Carbon nanotubes (CNTs), owing to their superior electrical and mechanical properties, are a promising alternative to nonmetallic electrically conducting materials. In practice, cellulose as a low‐cost sustainable matrix has been used to prepare the aqueous dispersion of cellulose‐CNT (C‐CNT) nanocomposites. However, the compatibility with conventional solution‐processing and structural rearrangement for improving conductivity has yet to be determined. Herein, a straightforward route to prepare a conductive composite material from single‐walled CNTs (SWCNTs) and natural pulp is reported. High‐power shaking realizes the self‐alignment of individual SWCNTs in a cellulose matrix, resulting from the structural change in molecular orientations owing to countless collisions of zirconia beads in the aqueous mixture. The structural analysis of the dried C‐CNT films confirms that the entanglement and dispersion of C‐CNT nanowires determine the mechanical and electrical properties. Moreover, the rheological behavior of C‐CNT inks explains their coating and printing characteristics. By controlling shaking time, the electrical conductivity of the C‐CNT films with only 9 wt.% of SWCNTs from 0.9 to 102.4 S cm−1 are adjusted. the optimized C‐CNT ink is highly compatible with the conventional coating and printing processes on diverse substrates, thus finding potential applications in eco‐friendly, highly flexible, and stretchable electrodes is also demonstrated.
As the number of patients with amputations increases, research on assistive devices such as prosthetic limbs is actively being conducted. However, the development of assistive devices for patients with partial amputations is insufficient. In this study, we developed a finger prosthesis for patients with partial amputations. The design and mathematical modeling of the prosthesis are briefly presented. A pneumatic actuator, based on the McKibben muscle design, was employed to drive the finger prosthesis. We characterized the relationship between the actuator’s force and axial length changes with varying pressure. An empirical model derived from conventional mathematical modeling of force and axis length changes was proposed and compared with experimental data, and the error was measured to be between about 3% and 13%. In order to control the actuator using an electromyography (EMG) signal, an electrode was attached to the user’s finger flexors. The EMG signal was measured in relation to the actual gripping force and was provided with visual feedback, and the magnitude of the signal was evaluated using root mean square (RMS). Depending on the evaluated EMG signal magnitude, the pressure of the actuator was continuously adjusted. The pneumatic pressure was adjusted between 100 kPa and 250 kPa, and the gripping force of the finger prosthesis ranged from about 0.7 N to 6.5 N. The stiffness of the prosthesis can be varied using the SMA spring. The SMA spring is switched to a fully austenite state at 50 °C through PID control, and when the finger prosthesis is bent to a 90° angle, it can provide approximately 1.2 N of assistance force. Finally, the functional evaluation of the finger prosthesis was performed through a pinch grip test of eight movements.
Products are manufactured as printed electronics through electro-conductive ink having properties suitable for flexible substrates. As printing process conditions affect the quality of the electronic properties of the final devices, it is essential to understand how the parameters of each process affect print quality. Spray printing, one of several printing processes, suits flexible large-area substrates and continuous processes with a uniform layer for electro-conductive aqueous ink. This study adopted the spray printing process for cellulose nanofiber (CNF)/carbon nanotube (CNT) composite conductive printing. Five spray parameters (nozzle diameter, spray speed, amount of sprayed ink, distance of nozzle to substrate, and nozzle pressure) were chosen to investigate the effects between process parameters and electrical properties relating to the morphology of the printing products. This study observed the controlling morphology through parameter adjustment and confirmed how it affects the final electrical conductivity. It means that the quality of the electronic properties can be modified by adjusting several spray process parameters.
The unique biological features of supramolecular DNA have led to an increasing interest in biomedical applications such as biosensors. We have developed an i-motif and G-rich DNA conjugated single-walled carbon nanotube hybrid materials, which shows reversible conformational switching upon external stimuli such as pH (5 and 8) and presence of ions (Li+ and K+). We observed reversible electrochemical redox activity upon external stimuli in a quick and robust manner. Given the ease and the robustness of this method, we believe that pH- and ion-driven reversible DNA structure transformations will be utilized for future applications for developing novel biosensors.
Array tomography using scanning electron microscopy (SEM) enables large-volume, nanometer-scale reconstruction of neural circuits and allows nanometer resolution of synaptic vesicles and other ultrastructural features. For stable serial imaging, Kapton tape, carbon nanotube (CNT) tape mounted on silicon wafers, and indium tin oxide (ITO) glass have commonly been used. However, each tape shows practical limitations: CNT tape is not consistently available, whereas Kapton tape often requires additional glow discharge or carbon coating steps to reduce charging artifacts and improve imaging stability. Here, we report the development of a lab-made tape using a cellulose/CNT/AgNW composite tape designed for SEM-based array tomography. By integrating intrinsically hydrophilic natural cellulose fibrils with conductive carbon or silver nanotubes, the newly developed tape provides sufficient surface hydrophilicity and conductivity without additional glow discharge or carbon coating treatment. This simplifies workflow while maintaining stable imaging conditions. Notably, the cellulose fibrils containing tape demonstrated reduced charging artifacts, improved section adhesion, and stable high-resolution imaging suitable for nanometer level analysis. Our results establish cellulose-based conductive tape as a practical advancement for array tomography, enhancing reliability and reproducibility in large-scale SEM imaging.