Self-regulating Surfaces that Mitigate Detrimental Changes in Marine Conditions
Abstract
Approved for Public Release-Research Problem and objective. To counteract the damaging effects of environmental changes in the ocean, we will develop multi-functional, dynamic surfaces with the unique ability to harness unfavorable conditions, triggering collective movements that directly mitigate the effects of the triggering stimuli. Inspired by the dynamic functionality of hair-like marine cilia, our prototype materials will integrate flexible micro- to macro-scale posts within a stimuli-responsive gel. This material will dynamically respond to physico-chemical changes in fluids by generating mechanical forces that initiate cooperative behavior, especially for high flow environments. For example, increases in temperature can drive the gel to shrink or expand, and thus spontaneously move the embedded fibers; the fibers# motion, in turn, mixes different fluid layers, redistributes the thermal variations, and thereby mitigates the detrimental environmental change. While such feedback between cilia and their environment enables self-regulation, researchers rarely design synthetic surfaces with cooperative motion of structural elements, missing opportunities to leverage biomimetic mechanisms that could enhance resilience in marine environments. Our proposed research aims to address these shortcomings.--Technical Approaches. We build on work by Aizenberg in creating a powerful adaptive materials platform, so-called HAIRS (Hydrogel-Actuated Integrated Responsive Systems), in which nano- to micro-scale posts embedded in a stimuli-responsive hydrogel are activated into motion by changes in the gel volume. Using this system as a foundation, Balazs and Aizenberg will design new responsive gel/posts materials that undergo self-oscillations or actively hinder biofouling layers. Balazs will develop computational models to a priori predict the systems# responsive behavior under different flow conditions. Wangpraseurt will employ advanced 3D printing techniques to fabricate high-aspect-ratio polymeric fibers at the decimeter scale, with a modular design that allows these structures to be assembled to cover larger areas up to the meter scale. Aizenberg and Wangpraseurt will evaluate the effectiveness of these large structures in reducing fouling and/or promoting the growth of selective beneficial organisms, such as corals. Coming full circle, Wangpraseurt will conduct comparative microenvironmental observations on coral cilia as a biological analogue system to HAIRS, which will then be used to inform the modeling efforts of Balazs and the rational design of polymeric fibers by Aizenberg.--Outcomes. At the end of the three-year period, we will deliver multifunctional surfaces that alter their form and function to achieve control over natural variations of marine external stimuli. Specifically, our deliverables include: (1) high-aspect-ratio synthetic cilial structures ranging from decimeter-to-meter scale; (2) robust testing methods to evaluate the dynamic modulation of stimuli both in the lab and in situ; and (3) comprehensive evaluation of the materials# mechanical properties. Specifically, we anticipate creating surfaces that can withstand flow speeds with length-based Reynolds number exceeding 1x10^6 and friction-based Reynolds number exceeding 5000, as well as generate flow speeds ~1.5-10 m/second.--Relevance. Of primary importance to this ONR program is developing prototype surfaces (either dynamic mechanical, chemical, or biological) that alter their form based on natural variations in external stimuli acting on the marine environment. A novel feature of our work is that the stimuli trigger a force that in turn mitigates the stimuli#s effects, making our systems self-regulating, and thus possessing vital biomimetic functionality.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 24, 2025
- Source ID
- N000142512127
Entities
People
- Daniel Wangpraseurt
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego