Recently, power harvesting technologies for low-power electronic devices have attracted much interest. In this paper,
the design and fabrication methods of a micro-electrostatic power generator is presented. This power generator
comprises a stator developed using an electret film for charge storage and a rotor covered by an interdigital electrode for
electric power generation. The newly developed electret material is made from mixing two solutions. The first solution
was made by blending polystyrene (PS) and cycloolefin copolymer (COC). The second solution was obtained by an
additive process as polar molecule was added into COC. This unique two solution electret method can easily be
integrated and adopted to the micro fabrication process. The charge storage capability of this new electret material was
investigated and results showed that low concentration of polystyrene in the blended material will not only have more
stable but also higher electrostatic charge than that of pure COC. In addition, the polar molecular additives also improve
the electret properties of COC due to micro-cavities formation and the interactions between molecules and polymer. Our
newly developed blended electret material has excellent mechanical properties and is easy to use when compared to
using Teflon Fluorinated Ethylene Propylene (FEP) and polypropylene (PP). A feasibility study of a micro electrostatic
power generator based on our blended electret material was performed. Experimental results demonstrate the feasibility
and effectiveness of this new type of micro electrostatic power generator.
To power the tiny sensor devices by MEMS generator which scavenging energy from ambient vibrations is becoming
practical due to the power consumption of low power electronics is going down to tens to hundreds μW for integrated
wireless sensor devices. In this paper, we are going to present the development on two different types of piezoelectric
MEMS generators that have the ability to scavenge mechanical energy of ambient vibrations and transform it into
electrical energy. These two piezoelectric MEMS generators are both cantilever type made of silicon process and
transform energy with thin PZT layer. However, the first one is with the interdigital electrodes on the top and the other
one is with laminated electrodes sandwiched the PZT layer. The theoretical prediction and the process development for
the two types of generators will all be presented; the evaluation and comparison of the two generators will also be
detailed.
The power harvesting technologies for low-power electronic devices, such as wireless sensor networks and biomedical
sensor applications, have received a growing attention in recent years. Of all possible energy sources such as
mechanical vibrations, electromagnetic radiations and magnetic fields, the mechanical vibrations have been considered a
promising choice for power harvesting in a wide variety of applications. This paper presents the development of two
different piezoelectric MEMS generators to harvest energy at different vibration frequencies. For power harvesting at
1.5kHz vibration frequency, we present a generator comprising a silicon micro-cantilever with laminated PZT (lead
zirconate titanate) material, and the interdigital electrode on the top of the PZT layer to transform mechanical strain
energy into electrical charges by using the d33 mode of PZT. The piezoelectric cantilever generator was tested with
using a shaker as the external vibration source. For power harvesting at frequency higher than 20kHz, we present a
piezoelectric disk-shaped generator which is packaged by cohesive gel. The power generation efficiency of the
fabricated devices was characterized. For the application of the power to the implanted medical sensors, the
piezoelectric MEMS generator is claimed to be a power receiver of an additional vibration sources. An experimental
model was also developed to study the power transmission efficiency and the charge ability of the MEMS generator
device. A feasibility study of the piezoelectric MEMS generator as a power receiver was performed and some testing
results are presented.
Over the years, there has been a growing interest in the field of power harvesting technologies for low-power electronic devices, such as wireless sensor networks and biomedical sensor applications. Of all possible energy sources, the mechanical vibrations have been considered a potential choice for power harvesting in a wide variety of applications. This paper presents the development of a piezoelectric MEMS generator which has the ability to scavenge mechanical energy of ambient vibrations from their surroundings and transform it into electrical energy that can be used in energy storage applications. The piezoelectric MEMS generator comprises a beam structure based on the silicon wafer, and the digitate electrode placed in between the lead zirconate titanate (Pb(Zr,Ti) O3, PZT) material and the beam structure, to transform mechanical strain energy into electrical charge with using the d33 mode of PZT. An optional proof mass can be built at the tip of the beam, to adjust the structure resonant frequency of the piezoelectric MEMS generator, for most adaptable frequency matching to the ambient vibration of its surroundings. A theoretical model is also presented to investigate the relations between the charge generation ability and the design parameters of the piezoelectric MEMS generator. To improve the piezoelectric MEMS generator fabrication process, a self-made PZT deposition chamber which could deposit PZT thin film up to tens micron in minutes was used to deposit the piezoelectric layer on the beam structure of the piezoelectric MEMS generator.
Over the past years, there has been growing interests in the field of power harvesting technologies for low-power electronic devices such as wireless sensor networks and biomedical sensor applications. Methodologies of using piezoelectricity to convert mechanical power to electric power with a cantilever beam excited by external environmental vibration were widely discussed and examined. Operating in resonant mode of the cantilever beam was found to be the most efficient power harvesting condition, but in most cases that the resonant frequencies of the cantilever beam are hardly matching with the frequency of external vibration sources. The mechanical resonant has relatively high Q factor, and thus the harvesting output will be significantly lower compared to the condition when resonant matching to external vibration frequency. A tunable resonant frequency power harvesting device in cantilever beam form which will shift its resonant frequency to match that of the external vibrations will be developed and verified in this paper. This system utilizes a variable capacitive load to shift the gain curve of the cantilever beam and a low power microcontroller will sampling the external frequency and adjust the capacitive load to match external vibration frequency in real-time. The underlying design thoughts, methods developed, and preliminary experimental results will be presented. Potential applications of this newly developed power harvesting to wireless sensor network will also be detailed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.