Easy and direct method for calibrating atomic force microscopy lateral force measurements

Liu, Wenhua; Bonin, Keith; Guthold, Martin

doi:10.1063/1.2745733

Cited by 79 publications

(64 citation statements)

References 38 publications

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“…This technique is well calibrated as demonstrated by Liu et al [49]. Lateral force was determined using F l =K C ⋅ I l , where I l is the left-right photodiode signal, and K C is the lateral force constant.…”

Section: Lateral Force Stress and Strain Measurements On Single Fibersmentioning

confidence: 99%

Determining the mechanical properties of electrospun poly-ε-caprolactone (PCL) nanofibers using AFM and a novel fiber anchoring technique

Baker

Banerjee

Bonin

et al. 2016

Materials Science and Engineering: C

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193

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Due to its low cost, biocompatibility and slow bioresorption, poly-ε-caprolactone (PCL) continues to be a suitable material for select biomedical engineering applications. We used a combined atomic force microscopy (AFM)/optical microscopy technique to determine key mechanical properties of individual electrospun PCL nanofibers with diameters between 440-1040nm. Compared to protein nanofibers, PCL nanofibers showed much lower adhesion, as they slipped on the substrate when mechanically manipulated. We, therefore, first developed a novel technique to anchor individual PCL nanofibers to micrometer-sized ridges on a substrate, and then mechanically tested anchored nanofibers. When held at constant strain, tensile stress relaxed with fast and slow relaxation times of 1.0±0.3s and 8.8±3.1s, respectively. The total tensile modulus was 62±26MPa, the elastic (non-relaxing) component of the tensile modulus was 53±36MPa. Individual PCL fibers could be stretched elastically (without permanent deformation) to strains of 19-23%. PCL nanofibers are rather extensible; they could be stretched to a strain of at least 98%, and a tensile strength of at least 12MPa, before they slipped off the AFM tip. PCL nanofibers that had aged for over a month at ambient conditions became stiffer and less elastic. Our technique provides accurate nanofiber mechanical data, which are needed to guide construction of scaffolds for cells and other biomedical devices.

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Section: Lateral Force Stress and Strain Measurements On Single Fibersmentioning

confidence: 99%

Determining the mechanical properties of electrospun poly-ε-caprolactone (PCL) nanofibers using AFM and a novel fiber anchoring technique

Baker

Banerjee

Bonin

et al. 2016

Materials Science and Engineering: C

Self Cite

193

View full text Add to dashboard Cite

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“…The experimentally determined values of α l at a V l of 0 V for the cantilevers used are listed in 57 The experimentally determined SD of α l for each cantilever (3.2% to 15%) were typically less than this predicted maximum uncertainty (as detailed in Table 2). …”

Section: Lateral Conversion Factors Of Cantilevers Usedmentioning

confidence: 99%

“…The calibration method used here was adapted from that described by Liu et al 57 Glass fibres with radii of less than 1 µm and lengths of more than 150 µm were extracted from an Advantec GA-55 binder free glass fibre filter. Individual fibres were positioned over the edge of a glass slide using a micromanipulator then glued in place using epoxy.…”

Section: Afm Cantilever Lateral Force Calibrationmentioning

confidence: 99%

“…We introduce a method for fixing individual nanofibres across a gap that does not require additional handling of the fibres. We use the lateral movement of the AFM cantilever to enable tensile testing of the suspended fibres to high strains and apply the lateral force calibration method proposed by Liu and co-workers 57 because of its geometric similarity to the fibre test. We further expand the calibration method to account for the inherent non-linearity of the AFM sensor and variable fibre / cantilever tip contact point.…”

Section: Introductionmentioning

confidence: 99%

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Tensile testing of individual glassy, rubbery and hydrogel electrospun polymer nanofibres to high strain using the atomic force microscope

et al. 2013

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The production and use of polymer nanofibre assemblies prepared by electrospinning is now widespread. It is known that the tensile properties of electrospun polymer fibres can be different to those of bulk polymers. Here, we report a general method for measuring the tensile properties of individual electrospun nanofibres that employs a commercial atomic force microscope. Methods for preparing samples, force calibration and calculation of tensile stress and strain are described along with error estimation. By appropriate choice of AFM cantilever, it is shown that the tensile stress-strain curves can be measured for glassy, rubbery and gel polymer nanofibres. Testing can be in air or fluid and to strains of 300%. Example results illustrate the usefulness of the technique with the observation of high ductility in normally brittle glassy polymers such as polystyrene, and unusually large hysteresis in thermoplastic elastomer nanofibres. These observations provide new insights into the structure and mechanical behaviour of nanoscale polymeric materials. 2013 Elsevier Ltd. All rights reserved. AbstractThe production and use of polymer nanofibre assemblies prepared by electrospinning is now

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“…The one-step method, [2][3][4][5][6][7][8][9] bypassing difficulties in the separate measurement of the lateral stiffness of the cantilever and lateral sensitivity of the photodiode, directly determines the conversion factor between the lateral force and lateral photodiode response. The two-step method, which is similar to the normal force calibration, involves the calibration of the cantilever's torsional spring constant [10][11][12][13] and the sensitivity of the lateral photodiode response.…”

mentioning

confidence: 99%

Optical lever calibration in atomic force microscope with a mechanical lever

Xie

Vitard

Haliyo

et al. 2008

Review of Scientific Instruments

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A novel method that uses a small mechanical lever has been developed to directly calibrate the lateral sensitivity of the optical lever in the atomic force microscope (AFM). The mechanical lever can convert the translation into a nanoscale rotation angle with a flexible hinge that provides an accurate conversion between the photodiode voltage output and torsional angle of a cantilever. During the calibration, the cantilever is mounted on a holder attached on the lever, which brings the torsional axis of the cantilever and rotation axis of the lever into line. By making use of its nanomotion on the Z-axis and using an external motion on the barrier, this device can complete the local and full-range lateral sensitivity calibrations of the optical lever without modifying the actual AFM or the cantilevers.

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Easy and direct method for calibrating atomic force microscopy lateral force measurements

Cited by 79 publications

References 38 publications

Determining the mechanical properties of electrospun poly-ε-caprolactone (PCL) nanofibers using AFM and a novel fiber anchoring technique

Determining the mechanical properties of electrospun poly-ε-caprolactone (PCL) nanofibers using AFM and a novel fiber anchoring technique

Tensile testing of individual glassy, rubbery and hydrogel electrospun polymer nanofibres to high strain using the atomic force microscope

Optical lever calibration in atomic force microscope with a mechanical lever

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