High-strength composite yarns derived from oxygen plasma modified super-aligned carbon nanotube arrays

Spinning carbon nanotube （CNT） yarns from super-aligned carbon nanotube （SACNT） arrays is a promising approach to fabricate high-strength fibers. However the reported tensile strengths of the as-prepared fibers are far below that of an individual CNT. It is therefore still a challenge to improve their mechanical strengths. Here we report that the tensile strengths and Young＇s moduli can be further improved to 2.2 GPa and 200 GPa respectively, if we first treat the SACNT array with oxygen plasma by using a reactive ion etching （RIE） facility, then dry spin yarns from it and make composite fibers with polyvinyl alcohol. According to the experimental results obtained using scanning electron microscopy （SEM）, Raman spectroscopy and X-ray photoelectron spectroscopy （XPS）, the improvement is attributed to the oxygen RIE process, as it can create functional groups on the outer walls of CNTs and thus improve the interaction between the CNTs and the polymer molecules.

Dual-Ion Co-Regulation System Enabling High-Performance Electrochemical Artificial Yarn Muscles with Energy-Free Catch States

Artificial yarn muscles show great potential in applications requiring low-energy consumption while maintaining high performance. However, conventional designs have been limited by weak ion-yarn muscle interactions and inefficient “rocking-chair” ion migration. To address these limitations, we present an electrochemical artificial yarn muscle design driven by a dual-ion co-regulation system. By utilizing two reaction channels, this system shortens ion migration pathways, leading to faster and more efficient actuation. During the charging/discharging process, PF_6~- ions react with carbon nanotube yarn, while Li~+ ions react with an Al foil. The intercalation reaction between PF_6~- and collapsed carbon nanotubes allows the yarn muscle to achieve an energy-free high-tension catch state. The dual-ion coordinated yarn muscles exhibit superior contractile stroke, maximum contractile rate, and maximum power densities, exceeding those of “rocking-chair” type ion migration yarn muscles. The dual-ion co-regulation system enhances the ion migration rate during actuation, resulting in improved performance. Moreover, the yarn muscles can withstand high levels of isometric stress, displaying a stress of 61 times that of skeletal muscles and 8 times that of “rocking-chair” type yarn muscles at higher frequencies. This technology holds significant potential for various applications, including prosthetics and robotics.

Functionalization of carbon nanotube yarn by acid treatment

Carbon nanotube(CNT)yarn was functionalized using sulfuric and nitric acid solutions in 3:1 volumetric ratio.Successful functionalization of CNT yarn with carboxyl and hydroxyl groups(e.g.,COOH,COO–,OH,etc.)was confirmed by attenuated total reflectance spectroscopy.X-ray diffraction revealed no significant change to the atomic in-plane alignment in the CNTs;however,the coherent length along the diameter was significantly reduced during functionalization.A morphology change of wavy extensions protruding from the surface was observed after the functionalization treatment.The force required to fracture the yarn remained the same after the functionalization process;however,the linear density was increased(310%).The increase in linear density after functionalization reduced the tenacity.However,the resistivity density product of the CNT yarn was reduced significantly(234%)after functionalization.

Intrafascicular Vagal Activity Recording and Analysis Based on Carbon Nanotube Yarn Electrodes

The vagus nerve carries sensory information from multiple organs in the body.The recording of its activity and further processing is a key step for neuromodulation treatments.This paper presents a specific algorithm for the processing and discrimination of intrafascicular recordings from the vagus nerve using the novel carbon nanotube yarn electrodes.Up to four different neural waveforms were found,whose occurrence corresponded to distinct levels of anesthesia depth.

Blood Pressure Change in Intrafascicular Vagal Activities

Baroreflex plays a significant role in modulating blood pressure for the human body.It is known that activation of the vagal nerve related to baroreflex can lead to reductions of blood pressure.However,how the vagal activities quantitatively relate with blood pressure can hardly be achieved.Here fine carbon nanotube yarn(CNTy)electrodes were adopted for recording intrafascicular vagal activities,synchronized with measurement of arterial blood pressure in a rat.Together with a novel algorithm,the results preliminarily quantified that there were six clusters of neural spikes within recorded vagal activities,and the number of individual vagal spikes correspondingly varied with blood pressure.Especially for Cluster 2,the neural activations decreased with arterial blood pressure increasing.This study can shed lights on the quantified neural mechanism underlying the control of vagal activities on blood pressure,and guide the vagal-nerve neuromodulation for treating hypertension.