Tailoring viscoelastic response of carbon nanotubes cellular structure using electric field

Recent advances in self-actuation and self-sensing materials: State of the art and future perspectives

The contradiction between human's strong demand of fossil fuels and their limited reserves becomes increasingly severe. Without external power input, intelligent materials responding sharply and reversibly to various external stimuli are the topic of intense research these years, especially the self-actuation and self-sensing materials. The promising family of these materials will play a significant role in energy-saving, low-cost and environment-friendly intelligent systems in the future. This review summarizes the latest advances in self-actuation and self-sensing materials. The synthetic strategies, morphologies and performance of these materials are introduced, as well as their applications in energy harvest, self-powering sensors, wearable devices, etc. Finally, tentative conclusions and assessments regarding the opportunities and challenges for the future development of these materials are presented.

Capacitive behavior of carbon nanotube thin film induced by deformed ZnO microspheres

Multiwalled carbon nanotubes (CNTs) are uniformly distributed with piezoelectric microspheres. This leads to a large strain gradient due to an induced capacitive response, providing a 250% enhancement in electromechanical response compared with pristine CNTs. The fabricated large-area flexible thin film exhibits excellent pressure sensitivity, which can even detect an arterial pulse with a much faster response time (∼79 ms) in a bendable configuration. In addition, the film shows a rapid relaxation time (∼0.4 s), high stability and excellent durability with a rapid loading-unloading cycle. The dominant contribution of piezoelectric microspheres in a CNT matrix as opposed to nanoparticles showed a much higher sensitivity due to the large change in capacitance. Therefore, hybrid microstructures have various potential applications in wearable smart electronics, including detection of human motion and wrist pulses.

Effect of electric field on creep and stress-relaxation behavior of carbon nanotube forests

Carbon nanotube forests (CNTFs) are porous ensembles of vertically aligned carbon nanotubes, exhibiting excellent reversible compressibility and electric field tunable stress–strain, creep, and viscoelastic responses.

Giant actuation in bulk carbon nanotubes under coupled electric and magnetic fields

The transformation of electrostrictive to piezoelectric behavior is observed in carbon nanotube under coupled electro-magnetic field. Five times higher actuation response was observed under coupled field as compared to the individual fields.

Evaluating shock absorption behavior of small-sized systems under programmable electric field

A simple ball-drop impact tester is developed for studying the dynamic response of hierarchical, complex, small-sized systems and materials. The developed algorithm and set-up have provisions for applying programmable potential difference along the height of a test specimen during an impact loading; this enables us to conduct experiments on various materials and smart structures whose mechanical behavior is sensitive to electric field. The software-hardware system allows not only acquisition of dynamic force-time data at very fast sampling rate (up to 2 × 10(6) samples/s), but also application of a pre-set potential difference (up to ±10 V) across a test specimen for a duration determined by feedback from the force-time data. We illustrate the functioning of the set-up by studying the effect of electric field on the energy absorption capability of carbon nanotube foams of 5 × 5 × 1.2 mm(3) size under impact conditions.