Fig. 3: The mode shapes and effective mechanical capacitance for a square membrane in the stress-governed regime.
The first (second) row in a shows the (k, l) mode shapes with uniform (non-uniform) biaxial tensile stress σx ≡ σy (σx ≠ σy). The mode numbers k and l presented in a are both odd numbers. b presents the mode shapes for mechanical (k, l) modes with odd mode number k and even number l. Similarly to a, the first and second rows correspond to uniform and non-uniform biaxial tensile stress cases, respectively. For odd k and even l, c, d schematically illustrate how the vertical mechanical oscillations of the degenerate-broken (k, l) and (l, k) modes induce changes in the corresponding mechanical capacitance, using k = 1 and l = 4 as an example.
