Bio-inspired Water-responsive Materials for Energy Conversion and Actuators
Abstract
To support our long-term goal of investigating and developing evaporation energy harvesting techniques that we have pioneered, this proposal primarily focuses on identifying the fundamental mechanisms of materials??? powerful water-responsive behaviors, which will allow us to bring the evaporation energy harvesting technique one step closer to practical applications, and to developthe next generation actuators. We have found that the energy density of spore???s water-responsive actuation is significantly higher than that of all existing actuator materials and artificial muscles. We hypothesize that a dehydration process can induce a large negative pressure in water confined in nanoscale structures in spores. This negative pressure pulls the surfaces of these nanoscale structures and stores elastic potential energy inside the material. This energy storage process stops when the chemical potential reaches an equilibrium state, or when cavitation forms in nanoconfined water. The stored elastic potential energy will be then released during a hydration process where nanoscale structures restore to their normal positions. Peptidoglycan, which is believed to be the dominant component of spores??? water-responsive behaviors, may have anoptimum nanoporous structure, stiffness, and wettability of pores that helps water to maintain a huge negative pressure, as well as to store a large elastic potential energy. TO VALIDATE OUR HYPOTHESIS, WE PLAN TO 1) characterize water-responsive properties of peptidoglycan from spores, 2) understand the correlation of bacterial peptidoglycan???s waterresponsive behaviors with its mechanical and chemical properties, and 3) test water-responsive behaviors of nanofabricated structures. We will extract peptidoglycan from both spores andbacterial species, and study their water-responsive strain, speed, and energy densities by using the atomic force microscope (AFM) that we previously customized. By using advanced imaging techniques at the CUNY Advanced Science Research Center, we will study peptidoglycan???s nanoporous size, stiffness, wettability, as well as its water-responsive properties. In addition, weplan to fabricate submicron and nano scale trenches, forming nanochannels whose vertical sidewalls are two parallel islands that can bend inwards. By tuning their separation distances, stiffness, and wettability, we expect to measure the negative pressure and the stored elastic potential energy indicated by using AFM, which will then be compared to that of peptidoglycan to further validate the hypothesis. IMPACT: The proposed research could lead to 1) the discovery and development of more powerful actuator materials that would provide new opportunities for underwater actuations, robots, submerged vehicles, and exoskeletons. The actuation pressure of these water-responsive materials could potentially exceed 200 MPa, which is sufficient to operate against significant water pressure even in the deepest part of Earth???s oceans (~110 MPa). The proposed research could eventually lead to 2) evaporation-driven generators that would be deployable as floating harvesters on anybody of fresh or saltwater. This new type of energy generation could be used to power maritime sensing, mobile ocean surveillance systems, research facilities, Navy surface ships, and even Navy bases. The proposed research on nanoconfined water in biomaterials could provide 3) an insight into the important role of nanoscale water in biological processes. Such enhanced understandingof nanoconfined water could contribute to the development of bioinspired and biomimetic devicesor materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 26, 2018
- Source ID
- N000141812492
Entities
People
- Xi Chen
Organizations
- Office of Naval Research
- Research Foundation of The City University of New York
- United States Navy