Fluid Flow Control Research Articles

When Liquid Droplets Take a Turn

A new model reveals that patterns of internal fluid flow control whether self-propelling water droplets in oil follow linear or curved trajectories.

Numerical duality of MHD stagnation point flow and heat transfer of nanofluid past a shrinking/stretching sheet: Metaheuristic approach

In the present era of Industry 4.0, automation, and nanotechnology, many industrial applications require the simultaneous control of heat and fluid flow for better efficiency of machines. The polymeric excursion process, manufacturing of plastic films, glass, metallic equipment, all need control over friction forces and heat flow rates. Considering the importance of the subject, the present study deals with the stagnation point flow and heat transfer of water-based nanofluid over a stretching/shrinking sheet with a non-aligned axis of symmetry. The permeable sheet is considered in the presence of a uniform magnetic field. The non-linear partial differential equations governing the flow and heat transfer are converted into non-linear coupled ordinary differential equations using similarity transformations. The resultant equations are solved using “Particle Swarm Optimization” and Runge-Kutta method based hybrid shooting technique. Considering the nanoparticle size, concentration and shape-dependence on physical and thermal properties of nanofluid more realistic aggregation based mathematical models are used for both viscosity and thermal conductivity. Numerical results for the velocity profile, non-alignment function, temperature distribution and local skin friction are discussed with respect to the physical parameters like nanoparticle concentration, nanoparticle size, magnetic field, suction, and stretching/shrinking velocity. The existence of dual solutions are observed for the shrinking velocity parameter λ<−1, and the practically realizable and stable solutions are filtered out by computing the eigenvalues for the formulated perturbed Eigen problem. The results for the stable solutions unveiled that, by changing the stretching velocity parameter λ from 0 to 0.5, there is approximately 38% enhancement in heat transfer rate and 42% decrement in skin friction coefficient. Moreover, in the case of shrinking velocity parameter λ=−1.25, with an increase in nanoparticle concentration from 0 to 5%, the skin friction coefficient reduces by 53%, whereas the change in nanoparticle size from 10 nm to 50 nm has a skin friction reduction of only 10%.

Anisotropic wetting surfaces machined by diamond tool with tips microstructured by focused ion beam

In recent years, there has been an increasing interest in methods to fabricate hydrophobic surfaces. Hydrophobic surfaces have been used in multiple applications in microfluidic devices to control fluid flow, as self-cleaning surfaces and also in de-icing or for drag reduction. Conventionally, hydrophobic surfaces were created by laser processing, self-assembly and other chemical processing methods. However, in many of these methods, hydrophobicity of the surface cannot be maintained for an extended time or restricted to limited set of materials. In some applications, creation of anisotropy in the hydrophobic property and the ability to pattern it, is important. Here, a low-cost, high-throughput method to generate highly hydrophobic and anisotropic surface has been developed. This method uses Computer Numerical Control machining employing diamond tools whose tips have been micro-structured using Focused Ion Beam that enables parallelization and achieves at least four times higher machining speed compared with other methods. The versatility of this method has been demonstrated by machining both metal and polymeric materials. Significant anisotropic wetting has been observed on the machined surface with the anisotropy in directional contact angle of up to 71.6°. Highly-hydrophobic surfaces with contact angle of 163.1° on 6061 Aluminum Alloy and 155.7° on polymethyl methacrylate surface were created.

Scaling up the throughput of microfluidic droplet-based materials synthesis: A review of recent progress and outlook.

The last two decades have witnessed tremendous progress in the development of microfluidic chips that generate micrometer- and nanometer-scale materials. These chips allow precise control over composition, structure, and particle uniformity not achievable using conventional methods. These microfluidic-generated materials have demonstrated enormous potential for applications in medicine, agriculture, food processing, acoustic, and optical meta-materials, and more. However, because the basis of these chips' performance is their precise control of fluid flows at the micrometer scale, their operation is limited to the inherently low throughputs dictated by the physics of multiphasic flows in micro-channels. This limitation on throughput results in material production rates that are too low for most practical applications. In recent years, however, significant progress has been made to tackle this challenge by designing microchip architectures that incorporate multiple microfluidic devices onto single chips. These devices can be operated in parallel to increase throughput while retaining the benefits of microfluidic particle generation. In this review, we will highlight recent work in this area and share our perspective on the key unsolved challenges and opportunities in this field.

Impacts of Uniform Magnetic Field and Internal Heated Vertical Plate on Ferrofluid Free Convection and Entropy Generation in a Square Chamber.

