Local strain engineering is a promising technique to tune the properties of two-dimensional materials at the nanoscale. However, many existing methods are static and limit the systematic exploration of strain-dependent material behavior. Here, we demonstrate dynamic and reversible control of local strain distributions in suspended trilayer tungsten disulfide (WS2) via nanoindentation using a micro-mechanical spring patterned with nanoscale probes. Micro-photoluminescence measurements reveal that indentation using a ring-shaped probe induces a nearly uniform biaxial strain distribution accompanied by a reversible redshift of the neutral exciton peak, consistent with simulated strain magnitudes. We further show that the in-plane strain distribution is spatially programmable by engineering the probe geometry and present designs for inducing point-like, uniaxial, biaxial, and triaxial strain distributions. The presented platform enables substrate-free, repeatable local strain engineering in suspended 2D materials and provides a versatile tool for streamlining the investigation of strain-dependent phenomena.
@article{arxiv.2507.07784,
title = {Reversible local strain engineering of $\mathrm{WS}_2$ using a micro-mechanical spring},
author = {Eric Herrmann and Zhixiang Huang and Sai Rahul Sitaram and Ke Ma and S M Jahadun Nobi and Xi Wang},
journal= {arXiv preprint arXiv:2507.07784},
year = {2025}
}