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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Androids: application of EAP as artificial muscles to entertainment industry

The classic movie Metropolis (1926), which is nowadays considered a cinema milestone, has shown the possibility to build robots called androids that are science and fiction run together to realize a dream: the human-like robot. In that movie, Dr. Rotwang transforms a simple and cold calculating robot into the body of a beautiful woman. Robots have often been depicted as metal creatures with cold steel bodies, but there is no reason why metals should be the only kind of material for construction of robots. The authors examined the issues related to applying electroactive polymers materials (EAP) to the entertainment industry. EAP are offering attractive characteristics with the potential to produce more realistic models of living creatures at significantly lower cost. This paper seeks to elucidate how EAP might infiltrate and ultimately revolutionize entertainment, showing some applicative examples.

Animatronics↗
NASA NTRS2004

Characterization of bending EAP beams

Electroactive polymers are attractive actuation materials because of their large deformation, flexibility, and lightweight. A CCD camera system was constructed to record the curved shapes of bending during the activation of EAP films and image-processing software was developed to digitize the bending curves. A computer program was developed to solve the invese problem of cantilever EAP beams with tip position limiter. using the developed program and acquired curves without tip position limiter as well as the corresponding tip force, the EAP material properties of voltage-strain sensitivity and Young's modulus were determined.

large deformation↗
NASA NTRS2006

Biomimetics as a Model for Inspiring Human Innovation

Electroactive polymers (EAP) are human made actuators that are the closest to mimic biological muscles. Technology was advanced to the level that biologically inspired robots are taking increasing roles in the world around us and making science fiction ideas a closer engineering reality. Artificial technologies (AI, AM, and others) are increasingly becoming practical tools for making biologically inspired devices and instruments with enormous potential for space applications. Polymer materials are used to produce figures that resemble human and animals. These materials are widely employed by the movie industry for making acting figures and by the orthopedic industry to construct cyborg components. There are still many challenges ahead that are critical to making such possibilities practical. The annual armwrestling contest is providing an exciting measure of how well advances in EAP are implemented to address the field challenges. There is a need to document natures inventions in an engineering form to possibly inspire new capabilities.

Electroactive Polymers (EAP)↗
NASA NTRS2009

Humanlike Robots - The Upcoming Revolution in Robotics

Humans have always sought to imitate the human appearance, functions and intelligence. Human-like robots, which for many years have been a science fiction, are increasingly becoming an engineering reality resulting from the many advances in biologically inspired technologies. These biomimetic technologies include artificial intelligence, artificial vision and hearing as well as artificial muscles, also known as electroactive polymers (EAP). Robots, such as the vacuum cleaner Rumba and the robotic lawnmower, that don't have human shape, are already finding growing use in homes worldwide. As opposed to other human-made machines and devices, this technology raises also various questions and concerns and they need to be addressed as the technology advances. These include the need to prevent accidents, deliberate harm, or their use in crime. In this paper the state-of-the-art of the ultimate goal of biomimetics, the development of humanlike robots, the potentials and the challenges are reviewed.

EAP↗
NASA NTRS2010

Refreshable Braille Displays Using EAP Actuators

Refreshable Braille can help visually impaired persons benefit from the growing advances in computer technology. The development of such displays in a full screen form is a great challenge due to the need to pack many actuators in small area without interferences. In recent years, various displays using actuators such as piezoelectric stacks have become available in commercial form but most of them are limited to one line Braille code. Researchers in the field of electroactive polymers (EAP) investigated methods of using these materials to form full screen displays. This manuscript reviews the state of the art of producing refreshable Braille displays using EAP-based actuators..

Electroactive Polymers↗
NASA NTRS2002

Characterization of the electromechanical properties of ionomeric polymer-metal composite (IPMC)

IPMC is an electroactive polymer (EAP) that has been the subject of research and development since 1992. Its required low activation voltage and the large bending strain led to its consideration for various potential applications. However, before the benefits of IPMC can be effectively exploited for practical use, the electromechanical behavior of this group of EAP materials must be properly understood and quantified.

EAP↗
NASA NTRS1999

Electro-Statically Stricted Polymers (ESSP)

Miniature, lightweight, miser actuators that operate similar to biological muscles can be used to develop robotic devices with unmatched capabilities and impact many technology areas. Electroactive polymers (EAP) offer the potential to producing such actuators and their main attractive feature is their ability to induce relatively large bending or longitudinal strain.

EAP↗
DOE OSTI2016

Engineered Elastomer Substrates for Guided Assembly of Complex 3D Mesostructures by Spatially Nonuniform Compressive Buckling

Approaches capable of creating 3D mesostructures in advanced materials (device-grade semiconductors, electroactive polymers, etc.) are of increasing interest in modern materials research. A versatile set of approaches exploits transformation of planar precursors into 3D architectures through the action of compressive forces associated with release of prestrain in a supporting elastomer substrate. Although a diverse set of 3D structures can be realized in nearly any class of material in this way, all previously reported demonstrations lack the ability to vary the degree of compression imparted to different regions of the 2D precursor, thus constraining the diversity of 3D geometries. This paper presents a set of ideas in materials and mechanics in which elastomeric substrates with engineered distributions of thickness yield desired strain distributions for targeted control over resultant 3D mesostructures geometries. This approach is compatible with a broad range of advanced functional materials from device-grade semiconductors to commercially available thin films, over length scales from tens of micrometers to several millimeters. A large range of 3D structures can be produced in this way, some of which have direct relevance to applications in tunable optics and stretchable electronics.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Flexible MXene/Graphene Films for Ultrafast Supercapacitors with Outstanding Volumetric Capacitance

