This package aims to help you understand the limitations of quantatative measurements with two-state ratiometric sensors.
You can load sensor spectra information into an object, take ratio measurements from that spectra, convert those ratio measurements into biophysically-meaningful values (e.g. fraction protenated and pH or fraction oxidized and redox potential), and then analyze how errors in ratio measurements affect the errors in those values.
You can install the package from within R with the
You can then load the package like any other.
Building a sensor
You can build a sensor by one of two methods:
- By using a spectra, usually provided as a .csv file of excitation-emission values
# Build a spectra object from a csv file spectra_file <- read.csv("spectra.csv", header = FALSE) spectra <- spectraMatrixFromValues( lambdas_minimum = spectra_file, values_minimum = spectra_file, lambdas_maximum = spectra_file, values_maximum = spectra_file ) # After building a spectra, I need to specify my ratiometric emission bands # in this case, I'll specify (410 nm +/- 10 nm) / (470 nm +/- 10 nm) my_sensor <- newSensorFromSpectra(spectra, lambda_1 = c(400, 420), lambda_2 = c(460, 480))
- By using empirically-determined Rmin, Rmax, and delta values
my_sensor <- new("Sensor", Rmin = 1, Rmax = 5, delta = 0.2)
Once you have a generic sensor, you can create a more specalized sensor by passing specalization-specific parameters.
For example, to make a redox sensor, I need to pass a midpoint potential, e0:
my_redox_sensor <- new("redoxSensor", my_sensor, e0 = -250)
Computing accurate ranges
One of the big outputs of this package is a plot that specifies tha accuracy of a given sensor at certain levels of microscopy precision.
To generate that output, you can call plotRanges() on a sensor object.
Right now, that range plot is only enabled for redoxSensors. For other sensors, hold tight (or, if you want them sooner, please email me at julianstanleya [at] gmail [dot] com and I'll majorly expedite the process!)
For example, here is how you would create that plot for the redox sensor created above, across microscope inaccuracies ranging from 2% to 8% relative error, at "acceptable error" thesholds of 1-5mV:
library(sensorOverlord) # Ranges plot of a sensor at different inaccuracies and thresholds rangePlot(my_redox_sensor, ranges = ranges_df(my_redox_sensor, inaccuracies = seq(0.02, 0.08, by = 0.01), thresholds = 1:5))