We developed a 3D solar steam generator with the highest evaporation rate reported so far using a carbonized luffa sponge (CLS). The luffa sponge consisted of entangled fibers with a hierarchically porous structure; macropores between fibers, micro-sized pores in the fiber-thickness direction, and microchannels in the fiber-length direction. This structure remained after carbonization and played an important role in water transport. When the CLS was placed in the water, the microchannels in the fiber-length direction transported water to the top surface of the CLS by capillary action, and the micro-sized pores in the fiber-thickness direction delivered water to the entire fiber surface. The water evaporation rate under 1-sun illumination was 3.7 kg/m2/h, which increased to 14.5 kg/m2/h under 2 m/s wind that corresponded to the highest evaporation rate ever reported under the same condition. The high evaporation performance of the CLS was attributed to its hierarchically porous structure. In addition, it was found that the air temperature dropped by 3.6 °C when the wind passed through the CLS because of the absorption of the latent heat of vaporization. The heat absorbed by the CLS during water evaporation was calculated to be 9.7 kW/m2 under 1-sun illumination and 2 m/s wind, which was 10 times higher than the solar energy irradiated on the same area (1 kW/m2).

Rapid and sensitive detection of pathogenic bacteria in various samples, including food and drinking water, is important to prevent bacterial diseases. Most bacterial solutions contain only a small number of bacteria in complex matrices with impurities; hence, pretreatment is necessary to separate and concentrate target bacteria before sensing. Among various pretreatment methods, iron oxide magnetic nanoparticle (MNP)-based pretreatment has drawn attention owing to the unique properties of MNP, such as high magnetic susceptibility, superparamagnetism, and biocompatibility. After target bacteria are captured by recognition molecule-functionalized MNPs, bacteria–MNP complexes can be easily separated and enriched by applying an external magnetic field. Various devices, such as optical, electrochemical, and magnetoresistance sensors, can be used to detect target bacteria, and their detection principles have been discussed in numerous review papers. Herein, we focus on recent research advances and challenges in magnetic pretreatment of pathogenic bacteria using microfluidic devices, which offer the advantages of process automation and miniaturization.

desalination aims to efficiently produce as much fresh water as possible from seawater, both solar evaporation (occurring only during the day) and dark evaporation (occurring even at night) must be improved simultaneously.The total evaporation rate of conventional 2D-structured SSG (2D-SSG) can be improved by adopting 3D-structured SSG (3D-SSG), which uses environmental energy more efficiently. [35][36][37][38][39][40][41][42][43][44][45][46] Wood-based 3D-SSG is attracting considerable attention because wood is sustainable, environmentally friendly, and abundant. Furthermore, wood has many advantages promoting the efficiency of SSG, such as low thermal conductivity (i.e., high thermal insulation) and well-developed natural water channels for vertical water transport. [47][48][49][50] However, vertical water transport through natural water channels becomes insufficient, as the height of a wood evaporator increases. Vertical water transport in 3D-SSG can be improved by increasing hydrophilicity and capillary forces, [51,52] or by fabricating the macrochannels such as interlayer spaces or millimeter-sized holes. [30,53,54] However, these methods have a limited effect on improving lateral water transport to the side surface, where dark evaporation mostly occurs. In contrast to vertical water transport, lateral water transport occurs along complex pathways connected by microchannels with a few micrometers in diameter, which limits the water supply in the radial direction. If the supply of seawater to the vaporizing surface is insufficient, the evaporation performance will decrease and salt may accumulate. These problems can be addressed by creating additional water channels in the radial direction. However, generating a sufficient number of channels to supply water all over the side surface is difficult, and production of excessive wood waste is inevitable.In this study, we developed an evaporator in the form of a scroll and demonstrated its excellent performance as an all-day steam generator. When a thin wood veneer with natural water channels that were parallel or diagonal to the layer direction was rolled into a scroll, gap channels were created between the overlapping wood layers. Vertical water transport through these gap channels was >10 times higher than that through natural water channels. Diagonal channels greatly enhanced lateral water transport across the wood layer compared to microchannels. The synergy between the gap channels and the diagonal natural water channels simultaneously increased dark evaporation and salt resistance. The water evaporation rate was 9.08 kg m −2 h −1 in the absence of wind but increased to 37.95 kg m −2 h −1 in the presence of 2 m s −1 wind, which are among the highest values ever reported under similar conditions. A novel all-day evaporator in the form of a scroll is developed by rolling a thin layer of wood. Two different wood layers are used to fabricate a wood scroll with diagonal natural water channels (d-WS) and a wood scroll with parallel natural water channels (p-WS). Be...

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