Fast Peel-Off Ultrathin, Transparent, and Free-Standing Films Assembled from Low-Dimensional Materials Using MXene Sacrificial Layers and Produced Bubbles

Ultrathin, transparent, and free-standing films assembled from low-dimensional nanomaterials (LDMs) are promising for various applications, including transparent heaters and membranes. However, the intact separation of the assembled films, especially those with controlled ultrathin thickness from deposited substrates, is a tremendous challenge, particularly for fast peeling off via self-detaching. Herein, we propose a versatile method to rapidly peel off ultrathin assembled LDM films, including three types of carbon nanotubes, vermiculite, Ag nanowires, and carbon nanotube@graphene, by dissolving the MXene interlayer from the layer-by-layer filtered MXene/LDM Janus films using diluted H₂ O₂ . The MXene sacrificial interlayers play dual roles, including physical isolation of LDM films from filter membranes and the production of bubbles that buoy ultrathin LDM films, making them free-standing. The integrality and self-detaching rate of the LDM films are determined by the loading and reactivity of the MXene interlayers. The intact LDM films can self-detach in 80 s by dissolving the optimized MXene interlayer and producing bubbles. The as-made free-standing ultrathin LDM films can be transferred to arbitrary substrates and exhibit outstanding performance as transparent heaters. This scalable method provides an efficient and versatile method to produce ultrathin, transparent, and free-standing LDM films and finds new applications for the growing MXene family.

Pharmaceutical Perspective in Wearable Drug Delivery Systems

Humans have been dealing with health problems for millions of years. Normal health services need well-trained personnel and high-cost diagnostic tests, which forces patients to go to hospitals if medical treatment is required. To address this, prototype testing has been carried out into the wearable drug delivery health care perspectives. Researchers have devised a wide variety of formulations for the treatment of various diseases at home by performing real-time monitoring of different routes of drug administration such as ocular, transdermal, intraoral, intracochlear, and several more. A comprehensive review of the different types of wearable drug delivery systems with respect to their manufacturing, mechanism of action and specifications has been done. In the pharmaceutical context, these devices are technologically well-equipped interfaces for diverse physicochemical signals. Above mentioned information with a broader perspective has also been discussed in this article. Several wearable drug delivery systems have been introduced in the market in recent years. But a lot of testing needs to be conducted to address the numerous obstacles before the wearable devices are successfully launched in the market.

Laser-Induced Graphene Paper Heaters with Multimodally Patternable Electrothermal Performance for Low-Energy Manufacturing of Composites

Low-energy manufacturing of polymeric composites through two-dimensional electrothermal heaters is a promising strategy over the traditional autoclave and oven. Laser-induced graphene paper (LIGP) is a recent emergent multifunctional material with the merits of one-step computer aided design and manufacturing (CAD/CAM) as well as a flexible thin nature. To fully explore its capabilities of in situ heating, herein, we adventurously propose and investigate the customizable manufacture and modulation of LIGP enabled heaters with multimodally patternable performance. Developed by two modes (uniform and nonuniform) of laser processing, the LIGP heaters (LIGP-H) show distinctively unique characteristics, including high working range (>600 °C), fast stabilization (<8 s), high temperature efficiency (∼370 °C·cm²/W), and superb robustness. Most innovatively, the nonuniform processing could section LIGP-H into subzones with independently controlled heating performance, rendering various designable patterns. The above unique characteristics guarantee the LIGP-H to be highly reliable for in situ curing composites with flat, curved, and even inhomogeneous structures. With enormous energy-savings (∼85%), superb curing accuracy, and comparable mechanical strength, the proposed device is advantageous for assuring high-quality and highly efficient manufacturing.

