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Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators.

Chen X, Goodnight D, Gao Z, Cavusoglu AH, Sabharwal N, DeLay M, Driks A, Sahin O - Nat Commun (2015)

Bottom Line: These engines start and run autonomously when placed at air-water interfaces.Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates.Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Columbia University, New York 10027, New York, USA.

ABSTRACT
Evaporation is a ubiquitous phenomenon in the natural environment and a dominant form of energy transfer in the Earth's climate. Engineered systems rarely, if ever, use evaporation as a source of energy, despite myriad examples of such adaptations in the biological world. Here, we report evaporation-driven engines that can power common tasks like locomotion and electricity generation. These engines start and run autonomously when placed at air-water interfaces. They generate rotary and piston-like linear motion using specially designed, biologically based artificial muscles responsive to moisture fluctuations. Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates. Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.

No MeSH data available.


Related in: MedlinePlus

The evaporation-driven oscillatory engine.(a) The oscillator comprises horizontally placed HYDRAs coupled to a load spring and shutters that control permeation of moisture. Shutters are connected to a beam that is compressed beyond its buckling limit so that it has two stable configurations. (b) As the beam switches its position due to the force exerted by HYDRAs, the shutters open and close and alter the relative humidity of the chamber. (c) Picture of HYDRAs assembled in parallel pulling onto load springs. (d) Four stages of the oscillatory motion: (Stage I) When the shutters are closed, the relative humidity of the chamber increases, causing HYDRAs to expand. (Stage II) As HYDRAs expand towards the right, they force the buckled beam to switch its position. (Stage III) Opening of the shutters let the relative humidity of the chamber recede, causing HYDRAs to contract. The cycle is completed when contracting HYDRAs pull the buckled beam and force it to switch back to the left configuration (stage IV), which then closes the shutters and brings the system back to stage I. (e) Average period of oscillations as a function of water surface temperature. Markers indicate the average data values with error bars showing the s.d. calculated from three measurements. (f) Picture of the oscillator connected to an electromagnetic generator. The inset photo of the LEDs is taken during the operation. (g,h) Voltage and power measured across a load resistor of 100 kΩ. Scale bar, 2 cm.
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f3: The evaporation-driven oscillatory engine.(a) The oscillator comprises horizontally placed HYDRAs coupled to a load spring and shutters that control permeation of moisture. Shutters are connected to a beam that is compressed beyond its buckling limit so that it has two stable configurations. (b) As the beam switches its position due to the force exerted by HYDRAs, the shutters open and close and alter the relative humidity of the chamber. (c) Picture of HYDRAs assembled in parallel pulling onto load springs. (d) Four stages of the oscillatory motion: (Stage I) When the shutters are closed, the relative humidity of the chamber increases, causing HYDRAs to expand. (Stage II) As HYDRAs expand towards the right, they force the buckled beam to switch its position. (Stage III) Opening of the shutters let the relative humidity of the chamber recede, causing HYDRAs to contract. The cycle is completed when contracting HYDRAs pull the buckled beam and force it to switch back to the left configuration (stage IV), which then closes the shutters and brings the system back to stage I. (e) Average period of oscillations as a function of water surface temperature. Markers indicate the average data values with error bars showing the s.d. calculated from three measurements. (f) Picture of the oscillator connected to an electromagnetic generator. The inset photo of the LEDs is taken during the operation. (g,h) Voltage and power measured across a load resistor of 100 kΩ. Scale bar, 2 cm.

Mentions: Using HYDRAs, we have created oscillatory devices that allow and block evaporation in a cyclical fashion, so that energy can be continuously extracted from evaporation. While hygroscopic materials can exhibit spontaneous oscillatory motion due to turbulence or geometric nonlinearities1215, these movements are difficult to control and use in devices. To induce oscillations deliberately, we took advantage of the oscillator designs commonly used in electrical circuits. One particularly robust design is a relaxation oscillator that relies on a bistable circuit element (for example, a Schmitt trigger31) that is held under feedback control. The relaxation oscillator circuit repeatedly switches between two internal states. The basic architecture of our hygro-mechanical oscillator is designed in analogy with this relaxation oscillator. Figure 3a–d describes how HYDRAs coupled to a buckling beam and a shutter mechanism form a relaxation oscillator.


Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators.

