto the AFM head and use the optical microscope normally available with the AFM system to focus on the AFM cantilever. Double check that the cantilever's long axis is perpendicular to the fast scan direction. If not, go back to Section 1.1.2.</li>
		<li>Align the laser beam so that it is reflected at the end of the cantilever. Monitor the voltage sum at the photodiode and conduct a fine adjustment to maximize the sum signal. Typical sum signal values are in the range of 2 V.</li>
		<li>Adjust the mirror's horizontal and vertical tilt angles so as to bring the reflected laser spot into the center of the photodiode, where the voltages corresponding to the vertical and lateral displacement are nearly zero.</li>
	</ol>
	</li>
	<li>Calibration
	<ol>
		<li>Perform a frequency sweep to determine the first free bending resonance f0,1 of the cantilever.</li>
		<li>Determine the bending stiffness of the cantilever k, calculated according to19 
		(1)  <img alt="Static equilibrium formula, k=Ewt³/4L³; bending stiffness equation, structural analysis." src="/files/ftp_upload/54706/54706eq1.jpg" data-altupdatedat="1788235205000" data-alt="Equation 1"> 
		where E is the Young's modulus, L is the length of the cantilever, w is the width of the cantilever, and t is its thickness. To this end, measure the length and width of the cantilever by optical microscopy or scanning electron microscopy for better accuracy. Calculate the thickness of the cantilever from its first free bending resonance frequency f0,1, according to 
		(2) <img alt="Equation for resonance frequency calculation in dynamic analysis setup." src="/files/ftp_upload/54706/54706eq2.jpg" data-altupdatedat="1788235205000" data-alt="Equation 2"> 
		where ρ is the mass density.</li>
		<li>Select the default value of the photodiode sensitivity for the particular cantilever type to be used for the experiment in the set up menu of the AFM. Bring the cantilever tip into contact with the reference sample at a load Fn = 10 nN by clicking the approach button.</li>
		<li>Open the force spectroscopy menu in the AFM software and set the relative retraction and extension of the z-scanner to 50 nm and the z-scanner retraction/extension to 0.3 µm/sec. Doing so, the recording of the force-distance curve will consist first of a retraction of the z-scanner to 50 nm away from the sample surface and then of a series of approaches and retractions of the same distance.</li>
		<li>Record a force distance curve with the set parameters suggested in 1.2.4 on a smooth and non-compliant surface, such as nano-crystalline diamond or sapphire, in order to avoid sample deformation effects. To do so click on the acquire button in the force spectroscopy menu of the AFM software.</li>
		<li>Fit the repulsive part of the force-distance curve with a linear function, in the calibration menu of the AFM software. The inverse slope of the fitting line corresponds to the photodiode sensitivity S. Substitute the determined value to the default value of the instrument software in the calibration menu of the AFM software by clicking the execute calibration button.</li>
	</ol>
	</li>
</ol>
2. Sample Preparation
NOTE: The sample measured in this experiment consists of a 100-nm-thick, atomically smooth Au(111) thin film grown on mica by physical vapor deposition.
<ol>
	<li>Mount the sample onto a magnetic sample holder provided by the instrument manufacturer by means of double-sided carbon tape. In order to avoid drift of the sample during measurements, mount the sample one day before the measurements, so as to let the carbon tape relax. Alternatively, mount the sample onto the holder with silver paint, which usually dries within a few minutes.</li>
	<li>Mount the magnetic sample holder onto the x/y scanner.</li>
</ol>
3. Measurement Procedure
<ol>
	<li>Set the oscillation frequency slightly off-resonance (in this experiment f = 190.67 kHz) and the oscillation amplitude at A = 20 nm Note that these values are automatically set by the instrument software for this particular cantilever. Set the oscillation set point manually at Aset-point = 5 nm.</li>
	<li>Draw the cantilever toward the sample surface using the step-motor of the AFM. Make sure that the force sensor does not collide with the sample surface. Keep the cantilever in focus during coarse approach and stop the coarse approach before the sample surface is in perfect focus.</li>
	<li>Automatically approach the force sensor by clicking on the approach button. Once the oscillation amplitude has reached its set point, the tip is ready to scan the topography of the sample surface.</li>
	<li>Record a series of topography images on areas ranging from 5 x 5 to 1 x 1 µm² (if available, adjust the slope of the topography signal by tilting the x/y-scanner). Make sure that successive images of the same area do not exhibit any sign of drift and that the z-scanner position remains almost constant. If this is not the case, continue imaging until the system has stabilized.</li>
