The increasing interest in the Internet of Things (IoT) has led to the rapid development of low-power sensors and wireless networks. However, there are still several barriers that make a global deployment of the IoT difficult. One of these issues is the energy dependence, normally limited by the capacitance of the batteries. A promising solution to provide energy autonomy to the IoT nodes is to harvest residual energy from ambient sources, such as motion, vibrations, light, or heat. Mechanical energy can be converted into electrical energy by using piezoelectric transducers. The piezoelectric generators provide an alternating electrical signal that must be rectified and, therefore, needs a power management circuit to adapt the output to the operating voltage of the IoT devices. The bonding and packaging of the different components constitute a large part of the cost of the manufacturing process of microelectromechanical systems (MEMS) and integrated circuits. This could be reduced by using a monolithic integration of the generator together with the circuitry in a single chip. In this work, we report the optimization, fabrication, and characterization of a vibration-driven piezoelectric MEMS energy harvester, and the design and simulation of a charge-pump converter based on a standard complementary metal–oxide–semiconductor (CMOS) technology. Finally, we propose combining MEMS and CMOS technologies to obtain a fully integrated system that includes the piezoelectric generator device and the charge-pump converter circuit without the need of external components. This solution opens new doors to the development of low-cost autonomous smart dust devices.

Triboelectric nanogenerators (TENGs) have emerged as potential energy‐harvesting modules for miniaturized devices. TENG modules are derived often from components having low sustainability whereas the current environmental and economic circumstances demand a focus on sustainable, ecologically friendly approaches for the development of advanced hybrid materials. Herein, recycled polyethylene terephthalate (PET) along with commercially available nylon are electrospun into nanofibers for TENG devices. The obtained nanofibers are characterized using microscopy, spectroscopy, and thermal and mechanical analysis. Electrospinning of pristine and titanium dioxide nanoparticles (TiO ₂ NPs) blended polymer solutions resulted in uniform nanofibers without beads. The addition of TiO ₂ NPs improved the thermal properties and significantly improved the mechanical stability of the nanofibers. The performance of the fabricated TENG device has been improved by functionalizing the nanofibers with TiO ₂ NPs. Particularly, the combination of pristine PET and TiO ₂ NPs (5%) functionalized nylon nanofibers reached a peak power density of 23.44 mW m ^{− 2} with a surface charge density of 6.81 µC m ^{− 2} , a max output voltage of 111 V and a max current of −1.61µA. This study opens a new avenue to utilize upcycled cost‐effective polymers processed using electrospinning as a powerful tool for the fabrication of the next generation of sustainable TENG devices.

The rapid increase of the Internet of Things (IoT) has led to significant growth in the development of low-power sensors. However; the biggest challenge in the expansion of the IoT is the energy dependency of the sensors. A promising solution that provides power autonomy to the IoT sensor nodes is energy harvesting (EH) from ambient sources and its conversion into electricity. Through 3D printing, it is possible to create monolithic harvesters. This reduces costs as it eliminates the need for subsequent assembly tools. Thanks to computer-aided design (CAD), the harvester can be specifically adapted to the environmental conditions of the application. In this work, a piezoelectric resonant energy harvester has been designed, fabricated, and electrically characterized. Physical characterization of the piezoelectric material and the final resonator was also performed. In addition, a study and optimization of the device was carried out using finite element modeling. In terms of electrical characterization, it was determined that the device can achieve a maximum output power of 1.46 mW when operated with an optimal load impedance of 4 MΩ and subjected to an acceleration of 1 G. Finally, a proof-of-concept device was designed and fabricated with the goal of measuring the current passing through a wire.

One of the main difficulties for a global implantation of the Internet of Things (IoT) is the energy dependence of the nodes, limited by the battery’s lifetime. Energy harvesting seems to be a promising solution to provide energy autonomy to IoT nodes. Power management circuits are needed to collect and store the charges scavenged form the ambient sources. In addition, this circuit needs to adapt the output voltage to power the wireless sensor node. Because of the typical heterogeneity of the system, the cost and difficulties associated to the encapsulation of the CMOS chip and the energy harvester can be important. They could be reduced by using a monolithic integration of both parts in a single chip or package. In this work, we propose a fully monolithically integrated system comprised by a power management circuit, a piezoelectric microgenerator and a storage capacitor. With this solution, which combines MEMS and CMOS technologies, we pave the way to the future development of autonomous smart dust.