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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

Scaling up hydration-driven nanoscale energy conversion.(a) Water confined to nanoscale cavities, conduits and surfaces within hygroscopic materials can induce large pressures in response to changing relative humidity. (b) A scanning electron microscopy image of the cross-section of a B. subtilis spore. Spores exhibit strong mechanical response to changing relative humidity18 by absorbing and releasing moisture. (c) A false-coloured s.e.m. picture of spores (grey) deposited on an 8-micrometre-thick polyimide tape (yellow). (d) The spore-coated films bend and straighten in response to changing relative humidity. (e) Patterning equally spaced spore layers on both sides of the plastic tape creates linearly expanding and contracting structures. (f) Stacking the tapes in e with air gaps between them results in a material that can be scaled in two dimensions without compromising hydration/dehydration kinetics. (g) A shutter mechanism can create oscillations. (h) Photo of a device that exhibit self-starting oscillatory movement when placed above water. (i) Rotary motion can lead to cyclical changes of relative humidity experienced by the spores. The increased curvature on the dry side shifts the centre of mass of the entire structure away from the axis of rotation and creates torque. (j) Photo of a device whose continuous rotation is powered by evaporation from the wet paper within the device.
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f1: Scaling up hydration-driven nanoscale energy conversion.(a) Water confined to nanoscale cavities, conduits and surfaces within hygroscopic materials can induce large pressures in response to changing relative humidity. (b) A scanning electron microscopy image of the cross-section of a B. subtilis spore. Spores exhibit strong mechanical response to changing relative humidity18 by absorbing and releasing moisture. (c) A false-coloured s.e.m. picture of spores (grey) deposited on an 8-micrometre-thick polyimide tape (yellow). (d) The spore-coated films bend and straighten in response to changing relative humidity. (e) Patterning equally spaced spore layers on both sides of the plastic tape creates linearly expanding and contracting structures. (f) Stacking the tapes in e with air gaps between them results in a material that can be scaled in two dimensions without compromising hydration/dehydration kinetics. (g) A shutter mechanism can create oscillations. (h) Photo of a device that exhibit self-starting oscillatory movement when placed above water. (i) Rotary motion can lead to cyclical changes of relative humidity experienced by the spores. The increased curvature on the dry side shifts the centre of mass of the entire structure away from the axis of rotation and creates torque. (j) Photo of a device whose continuous rotation is powered by evaporation from the wet paper within the device.

Mentions: While evaporation carries a significant amount of energy2223, it involves a slow rate of water transfer that limits the relative expansion and contraction of hygroscopic materials. Because the relative volume of the absorbed and released water is small, the pressure change generated during this process has to be large for efficient energy conversion. Water confined to nanoscale cavities within hygroscopic materials (Fig. 1a) can induce large pressures in response to changing relative humidity242526; however, these nanostructures also limit the transport kinetics of water. Simply scaling up the dimensions of hygroscopic materials would not increase power, and may even lead to a decrease, because the time scale of wetting and drying typically depend on the square of the travel distance of water19.


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)

Scaling up hydration-driven nanoscale energy conversion.(a) Water confined to nanoscale cavities, conduits and surfaces within hygroscopic materials can induce large pressures in response to changing relative humidity. (b) A scanning electron microscopy image of the cross-section of a B. subtilis spore. Spores exhibit strong mechanical response to changing relative humidity18 by absorbing and releasing moisture. (c) A false-coloured s.e.m. picture of spores (grey) deposited on an 8-micrometre-thick polyimide tape (yellow). (d) The spore-coated films bend and straighten in response to changing relative humidity. (e) Patterning equally spaced spore layers on both sides of the plastic tape creates linearly expanding and contracting structures. (f) Stacking the tapes in e with air gaps between them results in a material that can be scaled in two dimensions without compromising hydration/dehydration kinetics. (g) A shutter mechanism can create oscillations. (h) Photo of a device that exhibit self-starting oscillatory movement when placed above water. (i) Rotary motion can lead to cyclical changes of relative humidity experienced by the spores. The increased curvature on the dry side shifts the centre of mass of the entire structure away from the axis of rotation and creates torque. (j) Photo of a device whose continuous rotation is powered by evaporation from the wet paper within the device.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Scaling up hydration-driven nanoscale energy conversion.(a) Water confined to nanoscale cavities, conduits and surfaces within hygroscopic materials can induce large pressures in response to changing relative humidity. (b) A scanning electron microscopy image of the cross-section of a B. subtilis spore. Spores exhibit strong mechanical response to changing relative humidity18 by absorbing and releasing moisture. (c) A false-coloured s.e.m. picture of spores (grey) deposited on an 8-micrometre-thick polyimide tape (yellow). (d) The spore-coated films bend and straighten in response to changing relative humidity. (e) Patterning equally spaced spore layers on both sides of the plastic tape creates linearly expanding and contracting structures. (f) Stacking the tapes in e with air gaps between them results in a material that can be scaled in two dimensions without compromising hydration/dehydration kinetics. (g) A shutter mechanism can create oscillations. (h) Photo of a device that exhibit self-starting oscillatory movement when placed above water. (i) Rotary motion can lead to cyclical changes of relative humidity experienced by the spores. The increased curvature on the dry side shifts the centre of mass of the entire structure away from the axis of rotation and creates torque. (j) Photo of a device whose continuous rotation is powered by evaporation from the wet paper within the device.
Mentions: While evaporation carries a significant amount of energy2223, it involves a slow rate of water transfer that limits the relative expansion and contraction of hygroscopic materials. Because the relative volume of the absorbed and released water is small, the pressure change generated during this process has to be large for efficient energy conversion. Water confined to nanoscale cavities within hygroscopic materials (Fig. 1a) can induce large pressures in response to changing relative humidity242526; however, these nanostructures also limit the transport kinetics of water. Simply scaling up the dimensions of hygroscopic materials would not increase power, and may even lead to a decrease, because the time scale of wetting and drying typically depend on the square of the travel distance of water19.

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