The heat transfer enhancement and fluid flow control in engineering systems can be achieved by addition of ferric oxide nanoparticles of small concentration under magnetic impact. To increase the technical system life cycle, the entropy generation minimization technique can be employed. The present research deals with numerical simulation of magnetohydrodynamic thermal convection and entropy production in a ferrofluid chamber under the impact of an internal vertical hot sheet. The formulated governing equations have been worked out by the in-house program based on the finite volume technique. Influence of the Hartmann number, Lorentz force tilted angle, nanoadditives concentration, dimensionless temperature difference, and non-uniform heating parameter on circulation structures, temperature patterns, and entropy production has been scrutinized. It has been revealed that a transition from the isothermal plate to the non-uniformly warmed sheet illustrates a rise of the average entropy generation rate, while the average Nusselt number can be decreased weakly. A diminution of the mean entropy production strength can be achieved by an optimal selection of the Lorentz force tilted angle.

Mechanowetting drives droplet and fluid transport on traveling surface waves generated by light-responsive liquid crystal polymers

In nature, capillary forces are often driving microfluidic propulsion and droplet manipulation, and technologies have been developed to utilize these forces in applications such as lab-on-a-chip biosensors and microfluidic systems. At the same time, responsive materials have been developed that can be activated by a variety of external triggers, including light, electric fields, and temperature, to locally deform and create dynamic surface structures, such as traveling waves. Here, we combine these developments into a system that enables capillary-driven droplet transport and fluid propulsion generated by light-induced surface waves in azobenzene-embedded liquid crystal polymers. We demonstrate that the traveling waves are able to efficiently propel fluids by means of mechanowetting. We couple the wave profiles to the fluid simulations using a multiphase computational fluid dynamics approach. We study three different fluid propulsion systems, i.e., peristaltic flow, liquid slug transport, and free-standing droplet transport. The first system operates on a fluid-filled single channel and achieves relative flow speeds of u/uwave&amp;lt;0.01. In contrast, the slugs and droplets are transported at two orders of magnitude higher speed equal to the wave speed (u/uwave=1) by exploiting the mechanowetting effect. We quantify the capillary forces generated by the traveling surface waves. Our method opens new avenues in light-driven (digital) microfluidic systems with enhanced control of fluid flow.

Design of Microwave Antenna Array for Imaging of Multiphase Flows in Polypropylene Pipes

The oil and gas industry requires accurate sensors to control fluid flow in pipelines during the production process from horizontal and near horizontal wells. The extracted crude oil is usually a multiphase mixture of oil, water, and gas, and the accurate measurement of the ratio of each multiphase within the pipeline is an important parameter to manage wells efficiently by maximizing the hydrocarbons that can be extracted. Various methods have been developed for determining the phase ratio including mechanical, optical, X-ray or gamma ray, ultrasound, nuclear magnetic resonance (NMR), and rarely microwave techniques. However, these methods do not permit the knowledge of the real-time evolution of the phase ratio and are less precise. Here, we propose and develop by simulation two microwave systems, in horizontal and vertical polarizations, to choose the optimal configuration for crude pipeline imaging applications. First, the pipeline containing crude oil was modeled and its thermal and dielectric properties are proposed. Then, the antennas array performances were optimized and assembled to the pipeline. Different numbers of antenna elements were successfully investigated using CST simulation in both vertical and horizontal polarizations to find the optimal number of antenna elements for the pipeline applications.

3D Printing of Monolithic Capillarity-Driven Microfluidic Devices for Diagnostics.

Rapid diagnostic testing at the site of the patient is essential when a fully equipped laboratory is not accessible. To maximize the impact of this approach, low-cost, disposable tests that require minimal user-interference and external equipment are desired. Fluid transport by capillary wicking removes the need for bulky ancillary equipment to actuate and control fluid flow. Nevertheless, current microfluidic paper-based analytical devices based on this principle struggle with the implementation of multistep diagnostic protocols because of fabrication-related issues. Here, 3D-printed microfluidic devices are demonstrated in a proof-of-concept enzyme-linked immunosorbent assay in which a multistep assay timeline is completed by precisely engineering capillary wetting within printed porous bodies. 3D printing provides a scalable route to low-cost microfluidic devices and obviates the assembly of discrete components. The resulting rapid and seamless transition between digital data and physical objects allows for rapid design iterations, and opens up perspectives on distributed manufacturing.

