Jayasvasti, Subhawat

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Jayasvasti, Subhawat
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subhawat.ja@kmitl.ac.th

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    Item type:Publication,
    Technique for measuring power across high resistive load of triboelectric energy harvester
    (2021-07-01)
    Jayasvasti, Subhawat
    ;
    Thainiramit, Panu
    ;
    Yingyong, Phonexai
    ;
    Isarakorn, Don
    This paper proposed a more-accurate-than-conventional measurement technique for determining electrical power across exceptionally high-impedance of triboelectric energy harvester (TEH). The key idea of this proposed technique was to measure the voltage across an introduced, parallelly-connected resistor divider to the oscilloscope instead of the voltage across the harvester. An experiment was set up to verify the measurement accuracy performance of this technique against the ideal theoretical values. The maximum percentage error found was only 2.30%, while the conventional measurement technique could not be used to measure voltage across high impedance TEH at all because the readings were not accurate, i.e., the measurement error would be at least over 10%. Therefore, we concluded that this proposed technique should always be used instead of the conventional measurement technique for power measurement of any TEH. A suggestion that we would like to offer to researchers investigating or developing a TEH is that, in using our measurement technique, a good starting point for a load to probe resistance ratio is 1:10, a ratio that worked well for our TEH test bench that we developed.
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    Item type:Publication,
    Triboelectric Energy-Harvesting Floor Tile
    (2022-12-01)
    Thainiramit, Panu
    ;
    Jayasvasti, Subhawat
    ;
    Yingyong, Phonexai
    ;
    Nandrakwang, Songmoung
    ;
    Isarakorn, Don
    The aim of this study was to investigate the real-world electrical parameters that strongly affected the performance of a triboelectric energy-harvesting floor tile design: triboelectric material thickness, cover plate displacement distance or gap width, and cover plate pressing frequency, so that real-world specifications of the harvesting floor tile can be accurately specified. The structure of the designed triboelectric energy harvester, with readily available polytetrafluoroethylene (PTFE) film and aluminum foil, was simple and hence easy to fabricate, and the material cost was low. A square wave was used to simulate the pressing frequency on the test bench’s cover plate. The results showed that the voltage and current were proportional to the gap width, and the thinner the triboelectric layer thickness, the higher the output voltage and current. A test bench with a 0.2 mm thick PTFE triboelectric layer generated the highest energy output. In a later experiment, a triboelectric energy-harvesting floor tile (TEHFT) prototype was constructed with 0.1 and 0.2 mm thick PTFE layers. We found that at 2 Hz stepping frequency and 0.1 mm PTFE thickness, the optimal load and cumulative energy of the TEHFT were 0.8 MΩ and 3.81 mJ, respectively, while with 0.2 mm PTFE thickness, these two parameters were 1.1 MΩ and 7.69 mJ, respectively. The TEHFT with 0.2 mm thick PTFE layer was able to illuminate a series of 100 to 150 LEDs, sufficient power to drive small electronics and sensor nodes. This discovery provides important data on the structure, material, and contact surface area of a TEHFT that can be adjusted to suit specific requirements of a special function triboelectric energy harvester.
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    Item type:Publication,
    Evaluation of harvesting energy from pedestrians using piezoelectric floor tile energy harvester
    (2021-11-01)
    Yingyong, Phonexai
    ;
    Thainiramit, Panu
    ;
    Jayasvasti, Subhawat
    ;
    Thanach-Issarasak, Nicharas
    ;
    Isarakorn, Don
    This study determined the influences of several pedestrian parameters on the amount of energy harvested by a piezoelectric energy harvesting floor tile (EHFT), for the goal of providing a realistic harvested energy specification for an application in a certain pedestrian environment. Experiments were conducts to measure the original harvested energy in a laboratory and the harvested energy under a variety of pedestrian parameter values. The main outcomes were the following: the original, unadjusted harvested energy provided by one pedestrian step obtained in the laboratory was 35 mW<inf>rms</inf>; when ten people, weighing less than 50 kg or over 70 kg, stepped on the floor tile, the harvested energy was about 11.0 mJ and 32.0 mJ, respectively; When 30 people walked or ran over it without any fixed pattern, the harvested energy was about 289.0 mJ and 736.9 mJ, respectively; when 30 people walking in a row, separated by a gap of 0.5, 1, and 1.5 m, walking over the tile one by one, the stored energy was 401.0 mJ, 406.0 mJ, and 452.0 mJ, respectively. To conclude, two pedestrian parameters affected the harvested energy strongly pedestrian body weight and pace (walking or running), but pedestrian density did not affect the harvested energy of our developed EHFT strongly. Therefore, in an adjustment of a laboratory-obtained harvested energy into a realistic specification, the influences of those two pedestrian parameters had to be included, while pedestrian density could be ignored. These findings should be directly useful to new researchers and developers in their effort to formulate a realistic harvested energy specification for their developed EHFT.