On-dose authentication (ODA) enhances security by incorporating customized molecular or micro-tags into each pill, preventing counterfeit products in genuine packages. ODA's security relies on tag non-replication and non-reverse engineering. Combining ODA with graphical Physical Unclonable Functions (PUF) promises maximum security. PUF uses intrinsic micro or nanoscale randomness as a unique ‘fingerprint’. However, current graphical PUFs have limitations like specific illumination requirements and the use of toxic materials, restricting their use in pharmaceuticals. In this study, we propose a novel approach called on-dose PUF. This method involves embedding microspheres randomly within micro biocompatible hydrogel particles. We showcase two distinct types of such on-dose PUFs. The first type utilizes randomly distributed superparamagnetic colloids (SPC) of identical diameters, while the second type utilizes vortexed sunflower oil drops of various diameters. The diameter and coordinates of the microspheres serve as input for generating cryptographic keys. A universal circle identification and binning program is used for extracting this information. One advantage of this approach is that it enables imaging using white light illumination and low-magnification microscopy, as color and signal intensity information are not crucial. This method enables patients to verify their medication by using their mobile phones from home. To assess the performance of the proposed on-dose PUF, we conducted canonical investigations on the single-diameter system. This system can only generate one layer of cryptographic keys, making it potentially more vulnerable than the multiple-diameter system. However, the single-diameter system successfully passed NIST Statistical tests and exhibited sufficient randomness, ideal bit uniformity, Hamming distance, and device uniqueness. Furthermore, we found that the encoding capacity of the single-diameter system was 9.2×10¹⁸, providing ample labeling potential.

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Metal-organic frameworks (MOF) are a class of crystalline, porous materials possessing well-defined channels that have widespread applications across the sustainable landscape. Analogous to zeolites, these materials are well-suited for adsorption processes targeting environmental contaminants. Herein, a zirconium MOF, UiO-66, was functionalized with ferrocene for the selective removal of oxyanion contaminants, specifically NO₃^-, SO₄^2-, and PO₄^3-. Electrochemical oxidation of the embedded ferrocene pendants induces preferential adsorption of these oxyanions, even in the presence of Cl^- in a 10-fold excess. Anion selectivity strongly favoring PO₄^3- (S_oxy/comp = 3.80) was observed following an adsorption trend of PO₄^3- > SO₄^2- > NO₃^- > (10-fold)Cl^- in multi-ion solution mixtures. The underlying mechanisms responsible for ion selectivity were elucidated by performing ex situ X-ray photoelectron spectroscopy (XPS) on the heterogeneous electrode surface postadsorption and by calculating the electronic structure of various adsorption configurations. It was eventually shown that oxyanion selectivity stemmed from strong ion association with a positively charged pore interior due to the spatial distribution of charge by oxygen constituents. While ferrocenium provided the impetus for ion migration-diffusion, it was the formation of stable complexes with zirconium nodes that ultimately contributed to selective adsorption of oxyanions.

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Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied—a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteristic scales for velocity, time and energy to depend solely on the channel geometry. Contrary to the generally assumed absence of instability in low Reynolds number flows (<1000), we report a momentary flow distortion that originates due to the boundary layer separation near channel walls during flow deceleration. The emergence of distorted laminar states is characterized using two stages. First the conditions for the onset of instabilities is analyzed using the Reynolds number and Womersley number for oscillating flows. Second the growth and the ability of an instability to prevail is analyzed using the convective time scale of the flow. Our findings inform rational design of microsystems leveraging pulsatile flows via cavitation-powered microactuation.

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Boron contamination of various water sources has been increasing in recent years and is receiving worldwide attention for its negative effects on the environment, wildlife, and humans; therefore, its removal is of utmost importance. Considering dwindling water sources and the possibility of the world population soon experiencing water scarcity, effective and innovative technologies must be developed to remove boron ions from water sources. The aim of the present study was to assess a sustainable separation process for the removal of boron ions using an electrochemical flow cell with symmetric redox-active polyvinyl ferrocene (PVF) functionalized carbon nanotube (CNT) electrodes using real-time measurements of the boron adsorption performance in continuous-flow mode while varying the flow rate, cell voltage, and boron concentration. A Box–Behnken experimental design (BBD) was used to improve boron adsorption. The adsorption isotherms, kinetics, and thermodynamics were investigated to further describe the adsorption process. The high R² value, calculated using a linear and nonlinear procedure, demonstrated that the Langmuir isotherm and pseudo-first order models fit quite well. The maximum adsorption of 60.61 mg/g was observed. The thermodynamic results illustrated that the adsorption of boron ions onto the PVF/CNT electrodes was spontaneous and endothermic under continuous flow mode.

