Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators.
Materials that respond mechanically to external chemical stimuli have applications in biomedical devices, adaptive architectural systems, robotics and energy harvesting. Inspired by biological systems, stimuli-responsive materials have been created that can oscillate, transport fluid, provide homeostasis and undergo complex changes in shape. However, the effectiveness of synthetic stimuli-responsive materials in generating work is limited when compared with mechanical actuators. Here, we show that the mechanical response of Bacillus spores to water gradients exhibits an energy density of more than 10 MJ m(-3), which is two orders of magnitude higher than synthetic water-responsive materials. We also identified mutations that can approximately double the energy density of the spores and found that they can self-assemble into dense, submicrometre-thick monolayers on substrates such as silicon microcantilevers and elastomer sheets, creating bio-hybrid hygromorph actuators. To illustrate the potential applications of the spores, we used them to build an energy-harvesting device that can remotely generate electrical power from an evaporating body of water.
Department of Biological Sciences and Department of Physics, Columbia University, New York, New York 10027, USA.
Xi
X
Chen
1] School of Engineering and Applied Sciences, Department of Physics, Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA [2] Kavli Institute for Nanobio Science and Technology, Harvard University, Cambridge, Massachusetts 02138, USA [3] Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts 02115, USA.
L
L
Mahadevan
Department of Microbiology and Immunology, Loyola University Medical Center, 2160 S. First Avenue, Maywood, Illinois 60153, USA.
Adam
A
Driks
1] Department of Biological Sciences and Department of Physics, Columbia University, New York, New York 10027, USA [2] Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts 02115, USA.
Ozgur
0000000327662816
O
Sahin
D001407:Bacillus / Q000166:cytology / Q000502:physiology; D001674:Bioelectric Energy Sources / Q000382:microbiology*; D049329:Nanostructures / Q000648:ultrastructure*; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods; D013170:Spores / Q000166:cytology / Q000502:physiology