Highly Stretchable Multifunctional Wearable Devices Based on Conductive Cotton and Wool Fabrics

The demand for stretchable, flexible, and wearable multifunctional devices based on conductive nanomaterials is rapidly increasing considering their interesting applications including human motion detection, robotics, and human-machine interface. There still exists a great challenge to manufacture stretchable, flexible, and wearable devices through a scalable and cost-effective fabrication method. Herein, we report a simple method for the mass production of electrically conductive textiles, made of cotton and wool, by hybridization of graphene nanoplatelets and carbon black particles. Conductive textiles incorporated into a highly elastic elastomer are utilized as highly stretchable and wearable strain sensors and heaters. The electromechanical characterizations of our multifunctional devices establish their excellent performance as wearable strain sensors to monitor various human motions, such as finger, wrist, and knee joint movements, and to recognize sound with high durability. Furthermore, the electrothermal behavior of our devices shows their potential application as stretchable and wearable heaters working at a maximum temperature of 103 °C powered with 20 V.

Recent Advances in Wearable Transdermal Delivery Systems

Wearable transdermal delivery systems have recently received tremendous attention due to their noninvasive, convenient, and prolonged administration of pharmacological agents. Here, the material prospects, fabrication processes, and drug-release mechanisms of these types of therapeutic delivery systems are critically reviewed. The latest progress in the development of multifunctional wearable devices capable of closed-loop sensation and drug delivery is also discussed. This survey reveals that wearable transdermal delivery has already made an impact in diverse healthcare applications, while several grand challenges remain.

Stretchable and Energy-Efficient Heating Carbon Nanotube Fiber by Designing a Hierarchically Helical Structure

Inspired by the hierarchically helical structure of classical thermal insulation material-wool, a stretchable heating carbon nanotube (CNT) fiber is created with excellent mechanical and heating properties. It can be stretched by up to 150% with high stability and reversibility, and a good thermal insulation is achieved from a large amount of formed hierarchically helical voids inside. Impressively, it exhibits ultrafast thermal response over 1000 °C s^-1 , low operation voltage of several volts, and high heating stability over 5000 cycles. These hierarchically helical CNT fibers, for the first time, are demonstrated as monofilaments to produce soft and lightweight textiles at a large scale with high heating performances.

Screen-Printed Fabrication of PEDOT:PSS/Silver Nanowire Composite Films for Transparent Heaters

A transparent and flexible film heater was fabricated; based on a hybrid structure of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and silver nanowires (Ag NWs) using a screen printing; which is a scalable production technology. The resulting film integrates the advantages of the two conductive materials; easy film-forming and strong adhesion to the substrate of the polymer PEDOT:PSS; and high conductivity of the Ag NWs. The fabricated composite films with different NW densities exhibited the transmittance within the range from 82.3% to 74.1% at 550 nm. By applying 40 V potential on the films; a stable temperature from 49 °C to 99 °C was generated within 30 s to 50 s. However; the surface temperature of the pristine PEDOT:PSS film did not increase compared to the room temperature. The composite film with the transmittance of 74.1% could be heated to the temperatures from 41 °C to 99 °C at the driven voltages from 15 V to 40 V; indicating that the film heater exhibited uniform heating and rapid thermal response. Therefore; the PEDOT:PSS/Ag NW composite film is a promising candidate for the application of the transparent and large-scale film heaters.

Surficial nanoporous carbon with high pyridinic/pyrrolic N-Doping from sp3/sp2-N-rich azaacene dye for lithium storage

Dye to carbon: Two rationally designed pyridinic/pyrrolic N-doped porous carbons as anodic materials could be achieved by carbonizing π-conjugated azaacene dye born with high ratio sp³/sp²-N.

High-Performance Multiresponsive Paper Actuators

There is an increasing demand for soft actuators because of their importance in soft robotics, artificial muscles, biomimetic devices, and beyond. However, the development of soft actuators capable of low-voltage operation, powerful actuation, and programmable shape-changing is still challenging. In this work, we propose programmable bilayer actuators that operate based on the large hygroscopic contraction of the copy paper and simultaneously large thermal expansion of the polypropylene film upon increasing the temperature. The electrothermally activated bending actuators can function with low voltages (≤ 8 V), low input electric power per area (P ≤ 0.14 W cm^-2), and low temperature changes (≤ 35 °C). They exhibit reversible shape-changing behavior with curvature radii up to 1.07 cm^-1 and bending angle of 360°, accompanied by powerful actuation. Besides the electrical activation, they can be powered by humidity or light irradiation. We finally demonstrate the use of our paper actuators as a soft gripper robot and a lightweight paper wing for aerial robotics.