afmToolkit (version 1.0.0)

afmZeroPointSlope: Zero Force Point and Slope

Description

This function finds the point of zero force (real contact point) and the slope of the contact part of the Force-Distance curve.

Usage

afmZeroPointSlope(
  afmdata,
  fstar = 0,
  segment = c("approach", "retract"),
  silent = FALSE
)

Value

An afmdata class variable which will consist on the original input

afmdata variable plus a new list named Slopes with the following fields: Z0Point: Point of zero force. Slope: Slope of the best fit line in the contact part of the Force-Distance curve.

Arguments

afmdata

An afmdata object. It should be a valid afmdata object upon which the Contact Point and the baseline correction must have been calculated first (using functions afmContactPoint() and afmBaselineCorrection())

fstar

Value such that fstar * sd is to be considered as zero Force, where sd is the standard deviation of Force at the basline. It takes fstar = 0 as default value, meaning that zero force is actually zero.

segment

The segment on which everything is calculated.

silent

Logical value. If TRUE suppresses the message indicating the name of the curve being processed (useful for batch-processing large number of curves). Defaults to FALSE

Examples

data <- afmReadJPK("force-save-JPK-2h.txt.gz", path = path.package("afmToolkit"))
data <- afmContactPoint(data, width = 20, mul1 = 1, mul2 = 20)
data <- afmDetachPoint(data, width = 40, mul1 = 3, mul2 = 40)
data <- afmBaselineCorrection(data)
data <- afmZeroPointSlope(data, segment = "approach")
if (FALSE) {
plot(data, segment = "approach") + geom_vline(xintercept = data$Slopes$Z0Point, lty = 2)
}