This paper reports results on the effect of interaction of Ag+ on ID droplet array spacing and the repulsive forces between stimuli-responsive nanoemulsion droplets, stabilized with an anionic surfactant-sodium dodecyl sulfate-and a diblock polymer-poly(vinyl alcohol)-vinyl acetate. The repulsive interaction is probed by measuring the in-situ equilibrium force-distance in the presence of Ag+ using the magnetic chaining technique. At a constant static magnetic field, emulsion droplets form ID array that diffract visible light. A large blue-shift in the diffracted light is observed in the presence of interacting Ag+ because of the reduction in the interdroplet spacing within the ID array. The in-situ equilibrium force-distance measurement results show that the onset of repulsions and magnitude of repulsive forces are strongly influenced by the presence of Ag+ in ppb levels. This suggests that the Ag+ ions screen the surface charges through the formation of both Stern and diffuse electric double layer and produces a dramatic blue-shift in surfactant-stabilized emulsion, whereas a dramatic conformational change in the adsorbed polymer layer causes a reduction in the ID array spacing in the diblock polymer stabilized emulsion. The force-distance results are compared with the predictions of electrical double-layer and repulsive steric forces. The droplet array shows an excellent selectivity to Ag+ due to the strong interaction of Ag+ with the stabilizing moieties at the oil-water interface. The possible mechanisms of interaction of Ag+ with surfactant and polymer are discussed. The dramatic decrease in the ID array spacing in the presence of Ag+ may find promising practical applications in the development of optical sensors for selective detection of cations with ultrahigh sensitivity.