X. Chen
CUNY Advanced Science Research Center,
United States
Keywords: water-responsive materials, evaporation energy, silk, actuators
Summary:
In nature, plants have developed water-responsive (WR) materials that mechanically deform in response to changes in relative humidity. These WR materials can harness evaporation and convert it into forces or locomotion that drive plants’ essential tasks, such as pinecones that open and release pine seeds when the environment is dry. Several of these mechanically robust, yet flexible structures can actuate more powerfully than existing actuators and muscles and they hold promise as efficient actuators for energy harvesting, adaptive structures, and soft robotics. Our recent progress in biological WR materials has enabled the development of muscles with record-high performance. For example, we have developed a highly scalable method to modify silk’s secondary structures and dramatically increase regenerated Bombyx mori silk’s WR actuation energy density, surpassing those of all known natural muscles. These high-performance WR materials have led to the development of the evaporation energy harvesting devices that run autonomously when placed at a suitable air-water vapor interface. This allows for direct energy harvesting from naturally occurring or engineered water evaporation and subsequent conversion into mechanical energy or electricity. Such energy harvesting systems provide pioneering methods to harness the untapped energy source of natural evaporation.