extractStiffness: Extract Sample Stiffness From Force Curves
In nstone8/Rasylum: Rasylum: AFM Data Analysis in R

Perform a fit of force curves to a Hertzian contact model to estimate the Young's modulus of a sample.

extractStiffness(case,r,approachLength=.1,contactLength=.1,
  searchWidth=.2,maxF=.5,weight=4,correctVirtDefl=TRUE,zPos="zSensr",
  force="force")
parExtractStiffness(cases,r,approachLength=.1,contactLength=.1,
  searchWidth=.2,maxF=.5,weight=4,correctVirtDefl=TRUE,zPos="zSensr",
  force="force",numCores=-1)

`case`	One entry of the list produced by `loadPreSorted` or `readARDF` containing the force curve to be fit to the Hertzian Contact Model
`r`	Radius of the spherical indenter used, in meters
`approachLength`	Percent of the approach curve that can be safely assumed not to be in contact with the sample
`contactLength`	Percent of the approach curve that can be safely assumed to be in contact with the sample
`searchWidth`	Percent of the curve on either side of a rough guess to search for the contact point. A warning will be triggered if the contact point is not detected in the middle 50 percent of this range
`maxF`	Upper bound on fit region, in terms of percentage of the maximum force
`weight`	Relative weight to apply to the residual of the linear portion of the fit as compared to the nonlinear portion. Increasing this value will tend to bring the contact point closer to the approach line.
`correctVirtDefl`	If `TRUE`, attempt to correct for non-flat non-contact portions of the approach curve
`zPos`	The name of the columns in `case$data` containing the z position data
`force`	the name of the columns in `case$data` containing the force data
`cases`	An object of the type produced by `loadPreSorted` containing the force curves to be fit to the Hertzian Contact Model
`numCores`	Number of cores to use for the computation. If `numCores`==-1 all available cores will be used

An object containing the extracted stiffness values, fit residuals and the fit curves themselves. The fit curves which will have been corrected in order to place the detected contact point at (0,0). Fit curves can be saved using saveFits, other data can be formatted into a human-readable data.frame using collateFits.

nstone8/Rasylum documentation built on May 9, 2019, 8:18 a.m.