No abstract

No abstract

Laser-induced graphene (LIG) has garnered tremendous attention in the past decade as a flexible, scalable, and patternable alternative for fabricating electronic sensors. Superhydrophobic and superhydrophilic variants of LIG have been demonstrated by previous studies. However, stability analysis of the superhydrophobic surface property has not been explored. In this study, we use an infrared nanosecond laser to fabricate reduced graphene oxide (rGO)-based strain sensor on a carbon fiber reinforced polymer (CFRP) composite substrate. The fabricated sensor is characterized to determine its gauge factor using a three-point bend test demonstrating a gauge factor of 40. The fabricated LIG exhibits excellent superhydrophobic properties with a high contact angle (>160°). Both superhydrophobicity and piezoresistivity of the LIG under water immersion are studied for 25 h, demonstrating high stability. The obtained results could be of interest to several sectors, especially for maritime and high humidity applications.

Capillarity is omnipresent in nature, being directly involved in the functioning of living systems. [1] Natural porous media can be characterized by stochastic (e.g., soil, sponges) or ordered (e.g., wood, lungs) structures. Their manmade counterparts are numerous and widely adopted in most industries, for instance filters, textiles (woven and nonwoven), absorbents, ceramics, or tissue scaffolds. [2] Engineering the capillary properties of porous materials has been pursued to achieve improved thermal, [3] mechanical, [4] electrical, [5] optical, [6] and biomedical [7] performance. In addition to intrinsically porous materials (e.g., metal organic frameworks [8] ), the recent research has focused on manufacturing processes that can control finely either material addition (e.g., 3D printing [1,9] ) or removal (e.g., laser etching [6,10] ) from bulk materials to design a precise pores architecture.Porous materials with engineered multi-functionalities are particularly desirable for passive energy-conversion devices. These devices typically do not require high quality energy inputs and, due to the absence of moving mechanical parts, require low maintenance, and are cost-effective. Moreover, they are optimal for off-grid installations and, in general, promote the sustainable transition of industries related to the water-energy nexus. [11] These devices can exploit porous capillary media to overcome small hydraulic heads and supply the working fluids throughout the system without the need for active mechanical or electrical components. Applications have been proposed for steam generation, [12] desalination, [13,14] salt precipitation, [15] water sanitation, [16] solar thermal energy harvesting, [6] and cooling, [17] among others. Clearly, optimizing the capillary properties of the porous materials in such passive devices is crucial to enhance their overall performance: poor capillarity may lead to dry-out during continuous evaporative processes, and would significantly limit the maximum achievable device size. [18] Thus, sub-optimal capillary properties would significantly hinder the productivity and scalability of the system overall.Passive energy-conversion devices typically use nonstructured capillary materials, such as paper or commercial textiles, as passive component to move working fluids. [19] These materials, however, offer limited degrees of optimization given Passive energy-conversion devices based on water uptake and evaporation offer a robust and cost-effective alternative in a wide variety of applications. This work introduces a new research avenue in the design of passive devices by replacing traditional porous materials with rigid capillary layers engraved with optimized V-shaped grooves. The concept is tested using aluminum sheets, which are machined by femtosecond laser and covered by silica or functionalized by oxygen plasma to achieve stable long-term capillary properties. The durability of the proposed material is experimentally evaluated when functioning with aqueous salt concentrations: both the ...