Hydraulic Fracturing Tight Reservoirs: Rock Mechanics and Transport Phenomena

Conventional reservoirs have been fracture stimulated using acid fracturing and proppant fracturing.Acid fracturing is performed to improve well productivity in acid-soluble formations such aslimestone, dolomite, and chalk. Hydrochloric acid is generally used to create an etched fracture,which is the main mechanism for maintaining the fracture open during the life of a well. Proppantfracturing is an alternative option that has been applied in carbonaceous and siliceous formations.There is no quantitative method to provide an answer of whether acid fracturing or proppantfracturing is an appropriate stimulation method for a given carbonate formation. How rockmechanics can be applied to decide on what method is more effective? Laboratory experiments havebeen performed to simulate acid etched to study the effect of elastic, plastic and viscoelastic rockbehavior and their effects on fracture conductivity. Comparison of acid vs. proppant fracturingconductivity in carbonate formation is presented.Fracturing low permeability reservoirs is totally different than fracturing tight formations. Thefracture geometry required in low permeability reservoirs need to be planar, conductive andpenetrating deep in the reservoir. Fracture complexity in these reservoirs is to be avoided foroptimum stimulation treatment. However, in fracturing tight formation, a complex fracture networkis desirable for better recovery. Creating multiple fractures in horizontal wells without the use ofmechanical intervention, is becoming essential especially in tight gas reservoirs. We have learnedhow to initiate hydraulic fractures into a specific direction and place as many fractures as desired inhorizontal wells but with casing and perforation. The challenge now is to initiate weak point acrossthe horizontal well such that fracturing fluid will initiate a fracture there. How rock mechanics hasbeen applied to achieve this objective? We are fracturing tight gas sand in harsh environment, atdepth more than 18000 ft, of temperature close to 400 °F, and one can figure out the extreme in-situstresses relevant to this depth.When the reservoir pressure decreases, the elastic displacement in response to the increase ineffective stress will cause natural fractures to close leading to a decline in reservoir productivity.&#x0D; The matrix medium feeds the natural tensile fractures which carry the fluids to the wellbore. Thedecline in conductivity with increasing effective stress should follow a logical declining rate tosupport a given production rate. How the concept of effective stress has been applied to understandthe stress-dependent conductivity of various conductive components of a given reservoir? Rockmechanics testing of these stress sensitive reservoirs becomes vital to optimize fracturing tightformations.Economical production from tight reservoirs, including shale gas and shale oil formations, requireshorizontal well drilling and massive proppant hydraulic fracturing stimulation. The stimulationinvolves generating sufficient fractures network or stimulated reservoir volume (SRV), which isachieved by placing optimized stimulation treatments along the horizontal section of wellboresideally drilled from multi-well pads to increase the production rate and ultimate recovery. Hydraulicfracturing in naturally fractured formations is characterized by generating a fractures’ network thatshould be designed for in extremely low permeability of unconventional reservoirs. Fractures shouldextensively reach shale matrix to achieve commercial gas production. Therefore, production rate andultimate recovery depend on the size of the created SRV.The transport phenomena controlling fluid flow through tight formation is no longer sufficient to bemodeled by Darcy’s flow. Diffusion and imbibition are important transport mechanisms. The conceptof osmosis and flow through a semi-permeable membrane component are critical. Additionally,diffusion and a special case of molecular flow due to Knudson effect will be discussed. Conventionalreservoir simulation collapses when trying to simulate fluid flow through tight reservoirs. Numericalstudies on a hydraulically fractured well to simulate the dynamic processes during fracturinginjection, following well shut-in (soaking), and production are discussed.

Go with the capillary flow. Simple thread-based microfluidics

• Review of capillary flow enabled thread-based microfluidics development. • Review of threads’ capillarity and fluid flow control strategies. • Mainstream detection methods applied on thread-based microfluidics. • Applications on blood separation and analysis, immunoassays, and wearable sensing. • Trend in smartphone-compatible thread microfluidics for onsite applications. Studies on microfluidic thread-based analytical devices (μTADs) have been developed for a decade. Threads, made of natural cellulose or synthesized polymer fibres, are manufactured in the form which possesses a large number of capillary gaps for liquid transport, and show differences in structural morphologies and surface chemistry. Threads have been used to design simple thread-based microfluidics with different analytical functions. Due to their low-cost, portability, biocompatibility and ease of integration with other components, threads show a great application basis to fabricate point-of-care μTADs. To date, there are a limited number of published studies on μTADs in contrast to paper-based analytical devices. To facilitate further advances of μTADs, this review summarizes the development of these devices from the aspects of engineering control of capillary flow on threads and biological applications. Particularly, as liquid flow on threads affects the transport and detection efficiencies, strategies of controlling liquid flow on threads are firstly reviewed. This includes thread surface modification, proper thread type selection, and microfluidic channel design. Then various detection methods including colorimetry, fluorescence, electrochemistry and surface-enhanced Raman spectroscopy applied on μTADs are reviewed. The biological applications of μTADs in blood separation and analysis, immunoassay, wearable sensing, as well as compatibility with smartphones for biosensing are also systematically summarized. Finally, the future perspectives of μTADs regarding external collaboration to satisfy the “REASSURED” criteria are proposed. This review is expected to expand understandings of μTAD designs and applications, and to clarify the challenges and future development directions of μTADs.

