Theory 30/Single-Molecule Biophysics
Force Sensitivity Is a Stiffness Ratio
The claim
The force resolution of a single-molecule trap is set by the ratio of trap stiffness to thermal noise rather than by the sensor's displacement resolution.
01The mechanism
Force is stiffness times displacement; softer traps convert thermal motion into larger displacements, so the ratio sets the smallest resolvable force.
02Predictions
- P1Force resolution should track the ratio.
- P2Displacement resolution alone should mispredict.
03Refutation
Force resolution tracking displacement resolution would remove stiffness.