Investigating the Nucleation Kinetics of Calcium Carbonate Using a Zero-Water-Loss Microfluidic Chip

Abstract

Characterization of nucleation processes is essential to the development of strategies to control crystallization in many industrial, atmospheric, biological, and geological environments. An effective route to studying nucleation processes is the use of large numbers of small, identical volumes, where these minimize the effects of impurities that can dominate in bulk solution and allow the stochastic nature of nucleation to be considered. Here, we present a multilayered microfluidic device for nucleation studies that can be used to carry out 10 000 simultaneous reactions in identical microcavities, and 500 of them are used for investigating nucleation kinetics. Unlike droplet-based systems, no surfactants are required, and the presence of an integrated water

Ultrasensitive detection of mercury(ii) in aqueous solutions via the spontaneous precipitation of CsPbBr3 crystallites

“…Mercury was found to incorporate into the crystal lattice and caused quenching of the fluorescence when Hg 2+ was present in the sample solution with the CsPbBr 3 precursor. Microwells were used to speed up the precipitation process and the elimination of random products caused by crystallization stochastics, 21 and Hg 2+ was enriched by water evaporation. The lowest detection limit for this strategy was as low as 0.1 nM, which is applicable for the high standards of drinking water.…”

Static and Surfactant-Free Quasi-Double Emulsions as Programmable Microcrystallizers for Controllable Polymorphic Crystallization

“…In the double emulsions, the middle oil shell could function as a selective barrier to regulate molecule transport, allowing diffusion of small chemicals or molecules between the outer phase and the inner phase, thus providing more controls of the aqueous environment, such as concentration, composition, and pH. − Despite these distinctive advantages, the double-emulsion platform is not easily adopted for polymorphic selection in routine academic or industrial practice due to the demands of sophisticated device fabrication and delicate fluid control. − Additionally, the conventional double emulsions are in vesicular droplet format and thermodynamically unstable systems and prone to coalescence and destabilization during storage or incubation, − which limits their application in long-term experiments, including crystallization. Worse yet, the vesicle-type double emulsions require the addition of surfactants for stabilizing double-emulsion droplets, which may lead to unwanted heterogeneous nucleation. , …”

“…Worse yet, the vesicle-type double emulsions require the addition of surfactants for stabilizing double-emulsion droplets, which may lead to unwanted heterogeneous nucleation. 26,27 In this paper, we develop a novel double-emulsion platform for facilely and flexibly controlling crystal polymorphism. This platform utilizes a thin layer of oil to separate an array of aqueous droplets trapped in microwells from a continuous aqueous phase, forming a large number of water−oil−water (W/O/W) structures similar to double emulsions (as shown in Figure 1a), which we call "quasi-double emulsion" (QDE).…”

Screening the Ion Compositions on Crystal Morphology Transitions by a Microfluidic Chip with a Well-Defined Concentration Gradient

“…36 Zhang et al developed a microfluidic chip with large numbers of microwells to study the nucleation process of calcium carbonate. 37 Recent developments of on-chip analysis techniques using a synchrotron light source have expanded the capabilities of exploring the underlying dynamic process of crystallization such as nucleation 38 and transformations 39 in a confined space. Therefore, the microfluidic technique including the design of novel microstructures and on-chip characterization methods is an ideal platform to study crystallization with more precise control over the crystallization conditions.…”

“…Gong et al used a “crystal hotel” microfluidic chip to study the growth of crystals in a confined space, and Kim et al used a similar chip to study the additive effect on the morphology at an early stage and found that soluble additives have no influence on calcite crystals at an early stage . Zhang et al developed a microfluidic chip with large numbers of microwells to study the nucleation process of calcium carbonate . Recent developments of on-chip analysis techniques using a synchrotron light source have expanded the capabilities of exploring the underlying dynamic process of crystallization such as nucleation and transformations in a confined space.…”