Institution: University of Michigan, Ann Arbor MI.
Proposal No: 0937323
The research project is a collaborative interdisciplinary study to create a transformative multifunctional adaptive engineering structure concept through investigating the characteristics of plants. The investigators propose to explore new bio-actuation/bio-sensing ideas building upon innovations inspired by the mechanical, chemical, and electrical properties of plant cells. It has been observed that plant nastic actuations (e.g., rapid plant motions of Venus Flytrap or Mimosa) occur due to directional changes in plant cell shape facilitated by internal hydrostatic pressure, achieving actuations with large force and stroke. It is also known that plants can adapt to the direction/magnitude of external loads and damage, and reconfigure or heal themselves via cell growth. The ability to concurrently achieve distributed large stroke/force actuation, significant property change, self-sensing, reconfiguration, and self-healing has long been the dream of the adaptive structures researchers. The bio-sensing/ actuation features of plants can provide engineers with valuable knowledge and opportunities for interdisciplinary intellectual advancements that could lead to a new paradigm of adaptive structures and impact the joint field of bioscience and engineering significantly.
The intellectual merit of this project is that the multidisciplinary research team will push forward advancements in various disciplines at their interfaces (plant and cell biology, materials and manufacturing, chemical transport, mechatronics, and structural dynamics and controls) and utilize the synergy to create a significant leap in fundamental knowledge for future adaptive materials and structures. By physiological characterization of how plant cell wall organization influences cell shape changes during rapid plant motions, the team will investigate the wall fibrillar networks and the orientations of plant cells that can achieve the most effective nastic actions. Building upon and advancing from the investigators? study of the promising fluidic flexible matrix composite (F2MC) concept, F2MC cells will be created that emulate functions of plant cells based on our improved understanding of the cell wall response to pressure, loading, and damage. Advanced nanofiber networking capability will be explored for the F2MC materials. Inspired by the plant cell membrane transport phenomenon, a microstructure will be developed that generates pressure to actuate the F2MC cells, senses and regulates pressure, detects damage, and heals. Through structural analysis and control synthesis, F2MC cells will be assembled to form a hypercellular topology resembling a circulatory network for global actuation and structural control, energy harvesting, thermal management, and self healing.
The outcome of this project is expected to impact the society broadly and significantly. The findings could become the building blocks of future mechanical, civil, transportation, and aerospace systems with enhanced functionality and performance. The next generation of air, marine, and land vehicles, intelligent machines, and smart infrastructure will benefit greatly from the knowledge discovery. The investigators will integrate the emerging frontier research with educational programs to achieve broad impact on learning at various levels, contributing to the workforce training on multidisciplinary systems crossing biology and engineering.
Section 1 Project Outcome and Findings Normal 0 false false false EN-US X-NONE X-NONE This project explored new adaptive structure ideas inspired by the mechanical, chemical, and electrical properties of plant cells. The intellectual outcome and findings can be summarized as follows. Plant Biology Plants, unlike animals, surround each cell with a specialized structure that is designed to resist high internal pressures of up to five to ten atmospheres (roughly the same pressure found in a fully inflated bicycle tire). These cell walls provide the strength and rigidity that dictates cell shape, and provides the structural integrity that allows the plant to grow vertically. Plant cell walls are made up of specialized chains of sugars, called polysaccharides, the most important of which is cellulose. In this project, we investigated the patterns in which cellulose polysaccharides were made and integrated into the plant cell wall in order to understand whether these patterns affected the ways in which the plant cell could change shape. The funding supported the development of new automated computational methods that allow us to rapidly measure the overall organization of cellulose polysaccharide networks in plant cells. In addition, this funding was important to our discovery of a completely new class of enzymes that control the synthesis of cellulose in a specialized class of plant cells called root hair cells. Actuation and Control We first developed a plant-inspired device that can generate pressure from a difference in the concentration of molecules dissolved in two water compartments that are separated by a membrane. This membrane is semi-permeable and hence permeable only to water but not the dissolved molecules. Pressure is generated by osmosis, i.e. the tendency of water to move into the compartment with the highest concentration of dissolved molecules. The second development involved a biomimetic design of the semi-permeable membranes that are used in living cells. These membranes have high surface area to volume ratios, are only a few nanometers thick and harbor special protein pores for water such that they support extremely fast flux of water. Insights on the dynamics of osmosis-based pressure generation provide fundamental understanding of the pressure generation in plants, and are useful to drive fluidic devices in resource poor environments. Manufacturing We focused on the manufacturing of a plant cell inspired structural element called fluidic flexible matrix composite (F2MC). Innovative methods of manufacturing small-diameter F2MC tubes were developed in the current investigation. The materials consist of high stiffness fibers embedded in elastomeric matrix materials. Such tubes mimic the cell wall structure of plants and enable adaptive properties such as variable shape and stiffness and energy absorption based on the manipulation of fluid pressure inside the tubes. The fiber reinforcements were in the form of short carbon nanofibers, continuous carbon fibers, and continuous stainless steel wires. The main goal of reducing the diameter of the tubes by a factor of 10 versus the prior state-of-the-art was achieved. Design tools and test methods were developed for adaptive structures employing F2MC tubes. System Level Integration and Synthesis Building upon the above areas, this part focused on system level investigations. We developed a new class of vibration damping treatments called fluidlastic technology, which is energy efficient and inexpensive. Several specialized test fixtures were built to enable F2MC structure integration. Fluidlastic technology had the potential to reduce sound and vibration in challenging applications such as rotorcraft so that it could reduce health issues and improve the quality of life for the users. It is also recognized that when different F2MC tubes are strategically integrated into a larger-scale structure, the system can achieve very high performance. Mathematical models are derived to uncover the linkage between the overall system performances and the design of each individual F2MC tube. Based on such knowledge, rigorous synthesis tools are developed to select the appropriate design parameters for each F2MC so that together they could achieve the desired actuation, variable stiffness, and vibration management performance concurrently. Overall, the outcome of this project will impact the technical community and the society broadly and significantly. The findings could become the building blocks of future mechanical, civil, transportation, and aerospace systems and will enhance their functionality tremendously. The next generation of air, marine, and land vehicles, intelligent machines, and infrastructure will benefit greatly from the knowledge derived from the transformative adaptive structure idea. The investigators have performed curricula development in bio-inspired adaptive structures, and integrated research with educational programs to achieve broad impact on student learning at various levels and community outreach with diversity. Normal 0 false false false EN-US X-NONE X-NONE Section 2 Products (other products in addition to publications) Normal 0 false false false EN-US X-NONE X-NONE 1. Open-source numerical simulation tool for modeling osmosis-based pressure generation is available at: http://sourceforge.net/projects/osmoticpressurizationdynamics/files/. 2. YouTube videos of mimosa-like actuation based on F2MC, for education purpose: www.youtube.com/watch?v=pbFiFvfHxRE www.youtube.com/watch?v=UaCcDH-Zopg
