  Strain is attracting much interest as a mean to tune the properties of thin
exfoliated two-dimensional materials and their heterostructures. Numerous
devices to apply tunable uniaxial strain are proposed in the literature, but
only few for biaxial strain where there is often a trade-off between maximum
strain and uniformity, reversibility and device size. We present a compact
device that allows the controlled application of uniform in-plane biaxial
strain, with maximum deformation and uniformity comparable to those found in
much larger devices. Its performance and strain uniformity over the sample area
are modeled using finite element analysis and demonstrated by measuring the
response of exfoliated 2H-MoS$_2$ to strain by Raman spectroscopy.
