In this paper we explore the potential that the use of state-of-the-art Nano-Electro-Mechanical (NEM) devices, i.e., NEMFETs and NEM Relays, in the implementation of power management circuitry, in combination with efficient energy harvesters through 3D stacking integration, have in meeting the tight energy budgets of “Zero-Energy” autonomous sensor systems. We propose various 3D hybrid embodiments of an openMPS430 embedded processor augmented with NEMFET and/or NEM Relay based power management mechanisms and investigate their energy consumption when executing a heart beat detection application. Our investigations indicate that the hybrid NEMFET-oriented approach, which relies on sleep transistors and associated management logic implemented on a dedicated NEMFET die, is the most promising in terms of energy consumption and reliability. Moreover, when combined with a thermal energy harvester, potentially implementable on the same die, it can enable the road towards autonomous computing.