This work presents the design of the fully-dedicated core dice of an energy harvester-on-chip (HoC) with electrostatic transduction. The core dice has been fabricated by using a SOI-BASED MEMS technology which allows us to fix the problems found in the first prototype. The main highlights of this design are the use of ARCHITECH® software, which offers us the possibility of carrying out a parametric design by defining hierarchical blocks, and the advantage of using a SOI silicon layer of 60 μm to fabricate the mechanical suspensions, which increases the robustness and performance of the design. Simulations have been performed in order to validate the final design. Finally, several attempts of assembling the core dice together with a support substrate, by using an ad-hoc bonding technique, have been carrying out.