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Correction to: Scientific Reportshttps://doi.org/10.1038/s41598-024-68971-x, published online 13 August 2024 In the original version of this Article a previous rendition of Figure 2B, Figure 4 and Figure 5D was published. The original Figure 2, 4 and 5 and accompanying legends appear below. (Figure presented.) (Figure presented.) (Figure presented.) (A) Representative bubble dynamics for different channel geometries. (B) Universal motion of bubbles within channels with different size, shape and length. The dashed line represents the developed theory, Eq. (2). The marker colors represent the hydraulic diameters (d_h), the shapes represent the cross-section and the facecolor represent the lengths (L). The graphical marker symbols and colors established here are followed throughout this article. The black arrow represents the region of deviation(s) from the expected dynamics. The threshold laser energy absorbed for bubble formation estimated from experiments (E_th,exp) against theory (E_th,theory) presented in Eq. (5). (A,B) Representative dynamic bubble size curves illustrating the emergence of instabilities. The zones of the instabilities are highlighted using a shaded rectangular area. The arrows represent if the instabilities occur before or after X_max. (A) Illustrates the experimental data for different d_h with similar oscillation time. The instabilities emerge with increasing d_h. (B) Illustrates the data for d_h = 200 µm with increasing laser energies. The instabilities disappear with increasing E_abs. (C) Flow stability diagram with the transition line at W_o = 734. The markers represent the experiments and the lines represent the analytical estimate. The numbers correspond to the channel hydraulic diameters (in µm) with the dashed and solid lines representing the channel lengths L = 25 and 50 mm, respectively. (D) The dimensionless convective timescale against the L/d_h aspect ratio. The partition line is a linear relation between the x and y axes with 45 × 10⁻⁶ as the slope and the origin as the intercept. The original Article has been corrected.

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Crystallization abounds in nature and industrial practice. A plethora of indispensable products ranging from agrochemicals and pharmaceuticals to battery materials are produced in crystalline form in industrial practice. Yet, our control over the crystallization process across scales, from molecular to macroscopic, is far from complete. This bottleneck not only hinders our ability to engineer the properties of crystalline products essential for maintaining our quality of life but also hampers progress toward a sustainable circular economy in resource recovery. In recent years, approaches leveraging light fields have emerged as promising alternatives to manipulate crystallization. In this review article, we classify laser-induced crystallization approaches where light-material interactions are utilized to influence crystallization phenomena according to proposed underlying mechanisms and experimental setups. We discuss nonphotochemical laser-induced nucleation, high-intensity laser-induced nucleation, laser trapping-induced crystallization, and indirect methods in detail. Throughout the review, we highlight connections among these separately evolving subfields to encourage the interdisciplinary exchange of ideas.

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Electrochemical carbon dioxide (CO₂) reduction is a promising route to convert intermittent renewable energy into fuels and valuable chemical products. Separation of CO₂ reduction products by ion-selective electrochemical technology may play a decisive role in the pursuit of commercially viable CO₂ reduction processes. Selective separation of formate, one of the main CO₂ reduction products, is assessed in the present study in an electrochemical flow cell with symmetric redox-active polyvinyl ferrocene (PVF) functionalized graphene oxide (GO) electrodes. First, experimental parameters such as the PVF/GO ratio, sonication time, and ultrasonic amplitude, were optimized in the electrode preparation process to improve the formate adsorption efficiency on a lab scale (1 × 2 cm electrodes) under static conditions. The electrochemical and morphological characteristics of the electrodes were investigated by cyclic voltammetry and scanning electron microscopy. To demonstrate continuous-flow operation, an electrosorption flow cell (8 × 8 cm) providing inline measurements was constructed. The flow cell results showed selectivity at > 5.5 toward the removal of formate from an electrolyte containing perchlorate at an excess of 30 times the normal value. The performance of the electrosorption cell was also tested using a mixture of methanol, ethanol, formate, and acetaldehyde produced in a CO₂ reduction electrolyzer. In this demonstration, formate separation was achieved with a selectivity of > 4.0. The results suggest that the optimized design of the electrochemical cell and operation conditions of the flow platform pave the way for scaling up selective formate separation with PVF/GO electrodes.

