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Droplet manipulation is of paramount significance for microfluidics-based biochips, especially for bioanalytical chips. Despite great progresses made on droplet manipulation, the existing bioanalytical methods face challenges in terms of capturing minute doses toward hard-to-obtain samples and analyzing biological samples at low temperatures immediately. To circumvent these limitations, a self-propelled and electric stimuli synergetic droplet manipulator (SES-SDM) was developed by a femtosecond laser microfabrication strategy followed by post-treatment. Combining the inspiration from cactus and Nepenthes pitcher plants, the wedge structure with the microbowl array and silicone oil infusion was endowed cooperatively with the SES-SDM. With the synergy of the ultralow voltage (4.0 V) stimuli, these bioinspired features enable the SES-SDM to transport the droplet spontaneously and controllably, showing the maximum fast motion (15.7 mm/s) and long distance (96.2 mm). Remarkably, the SES-SDM can function at -5 °C without the freezing of the droplets, where the self-propelled motion and electric-responsive pinning can realize the accurate capture and real-time analysis of the microdroplets of the tested samples. More importantly, the SES-SDM can realize real-time diagnosis of excessive heavy metal in water by the cooperation of self-propulsion and electro-brake. This work opens an avenue to design a microsampling (5-20 μL) manipulator toward producing the minute samples for efficient bioanalysis and offers a strategy for microanalysis using the synergistic droplet manipulation.

Bioinspired functional structures or devices show great potential for harvesting water resources in the atmosphere. Despite the great advances made in the capture and transportation of the droplets, the efficient storage of harvested water for direct and cyclable utilization is rarely concerned towards real daily life. Inspired by the long-stem storage of water caused from the Triarrhena sacchariflora leaf sheath, a wearable fogdrop collector was developed via laser structuring and origami techniques for effectively nourishing the plants in a lower-evaporation condition. The collector shows an annular thin-wall with a superhydrophilic grooved inwall (SGI), and a circular array of spine with thorns and gradient channels (STGCs). These structural features enable the collector to capture fogdrop by STGC, and keep water inside the thin-wall for long-lasting moisture retention. Furthermore, due to the excellent flexibility and composability, multiple collectors can be easily assembled to a larger harvesting one, implying its scalability potential. The assembled devices show a higher collection efficiency and lower evaporation than the individual ones, reaching ∼8.4 mL per hour when using triple collectors. More interestingly, such devices can be directly used for the moisture retention of the fresh flower, showing water retention of more than 140 min, which is superior to the traditional watering or water spraying. This work gives a flexible design strategy of a portable scalable collector for water harvesting, and especially opens an avenue to the direct and actual utilization of the fogdrop collectors for the flower moisture retention and even agricultural irrigation.

Despite extensive efforts made in directional manipulation of water and oil microdroplets, challenges still remain in the ultrafast self-transportation and the rapid separation of droplets with different surface tensions due to the lack of driving force. The natural inspiration from fish medullary spines provides a potential way to realize directional oil movement by using an anisotropic surface with micropits. Herein, a fish-spine-like liquid splitter (FSLLS) is developed based on a precise 3D printing and subsequent femtosecond laser structuring. The liquid splitter enables directional transportation of various microdroplets, with the maximum velocity reaching 265.3 mm s−1. More interestingly, it can spontaneously transport liquids with the surface tension ranging from 15 to 48 mN m−1, achieving an outstanding selectivity of specific liquids. Moreover, the lower the surface tension for the liquid in the surface tension range, the faster the transport speed on the FSLLS. This feature can be attributed to the unique micro-pit structure on the FSLLS surface and its oleophilic properties. The combination of ultrafast directional transportation and peculiar selective ability makes the FSLLS achieve the pumping of microdroplets with lower surface tension. As a proof-of-concept, the separation of the mixed droplets with different surface tensions is demonstrated using the FSLLS and the scalable device. This study offers a new bionic design concept for selective microdroplet pumping devices and opens up an avenue for the separation and extraction of oil droplets in the field of multiphase separation, biomedical analysis, microfluidics, etc.

Photothermal effect has attracted widespread attention in anti-icing surfaces due to energy saving and environmental friendliness. However, the development of surfaces with excellent photothermal performance is still limited in real engineering applications like aerospace by cheap material, facile fabrication and highly photothermal efficiency. Inspired by the optical features of the moth eye, a black engineering aluminum with high-efficiency solar anti-icing ability was developed through an ultrafast laser texturing treatment. The resultant anti-icing aluminum surface had regular micro/nano-scaled protrusions, showing good photothermal ability together with superhydrophobicity. The superhydrophobicity enables this surface to delay the freezing time by 5 times than blank one while the photothermal ability increases its surface temperature by 53 °C under one sun irradiation. The synergy of two abilities let the ice on its surface melt within 4 min. Additionally, the self-cleaning ability of the prepared surface enhances the anti-icing efficiency by removing absorbed contaminants affecting the photothermal effect adversely. This all-in-one integration of superhydrophobicity and photothermal effect finally boosts improved anti-icing performance as compared to the traditional superhydrophobic surface or individual photothermal materials. The work provides new insights into the design of enhanced anti-icing surface on the engineering materials with an advanced laser microfabrication.

Surface-enhanced Raman scattering (SERS) with unique molecular vibrational fingerprints for identifying analytes provides an effective spectroscopic approach for the detection of trace molecules in biomedical/analytical fields. Although a great amount of efforts has been devoted to developing various SERS substrates with hierarchical micro/nanostructures, challenges remain in completely concentrating the target molecules within a sensitive area and thereby enhancing detection sensitivity. Here, we report trace molecular detection using superhydrophobic microcrater array as surface-enhanced Raman substrate (SMA-SERS). The hierarchically ordered microcrater array with plasmonic nanoparticle clusters is quickly obtained by the two-step process of femtosecond laser texturing and magnetron sputtering. The resultant substrates with hierarchical micro-/nanostructures show excellent superhydrophobicity with a contact angle above 150° and satisfactory plasmonic nanostructures with the easily attainable Raman signal enhancement factor of ~4.82 × 108. The signals on the SMA-SERS maintain uniformity with a relative standard deviation of

Highly-performance fogdrop collection is of great practical importance in addressing the worldwide water shortages, especially in arid regions. Although great progresses have been made to solve this problem, there still are challenges in developing high-performance fogdrop collecting systems to satisfy efficient fogdrop capturing and fast transport simultaneously, which are two critical factors that determine the collection efficiency. The well-evolved water-collecting capacity of creatures that adapt to the harsh environment provides a great inspiration for the design of efficient collection systems. Here, inspired by the unique hierarchical structures and the excellent fogdrop collection ability of wheat awn, artificial awn-like hierarchical systems are developed via a precision 3D printing strategy which exhibit excellent fogdrop capture and fast transport. The presence of hierarchical structure composed of conical spine, gradient microgrooves, and oriented thorns enables the fogdrop collection to transform from dropwise mode on the thorns to filmwise one on the spine. Furthermore, the collection efficiency of such a bioinspired system is 5.90 g/cm−2·h, which is higher than individual ones and other bioinspired systems. Through the model of structure–function relationship, the mechanisms of diverse collecting behaviors are explored to address the origin of highly-performance collection. This work opens up new avenues to design systems and devices for dramatic fogdrop collection enhancement.