Collaborative Research: NRI: Smart Skins for Robotic Prosthetic Hand Lead PI: Jie Yin, Co-PI: Helen Huang (North Carolina State University) PI: Chenglin Wu (Missouri University of Science and Technology), PI: Bo Li (Villanova University) Overview: Humans have developed dexterous control of hand grasps without detailed motion planning at the actuator/effector levels. Prosthetic hands mimic the structure and appearance of human hands for object grasping. However, most current prosthetic hands miss the underpinning actuation and sensing in the biological hands, which makes it challenging to handle the slip prevention during grasping. The active and quick response to the self-sensing and slip prevention remains largely unexplored for the control of human-robotics interface. To address the challenge, through combined sensing, additively manufacturing, control, and human-robotic interactions, we are proposing a structured shape-morphing robotic skin that can actively change its multiscale surface morphologies to finely tune and enhance the friction for anti-slip. The multidisciplinary team is composed of experts in the areas of mechanics and design, small-scale additive manufacturing, sensing and materials synthesis, and human-machine intelligence. The objective of the is proposal is to fundamentally understanding the developed active shape-morphing robotic skins for slip prevention in prosthetic hands through a closed-loop design, modeling, sensing, actuation, human-in-the-loop control, and testing validation. Intellectual Merits: The proposed works will be conducted through three thrusts. Thrust 1 is to understand the fundamental relation between the smart shape-morphing robotic skin and the enhanced friction for robust grasping through combined design, mechanics modeling, fabrication, and experimental testing. Thrust 2 is to explore robotic skin sensing (spatial, pressure, and tangential forces) for slippery detection and informing. Building upon the integration of smart shape-morphing robotic skin and sensing, Trust 3 is to test the integrated interactive human-robotic system for anti-slip through object grasping protocols and controls. Broader Impacts: More than 3 million people suffer from hand amputations or loss due to health disorders caused by infections, congenital absence, diabetes, cancer or others. Over 75% of the amputations are partial. Hand loss has an important impact on the person������������������s functional aspect. If successful, the smart active skin with sensing and actuated integrated active shape-morphing for friction management will significantly advance the current state-of-the-art prosthetic hand to achieve the similar functionality of human sensorimotor system. Through both collaborative and individual efforts of the interdisciplinary team with distributed geographical location across the country (Raleigh, Philadelphia, and Rolla), the proposed research will offer a unique opportunity to integrate insights from robotics, mechanics, design, additive manufacturing to generate a theoretically intriguing and visually appealing broad participation plan. Through existing programs, such as senior design projects, Society of Women Engineering, honor program, we will encourage underrepresented groups of undergraduate students in research activities, including female and African American students. With the help of established similar summer programs and other educational programs in each institution, such as Women's Engineering Exploration summer program, we aim to improve the STEM education of K-12 students.

This Faculty Early Career Development Program (CAREER) award will support fundamental research on the mechanical behavior of kirigami-based reconfigurable two dimensional (2D) and three dimensional (3D) structures. Very recently, kirigami, the ancient paper cutting art, has inspired emerging scientific research and engineering innovations, ranging from mechanical metamaterials, stretchable devices, and solar tracking, to self-assembled 3D meso-structures. However, it largely lacks the fundamental understanding of cut-structures determined macroscopic mechanical response of kirigami structures. This research program will establish a theoretical framework for connecting the macroscopic mechanical behavior and cuts-based microstructures in a new class of kirigami-based structures, which are reconfigurable in both 2D and 3D. The knowledge developed through this project will advance multiple technologies, including scaffolds for conformable and stretchable electronics, electronic skin, adaptive energy efficient building envelope, programmable soft machines, soft robots, and reconfigurable acoustic wave guides. The education and outreach objectives will align with the research goal in generating better understanding of mechanics and structure-determined properties and functionalities in kirigami structures. Programs at Temple and museums in Philadelphia will be used to broaden the participation of K-12 in STEM, including Women's Engineering Exploration summer program and STEM education department at Temple, as well as Science museum displays (Franklin Institute) and Art show (Philadelphia Museum of Art) in Philadelphia. Kirigami-based 2D/3D structures will be constructed by applying designed cuts and/or folds to both planar sheets and bulk materials for actuation under forces or external stimuli. Systematic theoretical framework will be developed to predict the kinematics and constitutive modeling of 2D and 3D kirigami structures, with validation by numerical simulation, fabrication, and experimental testing. For 2D structures, a unified design of patterned cuts will account for both symmetric and non-symmetric deformation. The quantitative relationship between the overall mechanical properties and the geometry of localized cut structures will be determined through developed homogenization continuum model. 3D reconfigurable kirigami structures will be constructed from either (self-) folding of kirigami sheets or assembly of 3D cut polyhedron units as fundamental building blocks for architected structures. For 3D architected kirigami structures, their reconfigurability and mechanical properties will be determined by the deformation modes in localized 3D cut units. A theoretical framework will be developed to predict the overall deformation modes through mode analysis under both small and finite deformation.