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We experimentally and numerically study the dynamics of a liquid jet issued from a rotating orifice, whose breakup is regulated by a vibrating piezo element. The helical trajectory of the spiralling jet yields fictitious forces varying along the jet whose longitudinal projections stretch and thin the jet, affecting the growth of perturbations. We show that by quantifying these fictitious forces, one can estimate the jet intact length and size distribution of drops formed at jet breakup. The presence of the locally varying fictitious forces may render high-frequency perturbations, that would otherwise be stable in the abscence of stretching, unstable, as observed similarly in the case of straight jets stretching under gravity. The perturbation amplitude then dictates how strong the perturbation is coupled to the jet compared with random noise that is inherently present in any experimental set-up. In the present study we exploit the slenderness of the jet to separate the calculation of the base flow and the growth of perturbations. The fictitious forces calculated from the base flow trajectory are then used in a nonlinear slender-jet model, which treats the spiralling jet as a quasi-straight jet with locally varying body forces. We show both experimentally and numerically that jet breakup characteristics (e.g. intact length and drop size distribution) can be controlled by finite-amplitude perturbations created by mechanically induced pressure modulations. Finally, we revisit the integrated net gain approach developed for straight jets under gravity and we provide simple analogous relations for spiralling jets.@en

Selective ion separation is a fundamental challenge with applications ranging from the manufacturing of pharmaceuticals & industrial salts to water desalination. In particular, the separation of formate, a primary product of electrochemical carbon dioxide reduction, has attracted attention not only to reduce carbon emissions and energy costs but to provide new routes to value-added chemicals. In the present study, selective formate separation from an aqueous solution is demonstrated using an electrochemical flow cell with symmetric redox-active polyvinyl ferrocene electrodes. An electrosorption system equipped with an electrosorption cell, inline conductivity, and pH sensors was constructed to provide real-time measurements of the formate adsorption performance in continuous flow mode while varying operating conditions such as the flow rate, cell voltage, and electrolyte concentration. These parameters were optimized using a Box–Behnken experimental design to improve the formate adsorption selectivity. The flow cell results showed a selectivity higher than 6.0 toward the removal of formate in an electrolyte containing a 30-fold excess of perchlorate under optimal operation conditions (i.e., 0.5 mL/min flow rate, 1.0 V, and 15 mM electrolyte concentration). The performance of the flow cell was also tested using a solution that contained different liquid CO₂ reduction products, and formate separation was achieved. The results suggest that the proper design of the electrochemical cell and efficient operation of the flow platform pave the way for scaling up the technology for selective formate separation.

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Optofluidic devices have revolutionized the manipulation and transportation of fluid at smaller length scales ranging from micrometers to millimeters. We describe a dedicated optical setup for studying laser-induced cavitation inside a microchannel. In a typical experiment, we use a tightly focused laser beam to locally evaporate the solution laced with a dye resulting in the formation of a microbubble. The evolving bubble interface is tracked using high-speed microscopy and digital image analysis. Furthermore, we extend this system to analyze fluid flow through fluorescence-Particle Image Velocimetry (PIV) technique with minimal adaptations. In addition, we demonstrate the protocols for the in-house fabrication of a microchannel tailored to function as a sample holder in this optical setup. In essence, we present a complete guide for constructing a fluorescence microscope from scratch using standard optical components with flexibility in the design and at a lower cost compared to its commercial analogues.@en

Herein, we study the influences of the laser-exposed volume and the irradiation position on the nonphotochemical laser-induced nucleation (NPLIN) of supersaturated potassium chloride solutions in water. The effect of the exposed volume on the NPLIN probability was studied by exposing distinct milliliter-scale volumes of aqueous potassium chloride solutions stored in vials at two different supersaturations (1.034 and 1.050) and laser intensities (10 and 23 MW/cm²). Higher NPLIN probabilities were observed with increasing laser-exposed volume as well as with increasing supersaturation and laser intensity. The measured NPLIN probabilities at different exposed volumes are questioned in the context of the dielectric polarization mechanism and classical nucleation theory. No significant change in the NPLIN probability was observed when samples were irradiated at the bottom, top, or middle of the vial. However, a significant increase in the nucleation probability was observed upon irradiation through the solution meniscus. We discuss these results in terms of mechanisms proposed for NPLIN.

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The increasing prevalence of calcium pyrophosphate dihydrate (CPPD) deposition disease, a form of arthritis with high inflammatory potential, has triggered considerable interest in the search for additives to prevent CPPD crystal formation, particularly in the field of biomineralization. In this context, CPPD crystallization in aqueous solution with and without glycine, glutamic acid, or glycyl-L-glutamic acid as crystal-growth modifier was experimentally investigated. The produced crystals were characterized structurally, morphologically, and in terms of their surface charge. In addition, the thermal degradation profiles of CPPD crystals obtained with and without the modifiers were characterized by TGA-FTIR, and the major volatile product was H₂O.

