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Bubbler: A Novel Ultra-High Power Density Energy Harvesting Method Based on Reverse Electrowetting.

Hsu TH, Manakasettharn S, Taylor JA, Krupenkin T - Sci Rep (2015)

Bottom Line: We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics.Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alone.This energy conversion approach is particularly well suited for energy harvesting applications and can enable effective coupling to a broad array of mechanical systems including such ubiquitous but difficult to utilize low-frequency energy sources as human and machine motion.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University of Wisconsin-Madison, 1513 UniversityAvenue, Mechanical Engineering Building Room 2238, Madison, WI, 53706, USA.

ABSTRACT
We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics. The method combines previously demonstrated reverse electrowetting on dielectric (REWOD) phenomenon with the fast self-oscillating process of bubble growth and collapse. Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alone. This energy conversion approach is particularly well suited for energy harvesting applications and can enable effective coupling to a broad array of mechanical systems including such ubiquitous but difficult to utilize low-frequency energy sources as human and machine motion. The method can be scaled from a single micro cell with 10(-6) W output to power cell arrays with a total power output in excess of 10 W. This makes the fabrication of small light-weight energy harvesting devices capable of producing a wide range of power outputs feasible.

No MeSH data available.


Related in: MedlinePlus

Experimental investigation of the bubble growth and collapse process.The schematics of the experiment is shown on the left, and the actual image of the light source as seen by the high-speed camera positioned at the light detector spot is shown on the right. The black central spot in the actual image indicates the tube connecting to the pressurized dielectric fluid. Water was used as a dielectric fluid in this experiment. (a) indicates the initial stage of bubble growth, (b) final stage of bubble growth, and (c) bubble collapse.
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f6: Experimental investigation of the bubble growth and collapse process.The schematics of the experiment is shown on the left, and the actual image of the light source as seen by the high-speed camera positioned at the light detector spot is shown on the right. The black central spot in the actual image indicates the tube connecting to the pressurized dielectric fluid. Water was used as a dielectric fluid in this experiment. (a) indicates the initial stage of bubble growth, (b) final stage of bubble growth, and (c) bubble collapse.

Mentions: The predictions of the CFD model were supported by the experimental measurements of the intensity of the light penetrating through the bubbler assembly. This simple method, the details of which are illustrated in Fig. 6, allows experimental observation of the bubbler oscillation dynamics at high frequencies (see Supplementary Video 3). The observed light intensity is expected to scale linearly with the area of contact between the bubble and the membrane, as shown in Fig. 6(a–c). The typical result for the air bubble self-oscillations are shown in Fig. 4(f). As one can see the variation of the relative light intensity with time is in good qualitative agreement with the theoretical curve for the time dependence of the footprint area of the bubble, as shown in Fig. 4(e). The experimentally obtained peaks of the light intensity have noticeable variability, which, in our opinion, can be attributed mainly to the random deviation of the bubble footprint shape from the ideal circle, caused by the occasional pining of the mercury contact line by the imperfections of the electrode surface. These deviations produce random variations in the bubble footprint area, which, in turn, result in the variation of the registered light intensity. In addition to that the model setup invariably includes some simplifying assumptions. In particular the calculated results for the bubble footprint area shown in Fig. 4(e) are based on the assumption that the air pressure inside the bubbler chip is equal to the air pressure in the air supply line, which might not be exactly true. This might cause some additional difference between the model and the experimental results.


Bubbler: A Novel Ultra-High Power Density Energy Harvesting Method Based on Reverse Electrowetting.

Hsu TH, Manakasettharn S, Taylor JA, Krupenkin T - Sci Rep (2015)

Experimental investigation of the bubble growth and collapse process.The schematics of the experiment is shown on the left, and the actual image of the light source as seen by the high-speed camera positioned at the light detector spot is shown on the right. The black central spot in the actual image indicates the tube connecting to the pressurized dielectric fluid. Water was used as a dielectric fluid in this experiment. (a) indicates the initial stage of bubble growth, (b) final stage of bubble growth, and (c) bubble collapse.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645099&req=5

f6: Experimental investigation of the bubble growth and collapse process.The schematics of the experiment is shown on the left, and the actual image of the light source as seen by the high-speed camera positioned at the light detector spot is shown on the right. The black central spot in the actual image indicates the tube connecting to the pressurized dielectric fluid. Water was used as a dielectric fluid in this experiment. (a) indicates the initial stage of bubble growth, (b) final stage of bubble growth, and (c) bubble collapse.
Mentions: The predictions of the CFD model were supported by the experimental measurements of the intensity of the light penetrating through the bubbler assembly. This simple method, the details of which are illustrated in Fig. 6, allows experimental observation of the bubbler oscillation dynamics at high frequencies (see Supplementary Video 3). The observed light intensity is expected to scale linearly with the area of contact between the bubble and the membrane, as shown in Fig. 6(a–c). The typical result for the air bubble self-oscillations are shown in Fig. 4(f). As one can see the variation of the relative light intensity with time is in good qualitative agreement with the theoretical curve for the time dependence of the footprint area of the bubble, as shown in Fig. 4(e). The experimentally obtained peaks of the light intensity have noticeable variability, which, in our opinion, can be attributed mainly to the random deviation of the bubble footprint shape from the ideal circle, caused by the occasional pining of the mercury contact line by the imperfections of the electrode surface. These deviations produce random variations in the bubble footprint area, which, in turn, result in the variation of the registered light intensity. In addition to that the model setup invariably includes some simplifying assumptions. In particular the calculated results for the bubble footprint area shown in Fig. 4(e) are based on the assumption that the air pressure inside the bubbler chip is equal to the air pressure in the air supply line, which might not be exactly true. This might cause some additional difference between the model and the experimental results.

Bottom Line: We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics.Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alone.This energy conversion approach is particularly well suited for energy harvesting applications and can enable effective coupling to a broad array of mechanical systems including such ubiquitous but difficult to utilize low-frequency energy sources as human and machine motion.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, University of Wisconsin-Madison, 1513 UniversityAvenue, Mechanical Engineering Building Room 2238, Madison, WI, 53706, USA.

ABSTRACT
We have proposed and successfully demonstrated a novel approach to direct conversion of mechanical energy into electrical energy using microfluidics. The method combines previously demonstrated reverse electrowetting on dielectric (REWOD) phenomenon with the fast self-oscillating process of bubble growth and collapse. Fast bubble dynamics, used in conjunction with REWOD, provides a possibility to increase the generated power density by over an order of magnitude, as compared to the REWOD alone. This energy conversion approach is particularly well suited for energy harvesting applications and can enable effective coupling to a broad array of mechanical systems including such ubiquitous but difficult to utilize low-frequency energy sources as human and machine motion. The method can be scaled from a single micro cell with 10(-6) W output to power cell arrays with a total power output in excess of 10 W. This makes the fabrication of small light-weight energy harvesting devices capable of producing a wide range of power outputs feasible.

No MeSH data available.


Related in: MedlinePlus