Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed the film in thickness and expanded it in area, producing strains up to 30 to 40%. It is now shown that prestraining the film further improves the performance of these devices. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers using biaxially and uniaxially prestrained films. The strain, pressure, and response time of silicone exceeded those of natural muscle; specific energy densities greatly exceeded those of other field-actuated materials. Because the actuation mechanism is faster than in other high-strain electroactive polymers, this technology may be suitable for diverse applications.

http://science.sciencemag.org/content/sci/287/5454/836.full.pdf

High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%

Flexible pressure sensors are essential parts of an electronic skin to allow future biomedical prostheses and robots to naturally interact with humans and the environment. Mobile biomonitoring in long-term medical diagnostics is another attractive application for these sensors. Here we report the fabrication of flexible pressure-sensitive organic thin film transistors with a maximum sensitivity of 8.4 kPa(-1), a fast response time of 15,000 cycles and a low power consumption of <1 mW. The combination of a microstructured polydimethylsiloxane dielectric and the high-mobility semiconducting polyisoindigobithiophene-siloxane in a monolithic transistor design enabled us to operate the devices in the subthreshold regime, where the capacitance change upon compression of the dielectric is strongly amplified. We demonstrate that our sensors can be used for non-invasive, high fidelity, continuous radial artery pulse wave monitoring, which may lead to the use of flexible pressure sensors in mobile health monitoring and remote diagnostics in cardiovascular medicine.

/pdf/flexible-polymer-transistors-with-high-pressure-sensitivity-3nuszplute.pdf

Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring

Individual carbon nanotubes are like minute bits of string, and many trillions of these invisible strings must be assembled to make useful macroscopic articles. We demonstrated such assembly at rates above 7 meters per minute by cooperatively rotating carbon nanotubes in vertically oriented nanotube arrays (forests) and made 5-centimeter-wide, meter-long transparent sheets. These self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aerogel that can be densified into strong sheets that are as thin as 50 nanometers. The measured gravimetric strength of orthogonally oriented sheet arrays exceeds that of sheets of high-strength steel. These nanotube sheets have been used in laboratory demonstrations for the microwave bonding of plastics and for making transparent, highly elastomeric electrodes; planar sources of polarized broad-band radiation; conducting appliques; and flexible organic light-emitting diodes.

https://science.sciencemag.org/content/sci/309/5738/1215.full.pdf

Strong, Transparent, Multifunctional, Carbon Nanotube Sheets

Ionic liquids offer a unique suite of properties that make them important candidates for a number of energy related applications. Cation–anion combinations that exhibit low volatility coupled with high electrochemical and thermal stability, as well as ionic conductivity, create the possibility of designing ideal electrolytes for batteries, super-capacitors, actuators, dye sensitised solar cells and thermo-electrochemical cells. In the field of water splitting to produce hydrogen they have been used to synthesize some of the best performing water oxidation catalysts and some members of the protic ionic liquid family co-catalyse an unusual, very high energy efficiency water oxidation process. As fuel cell electrolytes, the high proton conductivity of some of the protic ionic liquid family offers the potential of fuel cells operating in the optimum temperature region above 100 °C. Beyond electrochemical applications, the low vapour pressure of these liquids, along with their ability to offer tuneable functionality, also makes them ideal as CO2 absorbents for post-combustion CO2 capture. Similarly, the tuneable phase properties of the many members of this large family of salts are also allowing the creation of phase-change thermal energy storage materials having melting points tuned to the application. This perspective article provides an overview of these developing energy related applications of ionic liquids and offers some thoughts on the emerging challenges and opportunities.

/pdf/energy-applications-of-ionic-liquids-4xj70drpc5.pdf

Energy applications of ionic liquids

Fundamentals, processes and applications of high-permittivity polymer–matrix composites

The electrostriction of elastomeric polymer dielectrics with compliant electrodes is potentially useful as a small-scale, solid-state actuator technology. Electrostrictive polymer (EP) materials are capable of efficient and fast response with high strains (> 30%), good actuation pressures (up to 1.9 MPa), and high specific energy densities (up to 0.1 J g−1). In this article, the mechanism of electrostriction is shown to be due to the electrostatic attraction of free charges on the electrodes. Although EP actuators are electrostatics based, they are shown to produce 5–20 times the effective actuation pressure of conventional air-gap electrostatics at the same electric field strength. The thin uniform dielectric films necessary for fabrication of EP actuators have been fabricated by techniques such as spin coating, casting, and dipping. A variety of materials and techniques have been used to produce the compliant electrodes, including lift-off stenciling techniques for powdered graphite, selective wetting of ionically conductive polymers, and spray coating of carbon blacks and fibrils in polymeric binders. Prototype actuators have been demonstrated in a variety of configurations such as stretched films, stacks, rolls, tubes, and unimorphs. Potential applications of the technology in areas such as microrobots, sound generators, and displays are discussed in this article.

Electrostriction of polymer dielectrics with compliant electrodes as a means of actuation

Dielectric elastomers are a new class of actuator materials that exhibit excellent performance. The principle of operation, as well as methods to fabricate and test these elastomers, is summarized here. The Figure is a sketch of an elastomer film (light gray) stretched on a frame (black) and patterned with an electrode (mid-gray). Upon applying a voltage, the active portion of the elastomer expands and the strain can easily be measured optically.

High-Strain Actuator Materials Based on Dielectric Elastomers

Many new robotic and teleoperated applications require a high degree of mobility or dexterity that is difficult to achieve with current actuator technology. Natural muscle is an actuator that has many features, including high energy density, fast speed of response, and large stroke, that are desirable for such applications. The electrostriction of polymer dielectrics with compliant electrodes can be used in electrically controllable, muscle-like actuators. These electrostrictive polymer artificial muscle (EPAM) actuators can produce strains of up to 30% and pressures of up to 1.9 MPa. The measured specific energy achieved with polyurethane and silicone polymers exceeds that of electromagnetic, electrostatic, piezoelectric, and magnetostrictive actuators. A simple model using linear elastic theory can predict EPAM actuator performance from mechanical and electrical material properties and load conditions. A spherical joint for a highly articulated (snake-like) manipulator using EPAM actuator elements has been demonstrated. A rotary motor using EPAM actuator elements has been shown to produce a specific torque of 19 mNm/g and a specific power of 0.1 W/g. An improved EPAM motor could produce greater specific power and specific torque than could electric motors.

Electrostrictive polymer artificial muscle actuators

Descriπbed herein is electroadhesion technology that permits controllable adherence between two objects Electroadhesion uses electrostatic forces of attraction produced by an electrostatic adhesion voltage, which is applied using electrodes (18) in an electroadhesive device The electrostatic adhesion voltage produces an electric field and electrostatic adherence forces When the electroadhesive device and electrodes are positioned near a surface of an object such as a vertical wall (16), the electrostatic adherence forces hold the electroadhesive device in position relative to the surface and object This can be used to increase traction or maintain the position of the electroadhesive device relative to a surface Electric control of the electrostatic adhesion voltage permits the adhesion to be controllably and readily turned on and off.

Wall crawling devices

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Roy D. Kornbluh

Author Tools

Chat about Author