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Large amounts of carbon monoxide are produced by industrial processes such as biomass gasification and steel manufacturing. The CO present in vent streams is often burnt, this produces a large amount of CO₂, e.g., oxidation of CO from metallurgic flue gasses is solely responsible for 2.7% of manmade CO₂ emissions. The separation of N₂ from CO due to their very similar physical properties is very challenging, meaning that numerous energy-intensive steps are required for CO separation, making the CO separation from many process streams uneconomical in spite of CO being a valuable building block in the production of major chemicals through C1 chemistry and the production of linear hydrocarbons by the Fischer-Tropsch process. The development of suitable processes for the separation of carbon monoxide has both industrial and environmental significance. Especially since CO is a main product of electrocatalytic CO₂ reduction, an emerging sustainable technology to enable carbon neutrality. This technology also requires an energy-efficient separation process. Therefore, there is a great need to develop energy efficient CO separation processes adequate for these different process streams. As such the urgency of separating carbon monoxide is gaining greater recognition, with research in the field becoming more and more crucial. This review details the principles on which CO separation is based and provides an overview of currently commercialised CO separation processes and their limitations. Adsorption is identified as a technology with the potential for CO separation with high selectivity and energy efficiency. We review the research efforts, mainly seen in the last decades, in developing new materials for CO separation via ad/bsorption and membrane technology. We have geared our review to both traditional CO sources and emerging CO sources, including CO production from CO₂ conversion. To that end, a variety of emerging processes as potential CO₂-to-CO technologies are discussed and, specifically, the need for CO capture after electrochemical CO₂ reduction is highlighted, which is still underexposed in the available literature. Altogether, we aim to highlight the knowledge gaps that could guide future research to improve CO separation performance for industrial implementation.

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Elevated humidity levels in medical, food, and pharmaceutical products may reduce the products' shelf life, trigger bacterial growth, and even lead to complete spoilage. In this study, we report a humidity indicator that mechanically bends and rolls itself irreversibly upon exposure to high humidity conditions. The indicator is made of two food-grade polymer films with distinct ratios of a milk protein, casein, and a plasticizer, glycerol, that are physically attached to each other. Based on the thermogravimetric analysis and microstructural characterization, we hypothesize that the bending mechanism is a result of hygroscopic swelling and consequent counter diffusion of water and glycerol. Guided by this mechanism, we demonstrate that the rolling behavior, including response time and final curvature, can be tuned by the geometric dimensions of the indicator. As the proposed indicator is made of food-grade ingredients, it can be placed directly in contact with perishable products to report exposure to undesirable humidity inside the package, without the risk of contaminating the product or causing oral toxicity in case of accidental digestion, features that commercial inedible electronic and chemo-chromatic sensors cannot provide presently.

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Non-photochemical laser-induced nucleation (NPLIN) has emerged as a promising primary nucleation control technique offering spatiotemporal control over crystallization with potential for polymorph control. So far, NPLIN was mostly investigated in milliliter vials, through laborious manual counting of the crystallized vials by visual inspection. Microfluidics represents an alternative to acquiring automated and statistically reliable data. Thus we designed a droplet-based microfluidic platform capable of identifying the droplets with crystals emerging upon Nd:YAG laser irradiation using the deep learning method. In our experiments, we used supersaturated solutions of KCl in water, and the effect of laser intensity, wavelength (1064, 532, and 355 nm), solution supersaturation (S), solution filtration, and intentional doping with nanoparticles on the nucleation probability is quantified and compared to control cooling crystallization experiments. Ability of dielectric polarization and the nanoparticle heating mechanisms proposed for NPLIN to explain the acquired results is tested. Solutions with lower supersaturation (S = 1.05) exhibit significantly higher NPLIN probabilities than those in the control experiments for all laser wavelengths above a threshold intensity (50 MW/cm²). At higher supersaturation studied (S = 1.10), irradiation was already effective at lower laser intensities (10 MW/cm²). No significant wavelength effect was observed besides irradiation with 355 nm light at higher laser intensities (≥50 MW/cm²). Solution filtration and intentional doping experiments showed that nanoimpurities might play a significant role in explaining NPLIN phenomena.

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We demonstrate that a cavitation bubble initiated by a Nd:YAG laser pulse below breakdown threshold induces crystallization from supersaturated aqueous solutions with supersaturation and laser-energy-dependent nucleation kinetics. Combining high-speed video microscopy and simulations, we argue that a competition between the dissipation of absorbed laser energy as latent and sensible heat dictates the solvent evaporation rate and creates a momentary supersaturation peak at the vapor-liquid interface. The number and morphology of crystals correlate to the characteristics of the simulated supersaturation peak.

