title: Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators.
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.
authors.affiliation: Department of Biological Sciences, Columbia University, New York 10027, New York, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Biological Sciences, Columbia University, New York 10027, New York, USA.
authors.forename: Davis
authors.initials: D
authors.lastname: Goodnight
authors.affiliation: Department of Physics, Columbia University, New York 10027, New York, USA.
authors.forename: Zhenghan
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Department of Chemical Engineering, Columbia University, New York 10027, New York, USA.
authors.forename: Ahmet H
authors.initials: AH
authors.lastname: Cavusoglu
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York 10027, New York, USA.
authors.forename: Nina
authors.initials: N
authors.lastname: Sabharwal
authors.affiliation: Department of Biological Sciences, Columbia University, New York 10027, New York, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: DeLay
authors.affiliation: Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, USA.
authors.forename: Adam
authors.initials: A
authors.lastname: Driks
authors.affiliation: Department of Biological Sciences, Columbia University, New York 10027, New York, USA.|Department of Physics, Columbia University, New York 10027, New York, USA.
authors.forename: Ozgur
authors.initials: O
authors.lastname: Sahin