  We propose a \emph{model-independent} approach to study entanglement creation
due to the dynamics between two asymptotic quantum regimes in the framework of
homogeneous and isotropic universe. We realize it by Pad\'e expansion to
reconstruct the functional form of scale factor, rather than postulating it a
priori.This amounts to fix the Pad\'e approximants constraining the free
parameters in terms of current cosmic observations. Assuming fermions, we solve
the Dirac equation for massive particles and we investigate entanglement
entropy in terms of modes $k$ and mass $m$. We consider two rational
approximations of (1,1) and (1,2) orders, which turn out to be the most
suitable choices for guaranteeing cosmic bounds. Our results show qualitative
agreement with those known in literature and arising from toy models, but with
sensible quantitative discrepancies. Moreover, our outcomes are model
independent reconstructions which show that any higher orders departing from
(1,1) do not significantly modify particle-antiparticle production (hence
entanglement), if cosmic bounds are taken into account.