	<li>Once the system has stabilized and a smooth 1 x 1 µm² area has been found, retract the force sensor a few micrometers from the sample surface by clicking on the retract button.</li>
	<li>Select the force spectroscopy mode in the instrument menu and move the force sensor to the middle of the preselected 1 x 1 µm² area, with a force set-point of 10 nm. Monitor the position of the z-scanner until it remains constant.</li>
	<li>Select the 2 x 2 grid of points whose center corresponds to the center of the preselected 1 x 1 µm² area. Set the distance between two next neighboring points at 500 nm.</li>
	<li>Set the relative scanner distance to vary from 0 to 150 nm at a speed of 300 nm/sec and to then retract over the same distance and at the same velocity. Given the tilt angle of the cantilever with regard to the sample surface, apply a tilt correction by moving the lateral scanner by Z × tanφ during a vertical scanner extension Z, where φ is the tilt angle20. 
	NOTE: A few instruments account for the cantilever tilt in their force spectroscopy or indentation mode; this is the case for the AFM used in this work.</li>
	<li>Press the start button in the instrument software to begin the acquisition of the AFM indentation data.</li>
	<li>Once the AFM indentation measurements have been completed, retract the force sensor a few micrometers away from the sample surface.</li>
	<li>Select the non-contact AFM mode imaging in the instrument software menu and repeat the procedure described in Sections 3.1 and 3.2.</li>
	<li>Perform a scan over the same 1 x 1 µm² surface area as in Section 3.3 so as to locate the exact position of the indents. Further surface scans over a 500 x 500 nm² surface area can be performed to image the remaining indents with greater detail.</li>
</ol>
4. Data Analysis
<ol>
	<li>Image processing
	<ol>
		<li>Process the recorded topography images so as to align the lines in the fast scan direction based on median difference. Use the built-in function of Gwyddion.</li>
	</ol>
	</li>
	<li>Calculate the projected area Ap of indents using the indentation analysis function of Gwyddion.</li>
	<li>Estimate the AFM tip shape from the topography images of indents by using the tip analysis function of Gwyddion. Then average the tip shape images and measure the half-opening angle α of the averaged tip shape.</li>
	<li>Convert the force-distance curves into force-displacement curves by calculating the tip displacement δ according to13 
	(3) <img alt="Static equilibrium formula δ=Z−(Fn/Cn), mathematical equation." src="/files/ftp_upload/54706/54706eq3.jpg" data-altupdatedat="1788235205000" data-alt="Equation 3"> 
	where Z is the relative scanner position.</li>
	<li>Now, plot the force versus the tip displacement. The resulting curve usually displays so-called pop-ins, with lengths in the range of several 100 pm, that correspond to atomistic plasticity events. Use the first of these pop-ins to determine the tip displacement at the elastic limit δel4.</li>
	<li>Fit the elastic part of the force-displacement curve with the Hertzian function21. 
	(4)  <img alt="Static equilibrium equation, P = \( \frac{4}{3} \sqrt{RE*} \delta^{3/2} \); formula analysis." src="/files/ftp_upload/54706/54706eq4.jpg" data-altupdatedat="1788235205000" data-alt="Equation 4"> 
	where R is the tip radius and E'* is the reduced modulus of elasticity, given by  <img alt="Elastic modulus equation, formula for composite materials stiffness, mathematical representation." src="/files/ftp_upload/54706/54706eq5.jpg" data-altupdatedat="1788235205000" data-alt="Equation 5">, with Ms,t being the indentation modulus of the sample and of the tip, respectively. In this case, the fit parameter is <img alt="Mathematical expression, 4/3 root RE*, fluid dynamics calculation, formula on white background." src="/files/ftp_upload/54706/54706eq6.jpg" data-altupdatedat="1788235205000" data-alt="Equation 6">.</li>
	<li>Extend the fit function into the plasticity regime so as to calculate the work of plasticity Wplasticity from the areal difference between the fit function and the experimental curve21.</li>
	<li>Calculate the hardness of the sample according to1, 2 
	(5) <img alt="Atomic force microscopy equation, \(H_{AFM}=F_{n,max}/A_p\), used for surface hardness analysis." src="/files/ftp_upload/54706/54706eq7.jpg" data-altupdatedat="1788235205000" data-alt="Equation 7"> 
	and 
	(6) <img alt="AFM indentation formula diagram; static equilibrium; force analysis; nanomechanics calculation." src="/files/ftp_upload/54706/54706eq8.jpg" data-altupdatedat="1788235205000" data-alt="Equation 8"> 
	where Fn,max is the maximal applied load, Ap is the projected area of the indent calculated in Section 4.2, α is the half-opening angle of the tip calculated in Section 4.3, δel is the tip displacement at the first plasticity event, and δmax is the maximal tip displacement (See Section 4.4).</li>
</ol>

