Determining the Elastic Modulus of Compliant Thin Films Supported on Substrates from Flat Punch Indentation Measurements

Wald, Michael J.; Considine, John; Turner, Kevin T.

doi:10.1007/s11340-012-9705-2

Cited by 12 publications

(11 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As observed previously by Dimitriadis et al, substrate effects can cause significant overestimation in the elastic modulus (Dimitriadis et al, 2002). Recently, Wald et al have proposed a finite element solution for studying the indentation response of thin films using a flat punch (Wald et al, 2013). The primary focus of this paper was to demonstrate the feasibility in using piezoresistive force sensors for differentiating the force response in normal and cancerous specimens, not as much to characterize the elastic modulus of the tissue specimens.…”

Section: Resultsmentioning

confidence: 99%

Accurate characterization of benign and cancerous breast tissues: Aspecific patient studies using piezoresistive microcantilevers

Pandya¹,

Roy²,

Chen³

et al. 2015

Biosensors and Bioelectronics

View full text Add to dashboard Cite

Breast cancer is the largest detected cancer amongst women in the US. In this work, our team reports on the development of piezoresistive microcantilevers (PMCs) to investigate their potential use in the accurate detection and characterization of benign and diseased breast tissues by performing indentations on the micro-scale tissue specimens. The PMCs used in these experiments have been fabricated using laboratory-made silicon-on-insulator (SOI) substrate, which significantly reduces the fabrication costs. The PMCs are 260 μm long, 35 μm wide and 2 μm thick with resistivity of order 1.316 X 10−3 Ω-cm obtained by using boron diffusion technique. For indenting the tissue, we utilized 8 μm thick cylindrical SU-8 tip. The PMC was calibrated against a known AFM probe. Breast tissue cores from seven different specimens were indented using PMC to identify benign and cancerous tissue cores. Furthermore, field emission scanning electron microscopy (FE-SEM) of benign and cancerous specimens showed marked differences in the tissue morphology, which further validates our observed experimental data with the PMCs. While these patient aspecific feasibility studies clearly demonstrate the ability to discriminate between benign and cancerous breast tissues, further investigation is necessary to perform automated mechano-phenotyping (classification) of breast cancer: from onset to disease progression.

show abstract

Section: Resultsmentioning

confidence: 99%

Accurate characterization of benign and cancerous breast tissues: Aspecific patient studies using piezoresistive microcantilevers

Pandya¹,

Roy²,

Chen³

et al. 2015

Biosensors and Bioelectronics

View full text Add to dashboard Cite

show abstract

“…S3 where simultaneous force and contact area measurement were taken during loading and unloading. Optically transparent PDMS hemispheres of 2-3 mm diameter and height greater than 700 µm were used to avoid substrate effects from the hemisphere's sample mount [46,47]. The maximum load applied for every measurement was 1 mN and the cycle was completed with a constant velocity of 60 nm/sec.…”

Section: Contact Experiments Methodologymentioning

confidence: 99%

Linking energy loss in soft adhesion to surface roughness

Dalvi

Gujrati

Khanal

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

102

115

View full text Add to dashboard Cite

A mechanistic understanding of adhesion in soft materials is critical in the fields of transportation (tires, gaskets, seals), biomedicine, micro-contact printing, and soft robotics. Measurements have long demonstrated that the apparent work of adhesion coming into contact is consistently lower than the intrinsic work of adhesion for the materials, and that there is adhesion hysteresis during separation, commonly explained by viscoelastic dissipation. Still lacking is a quantitative experimentally validated link between adhesion and measured topography. Here, we used in situ measurements of contact size to investigate the adhesion behavior of soft elastic polydimethylsiloxane (PDMS) hemispheres (modulus ranging from 0.7 to 10 MPa) on four different polycrystalline diamond substrates with topography characterized across eight orders of magnitude, including down to the Ångström-scale. The results show that the reduction in apparent work of adhesion is equal to the energy required to achieve conformal contact. Further, the energy loss during contact and removal is equal to the product of intrinsic work of adhesion and the true contact area. These findings provide a simple mechanism to quantitatively link the widely-observed adhesion hysteresis to roughness rather than viscoelastic dissipation. Figure 1: Comprehensive topography characterization for four rough nanodiamond surfaces. The surface topography was measured using a multi-resolution approach that combines transmission electron microscopy (rightmost region of the curves), atomic force microscopy (intermediate region), and stylus profilometry (leftmost region). The nanodiamond surfaces are designated using the following nomenclature: ultrananocrystalline diamond (UNCD) is shown in red; nanocrystalline diamond (NCD) in black; microcrystalline diamond (MCD) in green, and a polished form of UNCD (polished UNCD) in blue. AFM images (of 5-micron lateral size) are shown in the left inset; TEM images are shown in the right inset. More than 50 measurements for each surface are combined using the power spectral density, which reveals the contribution to overall roughness from different length scales (wavelengths). These comprehensive descriptions of surface topography enable the determination of true surface area and stored mechanical energy due to the topography, which are necessary to understand adhesion.The model for (Eq. 4) is applied to the measured data as shown in Fig. 3A using 1 = 25 ± 5 mJ/m 2 [29,33]. The best correlation between the experimentally measured work of adhesion and the predictions of Eq. 4 was obtained using the intrinsic work of adhesion of 37.0 ± 3.7 mJ/m 2 (R 2 = 0.67). The explicit accounting for the change in area of the soft surface led to improved model predictions; if we do not account for this change (calculations shown in Supplemental Section 4) the best fit to the measured data is significantly poorer (R 2 = 0.29).

show abstract

“…In [6] an approximate analytical theory was proposed for the contact between a coated half-space and a randomly rough surface. Contacts between flat-ended cylindrical indenters and a flat coated half-space were studied in [7]. Theoretical results were compared with experimental data and will be used in the present paper for verification purposes.…”

Section: Introductionmentioning

confidence: 99%

Boundary element method for nonadhesive and adhesive contacts of a coated elastic half-space

Pohrt

Lyashenko

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part J:

View full text Add to dashboard Cite

We present a new formulation of the Boundary Element Method (BEM) for simulating the non-adhesive and adhesive contact between an indenter of arbitrary shape and an elastic halfspace coated with an elastic layer of different material. We use the Fast Fourier Transform based formulation of BEM, while the fundamental solution is determined directly in the Fourier space. Numerical tests are validated by comparison with available asymptotic analytical solutions for axisymmetric flat and spherical indenter shapes.

show abstract

Determining the Elastic Modulus of Compliant Thin Films Supported on Substrates from Flat Punch Indentation Measurements

Cited by 12 publications

References 16 publications

Accurate characterization of benign and cancerous breast tissues: Aspecific patient studies using piezoresistive microcantilevers

Accurate characterization of benign and cancerous breast tissues: Aspecific patient studies using piezoresistive microcantilevers

Linking energy loss in soft adhesion to surface roughness

Boundary element method for nonadhesive and adhesive contacts of a coated elastic half-space

Contact Info

Product

Resources

About