Microsupercapacitors have attracted significant attention due to several of their advantageous characteristics such as lightweight, small volume, and planar structure that is favorable for high mechanical flexibility. Among the various micro supercapacitor forms, those with laser-induced graphene (LIG) electrodes are promising as flexible energy storage devices. While LIG microelectrodes can be fabricated simply by direct laser writing, the capacitance and energy density of these devices are limited because of the relatively low density of LIG, which leads to low surface areas. These limitations could be overcome by densifying the LIG. Here, we report the use of densified laser-induced graphene (d-LIG) to fabricate flexible micro supercapacitors. Interdigitated d-LIG electrodes were prepared by duplicate laser pyrolysis of a polyimide sheet by using a CO2 laser. A PVA-H2SO4 gel-type electrolyte was then applied to the d-LIG electrode surface to assemble a d-LIG micro supercapacitor. This d-LIG micro supercapacitor exhibited substantially increased capacitance and energy density versus conventional low-density LIG micro supercapacitors. While the d-LIG electrode exhibited a substantial change in resistance when subjected to bending at a radius of 3 mm, the change in the capacitance of the d-LIG micro supercapacitor was negligible at the same bending radius due to reinforcement by the infiltrated poly(vinyl alcohol) (PVA) electrolyte, demonstrating the potential application of d-LIG micro supercapacitors in wearable electronics.

The attachment of microbial biomass on solid surfaces, also referred to as biofouling, is a universal phenomenon that occurs in natural and engineering systems. However, traditional antibiofouling surfaces based on either the release of biocidal compounds or surface chemical/physical design have some drawbacks, such as the high cost, the complicated process, the low accuracy, and the limitation to achieve coatings over large area. Herein, to overcome these problems, a superhydrophobic coating is fabricated via spraying the mixture of hydrophobized zinc oxide nanoparticles and epoxy resin. The zinc oxide nanoparticles form a multiscale roughness, and the epoxy resin promotes the robustness of the coating. The so-formed superhydrophobic coating resists the attachment of protein, bacteria, and marine algae. It is expected that the so-developed superhydrophobic coating can be applied in the fields of biomedical instruments, antimicrobial material, marine platform, and ships.

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Conductive fibers are essential building blocks for implementing various functionalities in a textile platform that is highly conformable to mechanical deformation. In this study, two major techniques were developed to fabricate silver-deposited conductive fibers. First, a droplet-coating method was adopted to coat a nylon fiber with silver nanoparticles (AgNPs) and silver nanowires (AgNWs). While conventional dip coating uses a large ink pool and thus wastes coating materials, droplet-coating uses minimal quantities of silver ink by translating a small ink droplet along the nylon fiber. Secondly, the silver-deposited fiber was annealed by similarly translating a tubular heater along the fiber to induce sintering of the AgNPs and AgNWs. This heat-scanning motion avoids excessive heating and subsequent thermal damage to the nylon fiber. The effects of heat-scanning time and heater power on the fiber conductance were systematically investigated. A conductive fiber with a resistance as low as ~2.8 Ω/cm (0.25 Ω/sq) can be produced. Finally, it was demonstrated that the conductive fibers can be applied in force sensors and flexible interconnectors.

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