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</ol>

The authors have nothing to disclose.

A method has been presented for performing a series of indentations on an Au(111) thin-film surface with a diamond-coated AFM tip. Non-contact AFM imaging and AFM indentation were performed with the same force sensor. The requirements for non-contact imaging are a high first free resonance frequency f0,1 &#8805; 180 kHz and a high quality factor Q &#8805; 300. In AFM indentation, the vertical force to be applied is in the range of several micro-newtons, and a cantilever with a high bending st...

For the last 150 years, hardness values have been used to characterize the mechanical behavior of materials and to predict their performance under various loading conditions. The hardness of a material describes the resistance of its surface to the penetration of a harder indenter. For metallic materials, the hardness relates to resistance to plastic flow.
Although the implementation of hardness testing has proven to be relatively easy, the yielded results have long been rather empirical, making them unable to describe the intrinsic properties of the investigated material. The empirical nature of hardness testing results has been a consequence of the use of various indenter geometries, each of which has a different established hardness scale. However, all empirical hardness scales, such as the Brinell hardness (HB) test for spherical indenters and the Vickers (HV) and Knoop (HK) hardness tests for different types of four-sided pyramids, have one thing in common: the hardness number is determined from the ratio of the applied load to the developed area of the remaining indent. In an attempt to relate the hardness of metals to their fundamental mechanical properties, the hardness measured with a spherical indenter has been defined as the ratio of the applied load to the projected area of the remaining indent. This hardness value, also known as the Meyer's hardness (H), is equal to the mean contact pressure and directly relates to the yield strength of non-work-hardening metals1. 
Hardness testing has long been limited to the macro-scale, in which case the sizes of indents have been measured by optical means. The development of instrumented indentation, where force-displacement curves are recorded, has been recognized as a valuable alternative for determining the hardness of a material, although the size of the remaining indent may be too small to be accurately imaged. In this case, the projected area of the indent is calculated from the tip displacement according to a so-called indenter-area function2. Due to this development, the analysis of the curvature of force-displacement curves and of the occurrence of distinct plasticity events in the shape of pop-ins is now widely used to study the mechanisms of plastic deformation at the micrometer scale, such as by means of nanoindentation3.
It is well accepted that the carriers of plastic deformation in metals, i.e., dislocations, operate at the nanometer scale. To understand their modes of operation at the atomic level, new experimental techniques with atomic resolution are needed. Initial investigations of atomistic plasticity events at the interfaces between nanometer-sized single asperities and single crystalline Au surfaces of different orientations have been carried out by interfacial force microscopy (IFM)4, 5. Atomic force microscopy (AFM) indentation has been applied to observe the nucleation and gliding of single dislocations in KBr(100) single crystals6, Cu(100)7, and Au(111)8, 9. There, atomistic plasticity events were observed in the shape of pop-ins, with lengths in the range of 1 &#197;. AFM indentation has also been used to measure the nano-hardness and -elasticity of gold nano-island grown on mica10. In this work, the nano-hardness was found to be smaller than the bulk value and was observed to depend linearly on the indentation area. Also, a detailed measurement protocol has been proposed to determine the hardness of hard surfaces, such as fused quartz and silicon, by AFM indentation with a diamond-tipped sapphire cantilever11. In particular, this method takes into account the non-linearity of the photo-sensitive deflection detectors for large cantilever deflection12. More recently, AFM indentation and non-contact AFM imaging have been combined to quantitatively determine the hardness and the fundamental mechanisms of plastic deformation of a Pt(111) single crystalline surface and Pt-based metallic glass13. For Pt(111), plastic deformation mechanisms at the nanometer scale were found to be consistent with the discrete mechanisms established for larger scales. Further, the nanometer-scale plastic deformation of the metallic glass was found to be not discrete, but rather continuous and highly localized around the indenting tip. These results revealed a lower size limit for metallic glasses, below which shear transformation mechanisms are not activated by indentation. AFM indentation has also been used to determine the hardness values of biological samples (such as collagen fibrils)14, polymers15, and colloidal crystals16.
