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Triboelectric Energy-Harvesting Floor Tile
(2022-12-01)
Thainiramit, Panu
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Jayasvasti, Subhawat
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Yingyong, Phonexai
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Nandrakwang, Songmoung
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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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Evaluation of harvesting energy from pedestrians using piezoelectric floor tile energy harvester
(2021-11-01)
Yingyong, Phonexai
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Thainiramit, Panu
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Jayasvasti, Subhawat
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Thanach-Issarasak, Nicharas
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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.
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Technique for measuring power across high resistive load of triboelectric energy harvester
(2021-07-01)
Jayasvasti, Subhawat
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Thainiramit, Panu
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Yingyong, Phonexai
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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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Potential of Piezoelectric Floor Tile for Harvesting Energy from Human Footsteps
(2021-01-01)
Thanach-Issarasak, Nicharas
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Jayasvasti, Subhawat
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Yingyong, Phonexai
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Isarakorn, Don
Since the last decade, piezoelectric floor tile energy harvesters have been developed to convert wasted mechanical energy into usable electrical energy. Our team has also been developing and improving this kind of harvester, abbreviated as EHFT, for several years. One of the developmental problems was in reporting a realistic value of energy generated by EHFT because it depended heavily on many real-world factors. The objective of this study was to determine such realistic value by simulating those factors with a real-world traffic of 30 people entering a building. An EHFT together with proper electrical measurement devices were installed at the entrance of a building in King Mongkut's Institute of Technology, Thailand, and a group of 30 people were asked to step on it while entering the building. The value of the cumulative generated energy from the EHFT with those participants for a time duration of 600 s was found to be 450.26 mJ. This value was sufficiently high to constantly power a temperature sensor during a whole workday. Therefore, we are in the process of developing an automated Covid-19 detection station in which the temperature sensor will be powered by this EHFT.
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Impact-driven energy harvesting: Piezoelectric versus triboelectric energy harvesters
(2020-10-02)
Thainiramit, Panu
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Yingyong, Phonexai
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Isarakorn, Don
This work investigated the mechanical and electrical behaviors of piezoelectric and triboelectric energy harvesters (PEHs and TEHs, respectively) as potential devices for harvesting impact-driven energy. PEH and TEH test benches were designed and developed, aiming at harvesting low-frequency mechanical vibration generated by human activities, for example, a floor-tile energy harvester actuated by human footsteps. The electrical performance and behavior of these energy harvesters were evaluated and compared in terms of absolute energy and power densities that they provided and in terms of these energy and power densities normalized to unit material cost. Several aspects related to the design and development of PEHs and TEHs as the energy harvesting devices were investigated, covering the following topics: construction and mechanism of the energy harvesters; electrical characteristics of the fabricated piezoelectric and triboelectric materials; and characterization of the energy harvesters. At a 4 mm gap width between the cover plate and the stopper (the mechanical actuation components of both energy harvesters) and a cover plate pressing frequency of 2 Hz, PEH generated 27.64 mW, 1.90 mA, and 14.39 V across an optimal resistive load of 7.50 kΩ, while TEH generated 1.52 mW, 8.54 µA, and 177.91 V across an optimal resistive load of 21 MΩ. The power and energy densities of PEH (4.57 mW/cm3 and 475.13 µJ/cm3) were higher than those of TEH (0.50 mW/cm3, and 21.55 µJ/cm3). However, when the material cost is taken into account, TEH provided higher power and energy densities per unit cost. Hence, it has good potential for upscaling, and is considered well worth the investment. The advantages and disadvantages of PEH and TEH are also highlighted as main design factors.
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Energy harvesting for self-powered systems
(2020-07-01)
Nundrakwang, Songmoung
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Yingyong, Phonexai
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Isarakorn, Don
Harvesting energy from waste energy sources in ambient environmental is the accessible technology in the field of self-power electronic devices for high-efficiency energy due to the power consumption of modern electronic devices that are rapidly developed to microwatt, low-cost, lightweight, and small size. Since numerous research are investigated the technique for converting the ambient energy into useable electrical energy for practical application. Including light, thermal gradients, vibration or motion, and radio-frequency electromagnetic radiation, various forms of waste energy sources are proposed in this review. Their existing power density in the ambient environment is demonstrated. Moreover, the fundamental theory and the application of the energy harvesting devices are discussed as a foundation of the energy conversion technology for self-power electronic devices such as handheld, wearable, and portable devices.
