651 research outputs found
3D Energy Harvester Evaluation
This paper discusses the characterization and evaluation of an MEMS based electrostatic generator, a part of the power supply unit of the self-powered microsystem[1,2,3]. The designed generator is based on electrostatic converter and uses the principle of conversion of non-electric energy into electrical energy by periodical modification of gap between electrodes of a capacitor [4]. The structure is designed and modeled as three-dimensional silicon based MEMS. Innovative approach involving the achievement of very low resonant frequency of the structure (about 100Hz) by usage of modified long cantilever spring design, minimum area of the chip, 3D work mode, the ability to be tuned to reach desired parameters, proves promising directions of possible further development
Power Processing for Electrostatic Microgenerators
Microgenerators are electro-mechanical devices which harvest energy from local environmental
from such sources as light, heat and vibrations. These devices are used to
extend the life-time of wireless sensor network nodes. Vibration-based microgenerators
for biomedical applications are investigated in this thesis.
In order to optimise the microgenerator system design, a combined electro-mechanical
system simulation model of the complete system is required. In this work, a simulation
toolkit (known as ICES) has been developed utilising SPICE. The objective is to
accurately model end-to-end microgenerator systems. Case-study simulations of electromagnetic
and electrostatic microgenerator systems are presented to verify the operation
of the toolkit models. Custom semiconductor devices, previously designed for microgenerator
use, have also been modelled so that system design and optimisation of complete
microgenerator can be accomplished.
An analytical framework has been developed to estimate the maximum system effectiveness
of an electrostatic microgenerator operating in constant-charge and constant-voltage
modes. The calculated system effectiveness values are plotted with respect to microgenerator
sizes for different input excitations. Trends in effectiveness are identified and
discussed in detail. It was found that when the electrostatic transducer is interfaced with
power processing circuit, the parasitic elements of the circuit are reducing the energy generation
ability of the transducer by sharing the charge during separation of the capacitor
plates. Also, found that in constant-voltage mode the electrostatic microgenerator has a
better effectiveness over a large operating range than constant-charge devices. The ICES
toolkit was used to perform time-domain simulation of a range of operating points and
the simulation results provide verification of the analytical results
Design and Fabrication of 3D Electrostatic Energy Harvester
This paper discusses the design of an electrostatic generator, power supply component of the self-powered microsystem, which is able to provide enough energy to power smart sensor chains or if necessary also other electronic monitoring devices. One of the requirements for this analyzer is the mobility, so designing the power supply expects use of an alternative way of getting electricity to power the device, rather than rely on periodic supply of external energy in the form of charging batteries, etc. In this case the most suitable method to use is so-called energy harvesting â a way how to gather energy. This uses the principle of non-electric conversion of energy into electrical energy in the form of converters. The present study describes the topology design of such structures of electrostatic generator. Structure is designed and modeled as a three-dimensional silicon based MEMS. Innovative approach involving the achievement of very low resonant frequency of the structure, while the minimum area of the chip, the ability to work in all 3 axes of coordinate system and ability to be tuned to reach desired parameters proves promising directions of possible further development of this issue. The work includes simulation of electro-mechanical and electrical properties of the structure, description of its behavior in different operating modes and phases of activity. Simulation results were compared with measured values of the produced prototype chip. These results can suggest possible modifications to the proposed structure for further optimization and application environment adaptation
Thermal and Mechanical Energy Harvesting Using Lead Sulfide Colloidal Quantum Dots
The human body is an abundant source of energy in the form of heat and mechanical movement. The ability to harvest this energy can be useful for supplying low-consumption wearable and implantable devices. Thermoelectric materials are usually used to harvest human body heat for wearable devices; however, thermoelectric generators require temperature gradient across the device to perform appropriately. Since they need to attach to the heat source to absorb the heat, temperature equalization decreases their efficiencies. Moreover, the electrostatic energy harvester, working based on the variable capacitor structure, is the most compatible candidate for harvesting low-frequency-movement of the human body. Although it can provide a high output voltage and high-power density at a small scale, they require an initial start-up voltage source to charge the capacitor for initiating the conversion process. The current methods for initially charging the variable capacitor suffer from the complexity of the design and fabrication process.
In this research, a solution-processed photovoltaic structure was proposed to address the temperature equalization problem of the thermoelectric generators by harvesting infrared radiations emitted from the human body. However, normal photovoltaic devices have the bandgap limitation to absorb low energy photons radiated from the human body. In this structure, mid-gap states were intentionally introduced to the absorbing layer to activate the multi-step photon absorption process enabling electron promotion from the valence band to the conduction band. The fabricated device showed promising performance in harvesting low energy thermal radiations emitted from the human body.
Finally, in order to increase the generated power, a hybrid structure was proposed to harvest both mechanical and heat energy sources available in the human body. The device is designed to harvest both the thermal radiation of the human body based on the proposed solution-processed photovoltaic structure and the mechanical movement of the human body based on an electrostatic generator. The photovoltaic structure was used to charge the capacitor at the initial step of each conversion cycle. The simple fabrication process of the photovoltaic device can potentially address the problem associated with the charging method of the electrostatic generators. The simulation results showed that the combination of two methods can significantly increase the harvested energy
Electrostatic Conversion for Vibration Energy Harvesting
This chapter focuses on vibration energy harvesting using electrostatic
converters. It synthesizes the various works carried out on electrostatic
devices, from concepts, models and up to prototypes, and covers both standard
(electret-free) and electret-based electrostatic vibration energy harvesters
(VEH).Comment: This is an author-created, un-copyedited version of a chapter
accepted for publication in Small-Scale Energy Harvesting, Intech. The
definitive version is available online at: http://dx.doi.org/10.5772/51360
Please cite as: S. Boisseau, G. Despesse and B. Ahmed Seddik, Electrostatic
Conversion for Vibration Energy Harvesting, Small-Scale Energy Harvesting,
Intech, 201
Maximum Effectiveness of Electrostatic Energy Harvesters When Coupled to Interface Circuits
Accepted versio
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