In the present work, a careful experimental procedure is described that includes the force sensor selection, its calibration, the calibration of the cantilever deflection detection system, and the minimization of instrumental drift for accurate and reproducible force-distance measurements. Also, a method for the data analysis is presented that allows the extraction of force-penetration curves from recorded force-distance curves. Further representative results are shown and discussed in the light of recent findings in the field of plastic deformation of small volumes.
For this experiment, an atomic force microscope (AFM) was used. The cornerstone of an AFM is its micro-fabricated force sensor (usually a cantilever beam), with a sharp tip at the end whose radius is in the range of several nanometers. In the particular configuration of the instrument used for this experiment, the cantilever is mounted onto a piezo-electric z-scanner, while the sample to be investigated is mounted onto a piezo-electric x/y-scanner. During AFM imaging, the force sensor tip is scanned over a sample to register interaction forces with the sample surface that result in a deflection of the cantilever according to Hooke's law. The static or dynamic deflection of the cantilever can be measured with an optical beam deflection detector, consisting of a laser diode, a set of mirrors, and a photodiode that converts the cantilever deflection into a voltage. During imaging, the signal at the photodiode is controlled by a feedback loop so as to keep the interaction forces at the sample surface; this results in adjustments of the z-scanner position, which are recorded and displayed as a topography image.
Prerequisites for the experiment described below are that the piezo-electric scanners of the atomic force microscope are well-calibrated and that the instrument stays in the laboratory at a constant temperature and humidity level. The reader should be aware that, depending on the atomic force microscope model, some of the experimental procedure steps may have to be modified. In particular, all measurements are performed after setting the scanners' ranges to "small"; this function allows for the reduction of the x/y-scanner range to 5 x 5 &#181;m&#178; and the z-scanner range to 4 &#181;m, which ensures a resolution at small scales. This function is not available on all commercial AFM and is not mentioned in the remainder of the text.
For data analysis, the use of the free SPM data analysis software Gwyddion17 and the Matlab software package18 are recommended.
This protocol gives a description of the experimental procedure to be followed in order to perform instrumented hardness measurements by AFM. Since the handling of different commercial AFMs may differ from one model to the other, the reader should refer to the manual provided by the AFM manufacturer for detailed setting procedures and software information. In the following text, in order to reproduce the described experiment, it is assumed that the reader is familiar with the handling of the particular AFM used here.

<table><tbody><tr><td>AFM XE-100</td><td>Park Instruments</td><td>discontinued</td><td>Atomic force microscope</td></tr><tr><td>CDT-NCLR</td><td>NanoSensors</td><td>CDT-NCLR</td><td>Conductive diamond coated non-contact lever</td></tr><tr><td>100 nm thick Au(111) thin film on Mica</td><td>Phasis</td><td>20020011</td><td>atomically smooth gold thin film</td></tr></tbody></table>

quantitative hardness measurement by instrumented afm-indentation

Quantitative Hardness Measurement by Instrumented AFM-indentation

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness measurements on an Au(111) surface with atomistic resolution of single plasticity events. A careful experimental procedure is described that includes the force sensor selection, its calibration, the calibration of the cantilever deflection detection system, and the minimization of instrumental drift for accurate and reproducible force-distance measurements. Also, a method for the data analysis is presented that allows the extraction of force-penetration curves from recorded force-distance curves. A typical curve displays a clear elastic deformation regime up to the first plasticity event, or pop-in, with a length in the range of one to two Burger's vectors. Later plasticity events exhibit the same magnitude. The work of plasticity is further extracted from the measurements. Finally, the hardness is determined in combination with the indentation curve using non-contact atomic force microscopy images of the remaining indents.

