Uniaxial Strain-Dependent Resonant Raman Scattering in WS₂

2D transition metal dichalcogenides (TMDCs) have attracted immense interest due to their remarkable optical and electronic properties. The exceptional mechanical strength and flexibility of these materials enable the modification and tunability of their properties through applied strain, providing a fertile platform for fundamental studies and advanced flexible device applications. Herein, the phononic and excitonic properties of tungsten disulfide (WS₂) flakes under uniaxial tensile strain are investigated using Raman spectroscopy. In sharp contrast to a previous report on a monolayer of chemical vapor deposition grown WS₂, the measurements on exfoliated single crystals of WS₂ show an intriguing dome-like feature in the Raman intensity over strain. Such a behavior can be attributed to the strain-induced tuning of the excitonic levels that resonate with the laser excitation line at specific strain, implying its plausible sensor applications. Furthermore, to demonstrate this proof-of-concept, the Raman intensity is used to map the spatial variation of strain in intentionally wrinkled WS₂ flake. The study provides the means to investigate the effect of strain on the phononic and (opto-)electronic properties of WS₂ and demonstrates its potential stain-sensor application.