Which of these is based on pH-sensitive chemical detection?
In electrophysiology toolkit, signal origin defines method classification. Patch-clamp directly measures ionic currents crossing membrane, voltage-sensitive dyes like ANEP translate electric field into fluorescence change, positron emission tomography detects photons from tracer annihilation. Each reports either electrical or radioactive signal. Approaches based on pH-sensitive probes monitoring proton concentration changes reflect acid-base chemistry, not primary electrophysiological current or potential. Among listed categories, no standard electrophysiological imaging or recording principle
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.