In this work, the bending stiffness of the cantilever k was calculated according to the geometrical beam theory19. For the particular diamond-coated cantilever used in this work, we found k = 55.69 N/m. Note that we neglected the diamond coating; the thickness of the diamond coating is one to two orders of magnitude smaller than the cantilever thickness and thus does not significantly increase its bending stiffness (although its Young's modulus is significantl...

This experimental protocol describes how atomic force microscopy can be used to measure hardness at the true nanometer scale and to detect single atomistic plasticity events.

In this work, a combination of amplitude-modulated non-contact atomic force microscopy and atomic force spectroscopy is applied for instrumented hardness ...

The overall goal of this AFM based experiment is to quantitatively determine the nano hardness of gold thin film. This method can help on the key question in the nano mechanics of materials field regarding the strengths of materials at the nanometer scale and help to determine the mechanisms responsible for plasting deformation The advantage of this technique, how it's high special and forced resolutions. To begin, mount a stiff diamond coated cantilever with the first free resonance frequency of at least 180kHz, a quality factor of at least 300 and a bending stiffness of at least 40 N/m onto a clamping holder of the AFM.Mount the cantilever holder onto the AFM head align the laser beam and perform a frequency sweep to determine the first free bending residence of the cantilever. Then, in the set up menu of the AFM software, select the default value of the photodiode sensitivity for the particular cantilever type. Place a smooth and non-compliant surface such as nano crystal and diamond or sapphire into the sample holder.Next, draw the cantilever towards the reference sample surface, using the step motor of the AFM. Keep the cantilever in focus during course approach and stop the course approach before the sample surface is in perfect focus in order to avoid contacting the surface. Next, click the approach button to bring the cantilever tip into contact with the reference sample at a load of 10 nano newtons.In the force spectroscopy menu, set the relative retraction and extension of the z scanner to 50 N/m and the z scanner retraction and extension to 0.3 micrometers per second. Click on the acquire button in the forced spectroscopy menu to record a forced distance curve on the non compliant surface. In the calibration menu of the software, fit the repulsive part of the forced distance curve with the linear function, then substitute the determined value with the default value by clicking the execute calibration button.Mount the sample onto a magnetic sample holder and place the holder onto a scanner. Prior to measuring the sample, set the oscillation frequency slightly off resonance at 200.26 khz and the oscillation amplitude to 23.35 nm. Then, enter an oscillation set point of 5 nanometers.Next, draw the cantilever towards the sample surface using the step motor of the AFM. Keep the cantilever in focus during course approach and stop the course approach before the sample surface is in perfect focus in order to avoid contacting the surface. Now, click on the approach button to automatically approach the foresensor.Once the oscillation amplitude has reached its set point the tip is ready to scan the typography of the sample surface. Record a series of typography images on areas ranging from 5 micrometers by 5 micrometers to one micrometer by one micrometer. As needed, adjust the slope of the typography signal by tilting the xy scanner.Make sure that successive images of the same area do not exhibit any sign of drift and that the z scanner position remains almost constant. While attempting this procedure it is important to remember to minimize the instrumental drift. To do so, successive imaging of an area to be indented can be performed prior to the measurements.Once the system has stabilized in the smooth one micrometer square area has been found, click on the retract button to back the fore sensor a few micrometers from the sample surface. Then, select the fore spectroscopy mode, set the fore set point to 10 nanometers and move the fore sensor to the middle of the pre-selected one micrometer square area. Monitor the position of the z scanner until it remains constant.Select a two by two grid of points whose center corresponds to the center of the pre-selected area and set the distance between the two next neighboring points at 500 nanometers. Also, set the relative scanner distance to go from 0 to 150 nanometers at a speed of 300 nanometers per second and then to retract over the same distance and at the same velocity. Apply a tilt correction as described elsewhere by moving the lateral scanner by z times tangent pi during a vertical scanner extension of length z where pi is the tilt angle.At this point, press the start button to begin the acquisition of the AFM indentation data. Once the AFM indentation measurements have been completed, retract the fore sensor a few micrometers away from the sample surface. Then, perform a scan over the same 1 micrometer square surface area so as to locate the exact position of the indents.Perform additional scans over a 500 by 500 nanometers square surface area to image the remaining indents with greater detail. Shown here are non contact AFM typography images of a gold thin film surface. The thin film surface was found to consist of grains in the micrometer range.Each grain exhibits an atomically flat gold 111 surface consisting of large terraces and mono atomic steps. This gold 111 surface was indented four times by an AFM tip with a maximal vertical force of 7.2 micronewtons. The typographical difference between the two surfaces shows that the indents were the only major change to the surface.The projected area of each indent can be measured by masking the area with negative typography values relative to the unmarred surface. From this information, the hardness of the material can be calculated though it is likely to be underestimated because of elastic recovery. After watching this video, you should have a good understanding of how to determine the hardness of a metallic material at the true nanometer scale in under two hours.While attempting this procedure, it is important to remember to minimize the instrumental drift. To do so, successive imaging of an area to be indented can be performed prior to the measurements. After its development, this technique paved the way for researchers in the field of surface science to explore the atomistic mechanisms of plastic deformation in solid materials.

