Related Articles
Optical sorting: past, present and future
Optical sorting combines optical tweezers with diverse techniques, including optical spectrum, artificial intelligence (AI) and immunoassay, to endow unprecedented capabilities in particle sorting. In comparison to other methods such as microfluidics, acoustics and electrophoresis, optical sorting offers appreciable advantages in nanoscale precision, high resolution, non-invasiveness, and is becoming increasingly indispensable in fields of biophysics, chemistry, and materials science. This review aims to offer a comprehensive overview of the history, development, and perspectives of various optical sorting techniques, categorised as passive and active sorting methods. To begin, we elucidate the fundamental physics and attributes of both conventional and exotic optical forces. We then explore sorting capabilities of active optical sorting, which fuses optical tweezers with a diversity of techniques, including Raman spectroscopy and machine learning. Afterwards, we reveal the essential roles played by deterministic light fields, configured with lens systems or metasurfaces, in the passive sorting of particles based on their varying sizes and shapes, sorting resolutions and speeds. We conclude with our vision of the most promising and futuristic directions, including AI-facilitated ultrafast and bio-morphology-selective sorting. It can be envisioned that optical sorting will inevitably become a revolutionary tool in scientific research and practical biomedical applications.
Sustainable solutions for water scarcity: a review of electrostatic fog harvesting technology
Amid global climate change and population growth, traditional water acquisition methods face challenges. Electrostatic fog harvesting technology offers a novel solution for arid regions, leveraging space charges and electric fields to convert fog into usable water. This article explores the fundamental processes, structure, and enhancement methods of electrostatic fog collectors (EFC), focusing on recent research progress. We offer a prospective perspective on the future research of electrostatic fog harvesting technology, with the aim of facilitating the transition of this technology from scientific research to practical application.
The growth of super-large pre-planetary pebbles to an impact erosion limit
The early evolution of dust in protoplanetary disks is dominated by sticking collisions. However, this initial phase of particle growth faces constraints, notably from destructive encounters. To find the maximum particle size achievable, we studied collisional processes during a prolonged microgravity experiment aboard a suborbital flight. Specifically, we describe an impact erosion limit. We observed individual basalt beads, each measuring 0.5 mm in diameter, colliding with and either eroding or adhering to a cluster several centimetres in size. This cluster, formed from tribocharged particles, simulates an electrostatic growth phase that surpasses the classical bouncing barrier. We found a threshold velocity of about 0.5 m s−1, which separates additive and erosive impacts of individual beads. Numerical simulations of grains impacting clusters, for both low and high charge constituents, corroborate the experimental findings of surface erosion within the observed velocity range. This specific velocity threshold supports the potential formation of pebbles several centimetres in size within protoplanetary disks. Such dimensions place these pebbles well into a regime in which hydrodynamic interactions might facilitate the formation of planetesimals.
Crossover scaling of structural and mechanical properties in 3D assemblies of non-spherical, frictional particles
The stability of particle assemblies is strongly affected by particle shape, yet definitive laws describing key properties, such as the mean contact number and apparent friction coefficient, remain elusive. Using X-ray computed tomography and discrete element simulations, we study 70 assemblies of 3D frictional particles. Once properly rescaled, our data collapse onto master curves, revealing linear relationships linking particle shape to these properties for short-axis particles below certain crossover points. These data suggest that the scaling behavior for the mean contact number can be maintained at lower sphericity than the apparent friction coefficient, indicating different sensitivity of the system’s structural versus mechanical properties to particle shape. Through analyzing elongated particles beyond the crossover points, we find that while particle elongation increases the contact number, it has limited effects on improving mechanical stability. This insight, along with the law, paves the route towards optimizing granular packing via manipulating particle shape.
Mass and particle size distribution of household dust on children’s hands
Children are vulnerable to household dust exposure; however, to date, a handful of studies simultaneously report both the mass and particle size of household dust found on children’s hands after natural indoor play activities.
Responses