Fabrication of Stretchable Copper Coated Carbon Nanotube Conductor for Non-Enzymatic Glucose Detection Electrode with Low Detection Limit and Selectivity.

The increasing demand for wearable glucose sensing has stimulated growing interest in stretchable electrodes. The development of the electrode materials having large stretchability, low detection limit, and good selectivity is the key component for constructing high performance wearable glucose sensors. In this work, we presented fabrication of stretchable conductor based on the copper coated carbon nanotube sheath-core fiber, and its application as non-enzymatic electrode for glucose detection with high stretchability, low detection limit, and selectivity.

Controllable Preparation of Ordered and Hierarchically Buckled Structures for Inflatable Tumor Ablation, Volumetric Strain Sensor, and Communication via Inflatable Antenna.

Inflatable conducting devices providing improved properties and functionalities are needed for diverse applications. However, the difficult part in making high-performance inflatable devices is the enabling of two-dimensional (2D) buckles with controlled structures on inflatable catheters. Here, we report the fabrication of highly inflatable devices with controllable structures by wrapping the super-aligned carbon nanotube sheet (SACNS) on the pre-inflated catheter.

High-Performance Biscrolled MXene/Carbon Nanotube Yarn Supercapacitors.

Yarn-shaped supercapacitors (YSCs) once integrated into fabrics provide promising energy storage solutions to the increasing demand of wearable and portable electronics. In such device format, however, it is a challenge to achieve outstanding electrochemical performance without compromising flexibility. Here, MXene-based YSCs that exhibit both flexibility and superior energy storage performance by employing a biscrolling approach to create flexible yarns from highly delaminated and pseudocapacitive MXene sheets that are trapped within helical yarn corridors are reported.

Thermoacoustic sound projector: exceeding the fundamental efficiency of carbon nanotubes.

The combination of smooth, continuous sound spectra produced by a sound source having no vibrating parts, a nanoscale thickness of a flexible active layer and the feasibility of creating large, conformal projectors provoke interest in thermoacoustic phenomena. However, at low frequencies, the sound pressure level (SPL) and the sound generation efficiency of an open carbon nanotube sheet (CNTS) is low. In addition, the nanoscale thickness of fragile heating elements, their high sensitivity to the environment and the high surface temperatures practical for thermoacoustic sound generation necessitate protective encapsulation of a freestanding CNTS in inert gases.

Flexible and Compressible Temperature Sensors Based on Hierarchically Buckled Carbon Nanotube/Rubber Bi-Sheath-Core Fibers.

Flexible and compressible temperature sensors are highly desired for artificial skin and epidermal electronics. Here we demonstrated a flexible and compressible resistive temperature sensor using hierarchically buckled carbon nanotube/rubber bi-sheath-core structure (a buckled carbon nanotube outer sheath and a buckled rubber inner sheath wrapped around a rubber fiber core). When heated, lateral contacts of the adjacent buckles increase, resulting in electrical resistance decrease and serving as highly sensitive temperature sensors.

Harvesting electrical energy from carbon nanotube yarn twist.

Mechanical energy harvesters are needed for diverse applications, including self-powered wireless sensors, structural and human health monitoring systems, and the extraction of energy from ocean waves. We report carbon nanotube yarn harvesters that electrochemically convert tensile or torsional mechanical energy into electrical energy without requiring an external bias voltage. Stretching coiled yarns generated 250 watts per kilogram of peak electrical power when cycled up to 30 hertz, as well as up to 41.

Ultrastretchable Analog/Digital Signal Transmission Line with Carbon Nanotube Sheets.

Stretchable conductors can be used in various applications depending on their own characteristics. Here, we demonstrate simple and robust elastomeric conductors that are optimized for stretchable electrical signal transmission line. They can withstand strains up to 600% without any substantial change in their resistance (≤10% as is and ≤1% with passivation), and exhibit suppressed charge fluctuations in the medium.

Electrochemically Powered, Energy-Conserving Carbon Nanotube Artificial Muscles.

While artificial muscle yarns and fibers are potentially important for many applications, the combination of large strokes, high gravimetric work capacities, short cycle times, and high efficiencies are not realized for these fibers. This paper demonstrates here electrochemically powered carbon nanotube yarn muscles that provide tensile contraction as high as 16.5%, which is 12.

Relationship between nanotopographical alignment and stem cell fate with live imaging and shape analysis.

The topography of a biomaterial regulates cellular interactions and determine stem cell fate. A complete understanding of how topographical properties affect cell behavior will allow the rational design of material surfaces that elicit specified biological functions once placed in the body. To this end, we fabricate substrates with aligned or randomly organized fibrous nanostructured topographies.

Flow-less and shape-conformable CNT sheet nanogenerator for self-powered motion sensor.

A carbon nanotube (CNT) sheet nanogenerator that does not require any liquid or gas flow for power generation is developed on the basis of Coulombic interactions, making the device attractive as a building block for self-powered sensors. The working principle of the CNT nanogenerator is probed in terms of sweeping speed, distance between charged object and nanotube sheet, surface charge, and number of layers of nanotube sheet. The nature of the CNT sheet and its formation process is such that simply winding the CNT sheet stripe n times around a substrate leads to increasing the power n times.