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We present a droplet microfluidic platform mixing the contents of the droplet chaotically in microfluidic induction time measurements, a promising method for quantifying nucleation kinetics with minute amounts of solute. The nucleation kinetics of aqueous potassium chloride droplets dispersed in mineral oil without surfactants is quantified in the presence and absence of chaotic mixing. We demonstrate the ability of the proposed platform to dictate droplet size, to provide a homogeneous temperature distribution, and to chaotically mix the droplet contents. Chaotic mixing in induction time measurements is facilitated by the motion of droplets through serpentine micromixer bends, while the extent of mixing is controlled by how much droplets move. Different nucleation kinetics are observed in experiments where the droplets are static, mixed, and in motion. We hypothesize that the droplet motion induces formation of a thin-liquid Bretherton film surrounding the droplets. The thin film shields droplets from solid boundaries that are more efficient heteronucleant surfaces compared to liquid-liquid interfaces. We observed that repeated microfluidic induction time measurements, particularly with moving droplets, produce significantly distinct cumulative nucleation probability curves, indicating that the measured nucleation kinetics depend strongly on the details of the experimental procedure, which we discuss in detail. Finally, we compare the microfluidic experiments to well-mixed, milliliter volume, turbidity-based measurements in the context of classic nucleation theory.

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The selective separation of ions is a major technological challenge having far-ranging impacts from product separation in electrochemical production of base chemicals from CO₂ to water purification. In recent years, ion-selective electrochemical systems leveraging redox-materials emerged as an attractive platform based on their reversibility and remarkable ion selectivity. In the present study, we present an ultrasound-intensified fabrication process for polyvinyl ferrocene (PVF)–functionalized electrodes in a carbon nanotube (CNT) matrix for selective electro-adsorption of formate ions. To this end, a response surface methodology involving the Box–Behnken design with three effective independent variables, namely, PVF to CNT ratio, sonication duration, and ultrasonic amplitude was applied to reach the maximum formate adsorption efficiency. The fabricated electrodes were characterized using cyclic voltammetry, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). SEM images revealed that an optimized ultrasonic amplitude and sonication time provided remarkable improvements in electrode morphology. Through a sedimentation study, we qualitatively demonstrate that the main optimized conditions improved PVF/CNT dispersion stability, consequently providing the highest number of active surface sites for adsorption and the highest adsorption efficiency. The highest percentage of active electrode surface sites and the maximum adsorption efficiency were 97.8 and 90.7% respectively at a PVF/CNT ratio of 3, ultrasonication time of one hour, and 50% ultrasonic amplitude.

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A microfluidic platform for continuous synthesis of hydrogel microparticles with superparamagnetic colloids (SPCs) embedded at prescribed positions is described. The shape of the cross-linked microparticle is independently controlled by stop–flow lithography, whereas the position of trapped SPCs are dictated by virtual magnetic moulds made of 2D nickel patches facilitating magnetic trapping. The spatial positions of trapped SPCs collectively function as a binary code matrix for product authentication. Analytical and finite element methods are combined to optimize the trapping efficiency of SPCs by systematically investigating magnetic field microgradients produced by nickel patches. It is envisioned that the proposed magnetic microparticles will contribute to the development of soft matter inspired product quality control, tracking and anti-counterfeiting technologies.

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The struvite crystals constitute one of the common types of urinary stones. Such stones are also referred as “infection stones” due to their tendency to cause infections in urinary tract. A considerable effort has been placed to identify natural or synthetic crystal-growth modifiers for this kind of urinary stone in literature, yet macromolecules commonly found in urine have been underexplored. In the present study, we experimentally focus on how hyaluronic acid, a protein commonly found in urine, alters the struvite crystallization in aqueous solution and in an artificial urine media. By gradually adding ammonium dihydrogen phosphate to a solution containing magnesium chloride hexahydrate, reactive crystallization is carried out in a well-mixed and thermostated vessel at 37 °C. The resulting struvite crystals are characterized structurally by XRD and FTIR as well as morphologically and in terms of their surface charge. In addition, the thermal decomposition behavior of the struvite with and without hyaluronic acid and released volatile products were simultaneously investigated using a TGA/FTIR system. The average activation energy calculated using the Friedman method was 49.2 ± 5.1 kJ/mol. The results of the kinetic and thermodynamic analyses showed that decomposition of the struvite crystals was endothermic and followed the multiple stage reaction mechanism.

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