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The stiffness of the extracellular matrix strongly influences multiple behaviors of adherent cells.  Matrix stiffness varies spatially throughout a tissue, and undergoes modification in various disease conditions.  Here we develop methods to characterize spatial variations in stiffness in normal and fibrotic mouse lung tissue using atomic force microscopy microindentation.

Micro-Mechanical Characterization of Lung Tissue Using Atomic Force Microscopy

Source: Canovic, E. P., et al. Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry. J. Vis. Exp. (2016)This video demonstrates the use of atomic force microscopy (AFM) to measure the viscoelastic properties of brain tissue, where a cantilever with a spherical probe interacts with the tissue and bends under applied forces. A laser beam deflected onto a detector tracks the cantilever to measure indentation depth and...

Characterization of the Mechanical Properties of Mouse Brain Tissue Using Atomic Force Microscopy

This paper demonstrates a protocol to characterize the mechanical properties of living cells by means of microindentation using an Atomic Force Microscope (AFM).

Measuring the Mechanical Properties of Living Cells Using Atomic Force Microscopy

We present a set of techniques to characterize the viscoelastic mechanical properties of brain at the micro-, meso-, and macro-scales.

Characterizing Multiscale Mechanical Properties of Brain Tissue Using Atomic Force Microscopy, Impact Indentation, and Rheometry

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Use of Atomic Force Microscopy to Measure Mechanical Properties and Turgor Pressure of Plant Cells and Plant Tissues

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Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

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Application of Atomic Force Microscopy to Detect Early Osteoarthritis

The protocol presents a complete workflow for soft material nanoindentation experiments, including hydrogels and cells. First, the experimental steps to acquire force spectroscopy data are detailed; then, the analysis of such data is detailed through a newly developed open-source Python software, which is free to download from GitHub.

Experimental and Data Analysis Workflow for Soft Matter Nanoindentation

We present a step-by-step approach to identify and address the most common problems associated with atomic force microscopy micro-indentations. We exemplify the emerging problems on native human articular cartilage explants characterized by various degrees of osteoarthritis-driven degeneration.

Addressing Practical Issues in Atomic Force Microscopy-Based Micro-Indentation on Human Articular Cartilage Explants

Quantifying the contact area and force applied by an atomic force microscope (AFM) probe tip to a sample surface enables nanoscale mechanical property determination. Best practices to implement AFM cantilever-based nanoindentation in air or fluid on soft and hard samples to measure elastic modulus or other nanomechanical properties are discussed.

Atomic Force Microscopy Cantilever-Based Nanoindentation: Mechanical Property Measurements at the Nanoscale in Air and Fluid

Learn quantitative nano hardness measurement of gold thin films using instrumented AFM indentation. This technique reveals material strengths and plastic deformation mechanisms at the nanometer scale for nanomechanics research.

Quantitative Hardness Measurement by Instrumented AFM-indentation

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