Swee Leong Kok | Universiti Teknikal Malaysia Melaka (original) (raw)

Papers by Swee Leong Kok

Piezoelectric materials have many desirable characteristics for use in vibration energy harvestin... more Piezoelectric materials have many desirable characteristics for use in vibration energy harvesting applications. They can produce relatively high output voltages (from a few to several tens of volts) for modest levels of vibration. Many piezoelectric-based generators use piezoceramic materials such as bulk lead zirconate titanate (PZT), which are attached to an elastic element (spring/beam) by using an adhesive.

Abstract Due to the fact that the ambient vibration sources are random and unpredictable, therefo... more Abstract Due to the fact that the ambient vibration sources are random and unpredictable, therefore a vibration based energy harvesting device is desirable to be able to operate at wider bandwidth in an envelop of frequency range to generate maximum electrical output. In this paper, various ambient vibration from household appliances, machineries, vehicle and moving vehicle were measured and investigated. The second part of the paper will discuss the strategies to harvest these ambient vibration sources.

Abstract Ambient vibration is one of the popular sources for energy harvesting due to its ubiquit... more Abstract Ambient vibration is one of the popular sources for energy harvesting due to its ubiquitous present in almost everywhere. For the past few years it has attracted many interests in the design and development of vibration based micro generators for low power electronic applications. The aim of this paper is to investigate on useful ambient vibration sources which would have great potential for the application of energy harvesting. Commonly the acceleration level of ambient vibration is low, in the range<; 1 g-level.

Abstract A free-standing thick-film cantilever sensor structure is presented. Such devices find u... more Abstract A free-standing thick-film cantilever sensor structure is presented. Such devices find use in applications such as vibration detection or energy harvesting. The structure was fabricated by screen printing layers of lead zirconate titanate between silver/palladium electrodes and co-firing the layers together with a carbon sacrificial layer (deposited underneath) in an air environment at a temperature of 850degC.

Research on energy harvesting from ambient vibration sources has been attracting tremendous atten... more Research on energy harvesting from ambient vibration sources has been attracting tremendous attention recently. Free-standing piezoelectric structures are among the devices used as the energy harvester. The structures are commonly fabricated by using thin-film technology. However, their electromechanical properties are typically lower than those of thick-film materials.

Combinations of conventional thick-film technology and sacrificial layer techniques were used to ... more Combinations of conventional thick-film technology and sacrificial layer techniques were used to fabricate free-standing structures, in the form of cantilever beams. By taking advantage of the different thermal expansion coefficients between silver/palladium (Ag/Pd) and piezoceramic Pb (Zr, Ti) O3, it was possible to fabricate a flat, but angled cantilever.

Abstract In this paper, free-standing structures in the form of cantilevers, fabricated by using ... more Abstract In this paper, free-standing structures in the form of cantilevers, fabricated by using a combination of conventional thick-film technology and sacrificial layer techniques, is proposed. These structures were designed to operate as energy harvesters at low-levels of ambient vibration and were characterised using a shaker table over a range of frequencies and acceleration levels.

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Piezoelectricity is the ability of certain crystals to generate a voltage when a corresponding me... more Piezoelectricity is the ability of certain crystals to generate a voltage when a corresponding mechanical stress is applied. The piezoelectric effect is reversible, where the shape of the piezoelectric crystals will deform proportional to externally applied voltage.

Electrical, Control …, Jan 1, 2011

Due to the fact that the ambient vibration sources are random and unpredictable, the design of en... more Due to the fact that the ambient vibration sources are random and unpredictable, the design of energy harvesters responding to multi-frequency is desirable. In this paper, an array lead zirconate titanate (PZT) thick-film cantilevers were designed and fabricated to demonstrate the possibility of harvesting vibration energy from different frequencies. Two configurations of multi-cantilever were fabricated in a form that elevated from the substrate as free-standing structures. One having six cantilevers of constant width but different lengths and another having five cantilevers of constant length but different widths. The experimental results show a magnitude of voltage at around 70 mV in a range of frequency between 220 Hz to 520 Hz which is in a good agreement with simulation results.

… Electronics, 2000. Proceedings …, Jan 1, 2000

Abstract - An optical network device that formed by three cascaded directional couplers is discus... more Abstract - An optical network device that formed by three cascaded directional couplers is discussed in this paper. Wavelengths of 1535.04nm, 1545.32nm, 1555.75nm and 1565.50nm from ITU channels are the sources of input signal that are used to study in the way they propagate ...

Measurement Science and …, Jan 1, 2009

Ultrasonics Symposium (IUS), …, Jan 1, 2009

… Conference, Jan 1, 2008

Free-standing thick-film cantilevers have the potential to be used as micro-generators as well as... more Free-standing thick-film cantilevers have the potential to be used as micro-generators as well as self-generating resonant sensors. Earlier versions of free-standing devices were implemented by fabricating in the form of multilayer structures. Instead of structures with a plate of PZT ...