The quest to realize a particle accelerator on a chip has led to the emergence of dielectric laser accelerators (DLAs). DLAs have the capability for sustaining accelerating gradients in the GV/m regime using grating-shaped dielectric microstructures. The geometry of these microstructures is one of the decisive features affecting the accelerating gradient and energy gain. Here we present an optimization study comparing the performance of different geometrical configurations of dielectric microstructures through particle in cell (PIC) simulations, for both non-relativistic and relativistic regimes. Assuming electron beams with energies of 28 keV and 1 MeV, excited by a laser with a wavelength of 2 ¼m, pulse length of 100 fs and electric field of 1.5 GV/m, we show that even when grating parameters are the same, the design of the shape/structure plays a crucial role in the enhancement of energy gain and efficiency.