Conducting Fibers: Downsized Sheath-Core Conducting Fibers for Weavable Superelastic Wires, Biosensors, Supercapacitors, and Strain Sensors (Adv. Mater. 25/2016).

Using intelligent textiles for clothing represents one possibility for weavable superelastic conducting fibers that can store energy, sense body motions, and detect biochemicals. On page 4998, S. Yin, R.

Strong, Twist-Stable Carbon Nanotube Yarns and Muscles by Tension Annealing at Extreme Temperatures.

A high-speed incandescent tension annealing process (ITAP) is used to increase the modulus and strength of twist-spun carbon nanotube yarns by up to 12-fold and 2.6-fold, respectively, provide remarkable resistance to oxidation and powerful protonating acids, and freeze yarn untwist. This twist stability enables torsional artificial-muscle motors having improved performance and minimizes problematic untwist during weaving nanotube yarns.

Downsized Sheath-Core Conducting Fibers for Weavable Superelastic Wires, Biosensors, Supercapacitors, and Strain Sensors.

Hair-like-diameter superelastic conducting fibers, comprising a buckled carbon nanotube sheath on a rubber core, are fabricated, characterized, and deployed as weavable wires, biosensors, supercapacitors, and strain sensors. These downsized sheath-core fibers provide the demonstrated basis for glucose sensors, supercapacitors, and electrical interconnects whose performance is undegraded by giant strain, as well as ultrafast strain sensors that exploit strain-dependent capacitance changes.

High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes.

Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application.

Nanotube aerogel sheet flutter for actuation, power generation, and infrasound detection.

Electromagnetic induction (EMI) is a mechanism of classical physics that can be utilized to convert mechanical energy to electrical energy or electrical to mechanical energy. This mechanism has not been exploited fully because of lack of a material with a sufficiently low force constant. We here show that carbon nanotube (CNT) aerogel sheets can exploit EMI to provide mechanical actuation at very low applied voltages, to harvest mechanical energy from small air pressure fluctuations, and to detect infrasound at inaudible frequencies below 20 Hz.

Primary liver cells cultured on carbon nanotube substrates for liver tissue engineering and drug discovery applications.

Here, we explore the use of two- and three-dimensional scaffolds of multiwalled-carbon nanotubes (MWNTs) for hepatocyte cell culture. Our objective is to study the use of these scaffolds in liver tissue engineering and drug discovery. In our experiments, primary rat hepatocytes, the parenchymal (main functional) cell type in the liver, were cultured on aligned nanogrooved MWNT sheets, MWNT yarns, or standard 2-dimensional culture conditions as a control.

Superior rechargeability and efficiency of lithium-oxygen batteries: hierarchical air electrode architecture combined with a soluble catalyst.

The lithium-oxygen battery has the potential to deliver extremely high energy densities; however, the practical use of Li-O2 batteries has been restricted because of their poor cyclability and low energy efficiency. In this work, we report a novel Li-O2 battery with high reversibility and good energy efficiency using a soluble catalyst combined with a hierarchical nanoporous air electrode. Through the porous three-dimensional network of the air electrode, not only lithium ions and oxygen but also soluble catalysts can be rapidly transported, enabling ultra-efficient electrode reactions and significantly enhanced catalytic activity.

Regulation of morphogenesis and neural differentiation of human mesenchymal stem cells using carbon nanotube sheets.

In order to successfully utilize stem cells for therapeutic applications in regenerative medicine, efficient differentiation into a specific cell lineage and guidance of axons in a desired direction is crucial. Here, we used aligned multi-walled carbon nanotube (MWCNT) sheets to differentiate human mesenchymal stem cells (hMSCs) into neural cells. Human MSCs present a preferential adhesion to aligned CNT sheets with longitudinal stretch parallel to the CNT orientation direction.

Hybrid nanomembranes for high power and high energy density supercapacitors and their yarn application.

We report mechanically robust, electrically conductive, free-standing, and transparent hybrid nanomembranes made of densified carbon nanotube sheets that were coated with poly(3,4-ethylenedioxythiophene) using vapor phase polymerization and their performance as supercapacitors. The hybrid nanomembranes with thickness of ~66 nm and low areal density of ~15 μg/cm(2)exhibited high mechanical strength and modulus of 135 MPa and 12.6 GPa, respectively.

A reel-wound carbon nanotube polarizer for terahertz frequencies.

Utilizing highly oriented multiwalled carbon nanotube aerogel sheets, we fabricated micrometer-thick freestanding carbon nanotube (CNT) polarizers. Simple winding of nanotube sheets on a U-shaped polyethylene reel enabled rapid and reliable polarizer fabrication, bypassing lithography or chemical etching processes. With the remarkable extinction ratio reaching ∼37 dB in the broad spectral range from 0.

Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells.

Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes.