  We construct a simple algorithm to derive number density of spin 1/2
particles created in spatially flat FLRW spacetimes and resulting renormalized
energy-momentum tensor within the framework of adiabatic regularization.
Physical quantities thus found are in agreement with the known results. This
formalism can be considered as an appropriate extension of the techniques
originally introduced for scalar fields, applicable to fermions in curved
space. We apply this formalism to compute the particle number density and the
renormalized energy density and pressure analytically (wherever possible) and
numerically, in two interesting cosmological scenarios: a de Sitter spacetime
and a radiation dominated universe. Results prove the efficiency of the
methodology presented here.