Chen X, Goodnight D, Gao Z, Cavusoglu AH, Sabharwal N, DeLay M, Driks A, Sahin O - Nat Commun (2015)

The evaporation-driven oscillatory engine.(a) The oscillator comprises horizontally placed HYDRAs coupled to a load spring and shutters that control permeation of moisture. Shutters are connected to a beam that is compressed beyond its buckling limit so that it has two stable configurations. (b) As the beam switches its position due to the force exerted by HYDRAs, the shutters open and close and alter the relative humidity of the chamber. (c) Picture of HYDRAs assembled in parallel pulling onto load springs. (d) Four stages of the oscillatory motion: (Stage I) When the shutters are closed, the relative humidity of the chamber increases, causing HYDRAs to expand. (Stage II) As HYDRAs expand towards the right, they force the buckled beam to switch its position. (Stage III) Opening of the shutters let the relative humidity of the chamber recede, causing HYDRAs to contract. The cycle is completed when contracting HYDRAs pull the buckled beam and force it to switch back to the left configuration (stage IV), which then closes the shutters and brings the system back to stage I. (e) Average period of oscillations as a function of water surface temperature. Markers indicate the average data values with error bars showing the s.d. calculated from three measurements. (f) Picture of the oscillator connected to an electromagnetic generator. The inset photo of the LEDs is taken during the operation. (g,h) Voltage and power measured across a load resistor of 100 kΩ. Scale bar, 2 cm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490384&req=5

f3: The evaporation-driven oscillatory engine.(a) The oscillator comprises horizontally placed HYDRAs coupled to a load spring and shutters that control permeation of moisture. Shutters are connected to a beam that is compressed beyond its buckling limit so that it has two stable configurations. (b) As the beam switches its position due to the force exerted by HYDRAs, the shutters open and close and alter the relative humidity of the chamber. (c) Picture of HYDRAs assembled in parallel pulling onto load springs. (d) Four stages of the oscillatory motion: (Stage I) When the shutters are closed, the relative humidity of the chamber increases, causing HYDRAs to expand. (Stage II) As HYDRAs expand towards the right, they force the buckled beam to switch its position. (Stage III) Opening of the shutters let the relative humidity of the chamber recede, causing HYDRAs to contract. The cycle is completed when contracting HYDRAs pull the buckled beam and force it to switch back to the left configuration (stage IV), which then closes the shutters and brings the system back to stage I. (e) Average period of oscillations as a function of water surface temperature. Markers indicate the average data values with error bars showing the s.d. calculated from three measurements. (f) Picture of the oscillator connected to an electromagnetic generator. The inset photo of the LEDs is taken during the operation. (g,h) Voltage and power measured across a load resistor of 100 kΩ. Scale bar, 2 cm.
Mentions: Using HYDRAs, we have created oscillatory devices that allow and block evaporation in a cyclical fashion, so that energy can be continuously extracted from evaporation. While hygroscopic materials can exhibit spontaneous oscillatory motion due to turbulence or geometric nonlinearities1215, these movements are difficult to control and use in devices. To induce oscillations deliberately, we took advantage of the oscillator designs commonly used in electrical circuits. One particularly robust design is a relaxation oscillator that relies on a bistable circuit element (for example, a Schmitt trigger31) that is held under feedback control. The relaxation oscillator circuit repeatedly switches between two internal states. The basic architecture of our hygro-mechanical oscillator is designed in analogy with this relaxation oscillator. Figure 3a–d describes how HYDRAs coupled to a buckling beam and a shutter mechanism form a relaxation oscillator.

Bottom Line: These engines start and run autonomously when placed at air-water interfaces.Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates.Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Columbia University, New York 10027, New York, USA.

ABSTRACT
Evaporation is a ubiquitous phenomenon in the natural environment and a dominant form of energy transfer in the Earth's climate. Engineered systems rarely, if ever, use evaporation as a source of energy, despite myriad examples of such adaptations in the biological world. Here, we report evaporation-driven engines that can power common tasks like locomotion and electricity generation. These engines start and run autonomously when placed at air-water interfaces. They generate rotary and piston-like linear motion using specially designed, biologically based artificial muscles responsive to moisture fluctuations. Using these engines, we demonstrate an electricity generator that rests on water while harvesting its evaporation to power a light source, and a miniature car (weighing 0.1 kg) that moves forward as the water in the car evaporates. Evaporation-driven engines may find applications in powering robotic systems, sensors, devices and machinery that function in the natural environment.

No MeSH data available.


Related in: MedlinePlus