A strategy to prepare flexible and conductive MXene/graphene (reduced graphene oxide, rGO) supercapacitor electrodes by using electrostatic self-assembly between positively charged rGO modified with poly(diallyldimethylammonium chloride) and negatively charged titanium carbide MXene nanosheets is presented. After electrostatic assembly, rGO nanosheets are inserted in-between MXene layers. As a result, the self-restacking of MXene nanosheets is effectively prevented, leading to a considerably increased interlayer spacing. Accelerated diffusion of electrolyte ions enables more electroactive sites to become accessible. The freestanding MXene/rGO-5 wt% electrode displays a volumetric capacitance of 1040 F cm –3 at a scan rate of 2 mV s –1 , an impressive rate capability with 61% capacitance retention at 1 V s –1 and long cycle life. Moreover, the fabricated binder-free symmetric supercapacitor shows an ultrahigh volumetric energy density of 32.6 Wh L –1 , which is among the highest values reported for carbon and MXene based materials in aqueous electrolytes. Furthermore, this work provides fundamental insight into the effect of interlayer spacing on the electrochemical performance of 2D hybrid materials and sheds light on the design of next-generation flexible, portable and highly integrated supercapacitors with high volumetric and rate performances.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Knittable and Washable Multifunctional MXene-Coated Cellulose Yarns

Textile-based electronics enable the next generation of wearable devices, which have the potential to transform the architecture of consumer electronics. Highly conductive yarns that can be manufactured using industrial-scale processing and be washed like everyday yarns are needed to fulfill the promise and rapid growth of the smart textile industry. By coating cellulose yarns with Ti 3 C 2 T x MXene, highly conductive and electroactive yarns are produced, which can be knitted into textiles using an industrial knitting machine. It is shown that yarns with MXene loading of ≈77 wt% (≈2.2 mg cm -1 ) have conductivity of up to 440 S cm -1 . After washing for 45 cycles at temperatures ranging from 30 to 80 °C, MXene-coated cotton yarns exhibit a minimal increase in resistance while maintaining constant MXene loading. The MXene-coated cotton yarn electrode offers a specific capacitance of 759.5 mF cm -1 at 2 mV s -1 . Additionally, a fully knitted textile-based capacitive pressure sensor is also prepared, which offers high sensitivity (gauge factor of ≈6.02), wide sensing range of up to ≈20% compression, and excellent cycling stability (2000 cycles at ≈14% compression strain). This work provides new and practical insights toward the development of platform technology that can integrate MXene in cellulose-based yarns for textile-based devices.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Stable Metal Anode enabled by Porous Lithium Foam with Superior Ion Accessibility

Abstract Lithium (Li) metal anodes have attracted much interest recently for high‐energy battery applications. However, low coulombic efficiency, infinite volume change, and severe dendrite formation limit their reliable implementation over a wide range. Here, an outstanding stability for a Li metal anode is revealed by designing a highly porous and hollow Li foam. This unique structure is capable of tackling many Li metal problems simultaneously: first, it assures uniform electrolyte distribution over the inner and outer electrode's surface; second, it reduces the local current density by providing a larger electroactive surface area; third, it can accommodate volume expansion and dissipate heat efficiently. Moreover, the structure shows superior stability compared to fully Li covered foam with low porosity, and bulky Li foil electrode counterparts. This Li foam exhibits small overpotential (≈25 mV at 4 mA cm −2 ) and high cycling stability for 160 cycles at 4 mA cm −2 . Furthermore, when assembled, the porous Li metal as the anode with LiFePO 4 as the cathode for a full cell, the battery has a high‐rate performance of 138 mAh g −1 at 0.2 C. The beneficial structure of the Li hollow foam is further studied through density functional theory simulations, which confirms that the porous structure has better charge mobility and more uniform Li deposition.

Hafez, Ahmed M.↗
DOE OSTI2022

Solution-Deposited and Patternable Conductive Polymer Thin-Film Electrodes for Microbial Bioelectronics

Microbial bioelectronic devices integrate naturally occurring or synthetically engineered electroactive microbes with microelectronics. These devices have a broad range of potential applications, but engineering the biotic–abiotic interface for biocompatibility, adhesion, electron transfer, and maximum surface area remains a challenge. Prior approaches to interface modification lack simple processability, the ability to pattern the materials, and/or a significant enhancement in currents. We report a novel conductive polymer coating that significantly enhances current densities relative to unmodified electrodes in microbial bioelectronics is reported. The coating is based on a blend of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) crosslinked with poly(2-hydroxyethylacrylate) (PHEA) along with a thin polydopamine (PDA) layer for adhesion to an underlying indium tin oxide (ITO) electrode. When used as an interface layer with the current-producing bacterium Shewanella oneidensis MR-1, this material produces a 178-fold increase in the current density compared to unmodified electrodes, a current gain that is higher than previously reported thin-film 2D coatings and 3D conductive polymer coatings. The chemistry, morphology, and electronic properties of the coatings are characterized and the implementation of these coated electrodes for use in microbial fuel cells, multiplexed bioelectronic devices, and organic electrochemical transistor based microbial sensors are demonstrated. It is envisioned that this simple coating will advance the development of microbial bioelectronic devices.

patterned bioelectronics↗