Soft robots have been recently emerged as co-robots for their safe and adaptive interaction with human and environment. However, they have yet to become ubiquitous since existing ones generally have slow speed, small forces, and limited customizability. The research goal is to establish a novel theoretical and experimental framework to enhance the customizability of ubiquitous soft co-robots that will be fast, strong, and multitask, by leveraging elastic instabilities of soft modules. We propose to actively tune the energy landscape of a single or multistable multiple modules on-the-fly to generate fast, strong, and adaptive motions to different environment. The framework will be developed by synergistically integrating mechanics, design, dynamics, and real-time control; further, it will be manifested by robot prototypes at multiple scales that can jump, walk, gallop, climb, and swim.

This award supports fundamental research exploring the underlying deformation and failure mechanism governing the formation and evolution of extremely buckling driven periodic delaminated patterns with the applied mechanical strain. Buckling instability is ubiquitous in daily lives from human skin wrinkling to blisters on painted walls. It has been pursued as a versatile means to design stretchable devices, as well as dynamically tuning a variety of surface topography related properties in wetting, adhesion, and optics. The knowledge developed through this project could enable and advance multiple surface properties governed technologies, including extremely stretchable electronics, multifunctional smart windows, tunable optics, tunable structural color change for camouflage, water harvesting, self-cleaning, slippery surface, and green surfaces for anti-biofouling. This work will also provide rich research opportunities for underrepresented groups through the honor program at Temple University and the Women Engineering Exploration program broadening participation for K-12 students. Through combining a tightly coupled experimental, computational, and theoretical program, this research will explore the mechanics of spontaneously extremely buckling driven periodic delamination of thin film on soft substrates. Experimentally, extremely large pre-stretched strain will be applied to an elastomer substrate, followed by the deposition of metal or semiconductor thin films on it. The pre-strain will be released to generate large-area, periodic extremely delaminated patterns in the form of continuous thin film and discrete ribbons on both microscale and millimeter-scale. The potential cracking failure in the delaminated buckled film and ribbons during the extreme buckling will be examined through experiments and cracking models. To reveal the deformation mechanism, energy-based theoretical modeling, together with cohesive zone modeling based finite element simulation, will be developed to understand and predict the tunable geometry of periodic delaminated buckled profiles with strains. Both the theoretical modeling and numerical simulations will be compared with experiments for validation and modifications.

Cooling currently consumes about 9 percent of commercial building energy in US, and contributes significantly to urban heat island effects. As population continues to grow and shift to the city, precipitation and temperature patterns have changed so much that they add considerable stress to keep buildings and cities cool. Established architectural treatments are not adaptive to the changing environmental conditions unless a mechanical control is added. This EArly-concept Grant for Exploratory Research (EAGER) project will bring together a highly collaborative and synergistic team of architects, mechanical engineers, and materials scientists to exploit a high risk-high payoff approach, kirigami (cutting and folding), where reconfigurability and cooling processes are materialized in building envelopes that sense and actuate in response to environmental change (e.g. heat, humidity, and wind). The building envelopes will harvest dew water in the early morning and later release it via evaporation, thus, dramatically reducing the cooling load of building elements. The research project will offer a rich and diverse set of problems to excite students at all levels and general public about STEAM, and raise their awareness to address building energy needs. This EAGER project aims to create an innovative building envelope for water condensation and evaporative cooling by considering the ambient temperature, humidity, and wind loads (both indoor and outdoor), as well as the surface property and shape of the novel building materials, achieving the water collection efficiency greater than 35 g/m2h on aluminum coated polyester sheets, and temperature reduction of at least 2-3 oC on daily condensation-evaporation cycles in summer. Specifically, the researchers will 1) perform mesoscale simulation, testing, and energy evaluation on various kirigami structures to identify suitable building envelope designs; 2) Develop simple hygro-thermal models to calculate evapotranspiration in daily condensation-evaporation cycles; 3) Integrate surface coatings to the kirigami structures and test water collection efficiency and temperature change in the daily cycle and comparing with theoretical values. 4) Guided by computation modeling and finite element simulation, optimize the cut patterns to improve applicability of the building envelopes in an outdoor setting. The designed envelopes are potentially transformative: they are passively responsive yet dynamically tunable, hence requiring low maintenance; multifunctional in ways that are not possible in existing building treatments; and generic, scalable, and modularizable.