Recent research progress of relieving discomfort between electronics and human body involves serpentine designs, ultrathin films, and extraordinary properties of nanomaterials. However, these strategies addressed thus far each face own limitation for achieving desired form of electronic-skin applications. Evenly matched mechanical properties anywhere on the body and imperceptibility of electronics are two essentially required characteristics for future electronic-skin (E-skin) devices. Yet accomplishing these two main properties simultaneously is still very challenging. Hence, we propose a novel fabrication method to introduce kirigami approach to pattern a highly conductive and transparent electrode into diverse shapes of stretchable electronics with multivariable configurability for E-skin applications. These kirigami engineered patterns impart tunable elasticity to the electrodes, which can be designed to intentionally limit strain or grant ultrastretchability depending on applications over the range of 0 to over 400% tensile strain with strain-invariant electrical property and show excellent strain reversibility even after 10 000 cycles stretching while exhibiting high optical transparency (>80%). The versatility of this work is demonstrated by ultrastretchable transparent kirigami heater for personal thermal management and conformal transparent kirigami electrophysiology sensor for continuous health monitoring of human body conditions. Finally, by integrating E-skin sensors with quadrotor drones, we have successfully demonstrated human-machine-interface using our stretchable transparent kirigami electrodes.

A DNA tetrahedron is employed for efficient delivery of doxorubicin into drug-resistant breast cancer cells. The drug delivered with the DNA nanoconstruct is considerably cytotoxic, whereas free doxorubicin is virtually non-cytotoxic for the drug-resistant cells. Thus, the DNA tetrahedron, made of the inherently natural and biocompatible material, can be a good candidate for the drug carrier to overcome MDR in cancer cells.

Ionic liquid (IL) modified reduced graphene oxide (rGO-IL) nanosheets anchoring manganese oxide (Mn 3 O 4 ) are synthesized via a facile solution-based growth mechanism and applied to a Zn-air battery as an effective electrocatalyst for the oxygen reduction reaction (ORR). In this study, the IL moiety in these composites increases not only the conductivity of the system, but also the electrocatalytic activity compared to pristine rGO, together with the synergic effect of facilitating the ORR with the intrinsic catalytic activity of Mn 3 O 4 . Based on the Koutecky-Levich plot, we suggest that the ORR pathway of these composites is tunable with the relative amount of Mn 3 O 4 nanoparticles supported onto the graphene sheets; for example, the ORR mechanism of the system with a lower Mn 3 O 4 (19.2%) nanoparticle content is similar to a Pt/C electrode, i.e., a one-step, quasi-4-electron transfer, unlike that with a higher Mn 3 O 4 (52.5%) content, which undergoes a classical two-step, 2-electron pathway. We also demonstrate the potential of these hybrid rGO-IL/Mn 3 O 4 nanoparticles as efficient catalysts for the ORR in the Zn-air battery with a maximum peak power density of 120 mW cm À2 ; a higher performance than that from commercial cathode catalysts.

graphene sheets have become a versatile platform for the fabrication of innovative hybrid materials with various functions due to their unique electrical, optical, thermal, and mechanical properties. The preparation of graphene-based composites with nanoscale precision is highly important for reproducible and controllable performance through the analysis of interplay between each component. In particular, the layer-by-layer (LbL) assembly technique is known as a simple, inexpensive, and versatile process for the fabrication of highly ordered multilayer film structures from various types of materials. The LbL structures capable of controlling nanoscale composition and architectures are achieved through the sequential adsorption of oppositely charged components by attractive forces such as electrostatic interactions. In this review, we will focus on the recent progress in graphene-based nanocomposites hybridized with various nanomaterials such as carbon nanomaterials, polymers, and inorganic nanoparticles by the LbL assembly. Multilayered graphene nanocomposites exhibit improved physical/chemical properties and superior performance compared with the individual components due to the synergistic effects in various applications including electric devices, energy storage and conversion, and biological usages.

A hybrid electrode consisting of an electric double-layer capacitor of graphene nanosheets and a pseudocapacitor of the conducting polymer polyaniline exhibits a synergistic effect with excellent electrochemical performance for flexible thin film supercapacitors. This hybrid supercapacitor is constructed by a nanoscale blending method of layer-by-layer (LbL) assembly based on the electrostatic interactions between positively charged polyaniline (PANi) and negatively charged graphene oxide (GO) nanosheets. The hybrid electrode provides not only improved electronic conductivity through the intimate contact with the graphene nanosheet, but also enhanced chemical stability during the charge-discharge process. We also investigated the dependence of the electrochemical performance on the various parameters of LbL assembly such as the number of bilayers and the post-thermal and chemical treatments that could affect the degree of reduction of GO and PANi. We found that after thermal treatment, the LbL-assembled thin film of PANi with GO nanosheets exhibited an excellent gravimetric capacitance of 375.2 F g À1 at a discharge current density of 0.5 A g À1 that outperformed many other hybrid supercapacitors reported to date. The hybrid supercapacitor maintained its capacity up to 90.7% over 500 cycles at a high current density of 3.0 A g À1 . This study opens up the possibility for the production of diverse graphene-based hybrid nanocomposites that are promising for future flexible supercapacitors.

Smart fabrics and interactive textiles have attracted great interest as a newly emergent material because of their multifunctional capabilities. Herein, a highly robust wireless flexible strain sensor on the basis of commercial textile by the integration of functional hybrid carbon nanomaterials and piezoresistive material is fabricated. Specifically, a solution‐processable spray‐assisted coating approach that enables the creation of a uniform coating over a large area of fabrics is employed. The textile‐based strain sensor exhibits a highly stable and immediate response over a wide range of bending curvatures and structural properties of ZnO nanowires because of their different deflection behaviors. The wearing performance with attaching on commercial fabrics is further demonstrated. The as‐prepared sensor responds well to diverse body motions with accurate detection of strain magnitude and even extends its viability in wireless remote sensing by connecting to a wireless transmitter. The novel approach for the modification of textiles with functional nanomaterials may provide a feasible approach for the production of textile‐based electronics without employing any sophisticated fabrication processes, and it further exploits the diverse functionalities by utilizing various sensing components.

Recently, a mechanical crack-based strain sensor with high sensitivity was proposed by producing free cracks via bending metal coated film with a known curvature. To further enhance sensitivity and controllability, a guided crack formation is needed. Herein, we demonstrate such a ultra-sensitive sensor based on the guided formation of straight mechanical cracks. The sensor has patterned holes on the surface of the device, which concentrate the stress near patterned holes leading to generate uniform cracks connecting the holes throughout the surface. We found that such a guided straight crack formation resulted in an exponential dependence of the resistance against the strain, overriding known linear or power law dependences. Consequently, the sensors are highly sensitive to pressure (with a sensitivity of over 1 × 105 at pressures of 8–9.5 kPa range) as well as strain (with a gauge factor of over 2 × 106 at strains of 0–10% range). A new theoretical model for the guided crack system has been suggested to be in a good agreement with experiments. Durability and reproducibility have been also confirmed.

Sensors to detect motion with high precision have been extensively studied in diverse engineering research fields.