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A Comparative Study of the Electrical Characteristics of Piezoelectric and Triboelectric Nanogenerators for Energy-Harvesting Floor Tiles
(2020-06-01)
Yingyong, Phonexai
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Thainiramit, Panu
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Nundrakwang, Songmoung
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Janphuang, Pattanaphong
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Isarakorn, Don
Piezoelectric and Triboelectric nanogenerators (PENG and TENG) have gained significant attention for use in self-powered electronics and sensing systems. They also have high potential to harvest energy from low-frequency vibration sources in the ambient environment. This paper investigated the performance and behavior of the two aforementioned nanogenerators based on energy-harvesting floor tiles by using a test bench to demonstrate the electrical characteristics output and comparing their power density output, energy density output, and other properties for characterization and scale-up in practical applications. The input used in the experiment varied the gap distance of the cover plate for the test bench with constant pneumatic pressure to excite the cover plate. The experimental results showed that the power density and energy density of PENG were higher than those of the TENG. The power density and energy density measured in 10 s under 2 Hz of input excitation of PENG and TENG at the gap width of 5 mm were 5773.35 μW/cm3, 1376.26 μJ/cm3 and 752.34 μW/cm3, 31.32 μJ/cm3, respectively. Due to their high output density, they enable promising possibilities to power small consumption electronics and sensing systems.
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Performance and Behavior Analysis of Single-Electrode Triboelectric Nanogenerator for Energy Harvesting Floor Tiles
(2020-06-01)
Yingyong, Phonexai
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Thainiramit, Panu
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Vittayakorn, Naratip
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Isarakorn, Don
A triboelectric nanogenerator (TENG) is a promising candidate for harvesting the wasted energy from the ambient environment and utilizing it as an independent power source for batteries used in wearable and portable devices as well as sensing systems. This paper investigated the performance and behavior of triboelectric energy harvesters based on energy harvesting floor tiles by applying different mechanical input parameters such as contact gap, velocity, and vibration frequency to characterize the electrical characteristics while maintaining the applied pressure of 600 kPa and temperature. The results revealed that massive air gap displacement tends to generate higher electrical output. This demonstrated that the device could generate 2294.14 μW of optimal power and 95.50 μJ of total energy in 10 s at the mechanical excited frequency of 2 Hz with a fixed gap displacement of 5 mm. Moreover, the output power is proportional to the velocity of the cover plate movement. In contrast, varying the relative humidity (%RH) showed that the TENG could generate high electrical output at low relative humidity. The proposed work demonstrates that the TENG can function as an energy-harvesting device from low-frequency mechanical vibration for energy harvesting floor tiles.
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Design and evaluation of double-stage energy harvesting floor tile
(2019-10-01)
Isarakorn, Don
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Jayasvasti, Subhawat
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Panthongsy, Phosy
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Janphuang, Pattanaphong
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Hamamoto, Kazuhiko
This paper introduces the design and characterization of a double-stage energy harvesting floor tile that uses a piezoelectric cantilever to generate electricity from human footsteps. A frequency up-conversion principle, in the form of an overshooting piezoelectric cantilever, plucked with a proof mass is utilized to increase energy conversion efficiency. The overshoot of the proof mass is implemented by a mechanical impact between a moving cover plate and a stopper to prevent damage to the plucked piezoelectric element. In an experiment, the piezoelectric cantilever of a floor tile prototype was excited by a pneumatic actuator that simulated human footsteps. The key parameters affecting the electrical power and energy outputs were investigated by actuating the prototype with a few kinds of excitation input. It was found that, when actuated by a single simulated footstep, the prototype was able to produce electrical power and energy in two stages. The cantilever resonated at a frequency of 14.08 Hz. The output electricity was directly proportional to the acceleration of the moving cover plate and the gap between the cover plate and the stopper. An average power of 0.82 mW and a total energy of 2.40 mJ were obtained at an acceleration of 0.93 g and a gap of 4 mm. The prototype had a simple structure and was able to operate over a wide range of frequencies.
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Performance and behavior analysis of piezoelectric energy harvesting floor tiles
(2019-07-01)
Panthongsy, Phosy
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Isarakorn, Don
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Hamamoto, Kazuhiko
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Janphuang, Pattanaphong
This paper presents the performance and behavior analysis of two unlike piezoelectric energy harvesting floor tiles in which they are functioned with different frequency up-conversion strategies to achieve the high energy conversion efficiency from low and variable-frequency vibration as the human footstep. One of such strategies is to convert the frequency of piezoelectric bimorph up through the magnetic interaction between a permanent magnet and an iron plate, while another one is achieved on that through the mechanical impact between a cover plate and a wall of the floor tile. Experimentally, the floor tiles having one piezoelectric bimorph inside of them are prototyped and then mounted to their individual input-exciting kit to investigate the energy harvesting performance. The input-exciting kits are employed to simulate the human footstep on floor tiles. The results show that the floor tile with frequency up-converting mechanism based on mechanical impact should be a better option for energy harvesting from human footstep due to the low-profile structure and good energy harvesting performance. Moreover, its operational way can result in long-lasting piezoelectric bimorph. When a cover plate is actuated to move down with the velocity of 54.13 mm/s and then released, the floor tile can produce the average power of 0.82 mW at load resistance approximately of 55.68 kΩ.

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