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Electroactive Polymer (EAP) Actuators for Future Humanlike Robots
Human-like robots are increasingly becoming an engineering reality thanks to recent technology advances. These robots, which are inspired greatly by science fiction, were originated from the desire to reproduce the human appearance, functions and intelligence and they may become our household appliance or even companion. The development of such robots is greatly supported by emerging biologically inspired technologies. Potentially, electroactive polymer (EAP) materials are offering actuation capabilities that allow emulating the action of our natural muscles for making such machines perform lifelike. There are many technical issues related to making such robots including the need for EAP materials that can operate as effective actuators. Beside the technology challenges these robots also raise concerns that need to be addressed prior to forming super capable robots. These include the need to prevent accidents, deliberate harm, or their use in crimes. In this paper, the potential EAP actuators and the challenges that these robots may pose will be reviewed.
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..
Directions for Development of the Field of Electroactive Polymer (EAP)
In last few years, the rate of development and advances in the field of EAP has accelerated significantly and it is increasingly getting closer to the point of finding them used in commercial products. Substantial development has been reported in the understanding of their drive mechanisms and the parameters that control their electro-activation behavior. Further, efforts are being made to develop mass production techniques with greatly improved actuation capability and operation durability. The recent efforts to develop energy harvesting techniques, haptic interfacing (including refreshable braille displays), and toys are further increasing the likelihood of finding niches for these materials. In this paper, the author sought to examine the potential directions for the future development of the field of EAP in relation to the state-of-the-art.
Synthetic Biological Membrane
The ultimate goal of the Synthetic Biological Membrane project is to develop a new type of membrane (using FOST - Forward Osmosis Secondary Treatment) that will enable the waste water treatment system required on exploration missions to operate for extended periods while requiring no maintenance, and using only available resources. Because current water treatment systems have a lifetime of less than 1 year, extending membrane life will benefit exploration missions by reducing upmass and crew time requirements associated with maintenance and resupply/replacement of membranes. The project will use synthetic biology to engineer organisms that protect and replenish the membrane, and this new technology can be easily adapted for use in terrestrial waste water treatment plants.
Auto-Gopher-2 - Wireline Deep Sampler Driven by Percussive Piezoelectric Actuator and Rotary EM Motors
Two of the key purposes of future NASA’s solar system exploration of planetary bodies are the search for potentially preserved bio-signatures and for habitable regions. To address these objectives, a biologically inspired wireline deep rotary-percussive drill, called Auto-Gopher, has been developed. This drill employs a piezoelectric-actuated percussive mechanism for generating impulsive stresses and breaking formations, and an electric motor to rotate the bit to break material and remove the cuttings. Initially, the drill was designed as percussive mechanism for sampling ice and was demonstrated in 2005 at Lake Vida, Antarctica, reaching about 2 meters depth. The lessons learned suggested there is a need to augment the percussive action with bit rotation in order to maximize the penetration rate. The first generation implementation of the rotary augmentation was focused on the demonstration of this capability. In 2012, during the 3-day field test, the drill reached a 3-meter deep in gypsum. A separate mechanism was used to break and remove the cores. The average drilling power consumption was in the range of 100-150 Watts, while the rate of penetration was approximately 2.4 meters per hour. Currently under development is the second-generation drill, called Auto-Gopher-2. The drill will be fully autonomous. In this paper, the capabilities that are being integrated into the Auto-Gopher-2 are described and discussed.
Bio-inspired Surface Structures to Mitigate Interfacial Particle Adhesion and Erosion - A Review
Lunar dust known as regolith is a huge challenge for lunar exploration missions. Formed over millennia by a complex process involving impacts of meteoroids and micrometeoroids on the lunar surface, lunar dust is porous, highly abrasive with sharp jagged edges, chemically reactive, electrostatically charged and sometimes magnetic. The chemical composition and thickness of the dust layer also varies in different regions of the lunar surface. From samples obtained by previous lunar missions, the average particle size is below 100 microns. This dust has the tendency to strongly adhere to any exposed surfaces, and often degrades the material functionality to eventually cause failure. Any material on the lunar surface is also subject to harsh temperature cycles ranging from -178 ̊C to + 123 ̊C and extreme ultraviolet radiation. While on the lunar surface, different classes of materials would be required for different applications. Advanced materials have been and will be used throughout the lunar lander, habitat, and mission equipment. Examples include: polymeric materials for astronaut protective clothing; metals and ceramics for the lunar lander legs and habitats, and excavating equipment; and semiconductors for solar panels and on-board electronics. In all these applications, the surfaces of the materials are expected or understood to be exposed to the extreme lunar environment condition that includes the regolith dust. During the Apollo missions, the dust clung to and abraded the astronaut’s suits, degraded seals, optics, clogged sensors and reduced performance of thermal radiators. The lunar dust adheres to the surface by various mechanisms, which include electrostatic and Coulombic interactions, Van-der-Waals forces, magnetic forces, mechanical interlocking, chemical bonding and donor-acceptor interactions. There are three primary strategies for developing technologies to minimize the lunar dust adhesion: active, passive and a combination of active and passive. In the active approach, an external energy is needed to prevent or remove particles from collecting on the surface. Mechanically powered brushes and electrodynamic dust screens are two examples. In the passive approach, no external power is needed, and the material surface properties are able to mitigate dust adhesion. A well-known example of this strategy is the low work function coatings for non-stick surfaces. In most cases a combination of active and passive methods might be needed to optimally manage the lunar regolith. The passive method is significantly more attractive as it does not require any external power or an additional control subsystem. These approaches optimize the mission payload and reduce risk. Surface modification to minimize the dust adhesion is thus very important to lunar missions. Here, naturally evolved surface structures might provide guidance for solutions. There are several factors that have to be considered for minimizing particle adhesion to a surface. These include the substrate material properties, surface topography, chemistry, and the characteristics of the adhering particles. When engineering a surface, the substrate material chosen would be dependent on the needs of the application. Tailoring the surface microstructure or chemistry opens up more possibilities for its optimal utilization
Making science fiction an engineering reality using biologically-inspired technologies
This paper reviews the state of the art and challenges to some of the biologically inspired technologies and the potential impact on the field of NDE.
Electro-active polymers: current capabilities and challenges
This paper will be a review of the status of the EAP field and the challenges to practical application of EAP materials as actuators.
Passive Lunar Dust Mitigation Materials Research
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