Piezoelectric energy harvesting from ambient vibrations is well studied, but harvesting from quasi-static responses is not yet fully explored. The lack of attention is because quasi-static actions are much slower than the resonance frequency of piezoelectric oscillators to achieve optimal outputs; however, they can be a common mechanical energy resource: from large civil structure deformations to biomechanical motions. The recent advances in bio-micro-electro-mechanical systems and wireless sensor technologies are motivating the study of piezoelectric energy harvesting from quasi-static conditions for low-power budget devices. This article presents a new approach of using quasi-static deformations to generate electrical power through an axially compressed bilaterally constrained strip with an attached piezoelectric layer. A theoretical model was developed to predict the strain distribution of the strip’s buckled configuration for calculating the electrical energy generation. Results from an experimental investigation and finite element simulations are in good agreement with the theoretical study. Test results from a prototyped device showed that a peak output power of 1.33 μW/cm2was generated, which can adequately provide power supply for low-power budget devices. And a parametric study was also conducted to provide design guidance on selecting the dimensions of a device based on the external embedding structure.
- Award ID(s):
- 1408005
- PAR ID:
- 10091622
- Date Published:
- Journal Name:
- Shock and Vibration
- Volume:
- 2019
- ISSN:
- 1070-9622
- Page Range / eLocation ID:
- 1 to 10
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
more » « less
Abstract Bistable elements are candidate structures for the evolving field of MEMS-based no-power event-driven sensors. In this paper, we present a strategy for producing bistable elements and investigate two compatible bilayer material systems for their realization using MEMS technology. Both bilayer systems leverage thermally-grown silicon dioxide as the principal stress-producing layer and a second material (either polyimide or aluminum) as the main structural layer. Arrays of buckled circular diaphragms, ranging in diameter from 100
μ m to 700μ m in 50μ m increments, were fabricated and their performances were compared to modeled and FEA-simulated results. In all cases, the diaphragms buckled when DRIE-released as expected, and their buckled experimental heights were within 9.1% of the theory and 1.8% of the FEA prediction. Interestingly, the smaller diameter structures exhibited a directional bias which we investigate and forecast using FEA. These bistable mechanical elements have the ability to serve as building blocks for no-power threshold-driven smart switches. New contributions to the field include: (a) introduction of a new bistable material system made from aluminum and compressive oxide, (b) investigation of diaphragm diameter size as it related to the phenomena of bistability versus non-bistability, (c) FEA analysis of the critical transition between bistability and non-bistability, and (d) introduction of the ‘dome factor’ term to describe dome quality. -
more » « less
Abstract Self‐sustainable energy generation represents a new frontier to significantly extend the lifetime and effectiveness of implantable biomedical devices. In this work, a piezoelectric energy harvester design is employed to utilize the bending of the lead of a cardiac pacemaker or defibrillator for generating electrical energy with minimal risk of interfering with cardiovascular functions. The proposed energy harvester combines flexible porous polyvinylidene fluoride–trifluoroethylene thin film with a buckled beam array design for potentially harvesting energy from cardiac motion. Systematic in vitro experimental evaluations are performed by considering complex parameters in practical implementations. Under various mechanical inputs and boundary conditions, the maximum electrical output of this energy harvester yields an open circuit voltage (peak to peak) of 4.5 V and a short circuit current (peak to peak) of 200 nA, and that energy is sufficient to self‐power a typical pacemaker for 1 d. A peak power output of 49 nW is delivered at an optimal resistor load of 50 MΩ. The scalability of the design is also discussed, and the reported results demonstrate the energy harvester's capability of providing significant electrical energy directly from the motions of pacemaker leads, suggesting a paradigm for biomedical energy harvesting in vivo.
-
more » « less
Abstract Piezoelectric transducers are widely employed in vibration control and energy harvesting. The effective electro-mechanical coupling of a piezoelectric system is related to the inherent capacitance of the piezoelectric transducer. It is known that passive vibration suppression through piezoelectric LC shunt can be enhanced with the integration of negative capacitance which however requires a power supply. This research focuses on the parametric investigation of a self-sustainable negative capacitance where the piezoelectric transducer is concurrently used in both vibration suppression and energy harvesting through LC shunt. The basic idea is to utilize the energy harvesting functionality of the piezoelectric transducer to aid the usage of negative capacitance in terms of power supply. Specifically, the power consumption and circuitry performance with respect to negative capacitance circuit design is analyzed thoroughly. Indeed, the net power generation is the difference between available power in the shunt circuit and the power consumption of the negative capacitance circuit. There exists complex tradeoffs between net power generation and the vibration suppression performance when we use different resistance values in the negative capacitance circuit. It is demonstrated through correlated analytical simulation and experimental study that the proper selection of the resistance values in the negative capacitance circuit can result in vibration suppression enhancement as well as improved net power generation, leading to a self-sustainable negative capacitance scheme.
-
more » « less
Abstract Interface stress between structural materials and thin film coatings has a significant influence on the resonant frequency of microelectromechanical system (MEMS) resonators. In this work, the axial stress on different types of buckled bridge MEMS resonator structures is controlled through the solid‐to‐solid phase transition of a VO2thin film coating. The devices have identical dimensions, but different buckling orientations and profiles due to the combined effect of overetching and residual thermal stress mismatch. Thermal actuation is used to tune the resonant frequency of the device, but the changes in frequency are found to be dependent on the type of buckling for the device. Thermal actuation is achieved by applying an electrical current to integrated heaters, or by uniform substrate heating. Bidirectional tunability is found when substrate heating is used, while Joule heating shows a monotonic change in frequency. This phenomenon can be attributed to the transition in boundary conditions, where the turning points are indicated by the prominent changes in buckling amplitude. In addition, devices with opposite buckling orientations exhibit different tuning behaviors which can be explained by different bending moments induced by beam stress interface modification.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1155/2019/6743676