Modeling Immunity In Vitro: Slices, Chips, and Engineered Tissues.

Modeling immunity in vitro has the potential to be a powerful tool for investigating fundamental biological questions, informing therapeutics and vaccines, and providing new insight into disease progression. There are two major elements to immunity that are necessary to model: primary immune tissues and peripheral tissues with immune components. Here, we systematically review progress made along three strategies to modeling immunity: ex vivo cultures, which preserve native tissue structure; microfluidic devices, which constitute a versatile approach to providing physiologically relevant fluid flow and environmental control; and engineered tissues, which provide precise control of the 3D microenvironment and biophysical cues. While many models focus on disease modeling, more primary immune tissue models are necessary to advance the field. Moving forward, we anticipate that the expansion of patient-specific models may inform why immunity varies from patient to patient and allow for the rapid comprehension and treatment of emerging diseases, such as coronavirus disease 2019.

3-D Geologic Controls of Hydrothermal Fluid Flow at Brady geothermal field, Nevada, USA

In many hydrothermal systems, fracture permeability along faults provides pathways for groundwater to transport heat from depth. Faulting generates a range of deformation styles that cross-cut heterogeneous geology, resulting in complex patterns of permeability, porosity, and hydraulic conductivity. Vertical connectivity (a throughgoing network of permeable areas that allows advection of heat from depth to the shallow subsurface) is rare and is confined to relatively small volumes that have highly variable spatial distribution. This local compartmentalization of connectivity represents a significant challenge to understanding hydrothermal circulation and for exploring, developing, and managing hydrothermal resources. Here, we present an evaluation of the geologic characteristics that control this compartmentalization in hydrothermal systems through 3-D analysis of the Brady geothermal field in western Nevada. A published 3-D geologic map of the Brady area is used as a basis to develop structural and geological variables that are hypothesized to control or effect permeability or connectivity. The 3-D distribution of these variables is compared to the distribution of productive and non-productive fluid flow intervals along production wells and non-productive wells via principal component analysis (PCA). This comparison elucidates which geologic and structural variables are most closely associated with productive fluid flow intervals. Results indicate that production intervals at Brady are located: (1) within or near to known and stress-loaded macro-scale faults, and (2) in areas of high fault and fracture density.

Enhancing vibration performance of a spinning smart nanocomposite reinforced microstructure conveying fluid flow

In this article, critical angular velocity, critical velocity of fluid flow and vibration control analysis of a rotating multi-hybrid nanocomposite reinforced (MHCR) cylindrical microshell covered with a piezoelectric layer as sensor and actuator (PLSA) are presented. The current non-classical model is capable of capturing the size dependency in the microshells using only one material length scale parameter; moreover, the mathematical formulation of microshells based on the classical model can be recovered from the present model by neglecting the material length scale parameter. This structure is under conveying viscous fluid, and the related force is calculated by the modified formulation of Navier–Stokes. In addition, the current structure rotates around its axial direction. The Coriolis and centrifugal effects due to the rotation are considered. For semi-numerical method, the strains and stresses can be determined through via the first-order shear deformable theory (FSDT). For accessing to various mass densities, thermal expansion as well as Poisson ratio, the rule of mixture is applied, although a modified Halpin–Tsai theory is used for obtaining the module of elasticity. The external voltage is applied to the sensor layer, while a Proportional-Derivative (PD) controller has been utilized for controlling output of sensors. The boundary conditions are derived through governing equations of the MHCR cylindrical microshell using energy method known as Hamilton’s principle and finally are solved using generalized differential quadrature method (GDQM). The outcomes show that the angular velocity, velocity of fluid flow, external force, PD controller, external voltage and MHC’s weight fraction have a considerable impact on the amplitude, and vibration behavior of a spinning MHCR cylindrical shell conveying fluid flow.

Hydrogeologic Property Estimation in Plate Boundary Observatory Boreholes Using Tidal Response Analysis

Because of the influence pore pressures have on effective stress, understanding hydrogeologic properties that control fluid flow and pressure distribution is important in characterizing earthquake and deformation processes. Here, we utilize borehole pressure changes in response to earth tides to determine hydrogeologic properties and their time variations for 17 boreholes within the NSF Earthscope’s Plate Boundary Observatory (PBO) network along the San Andreas fault and Cascadia subduction zone. Our analysis considers solutions for both confined and unconfined aquiares. Resulting permeability and hydraulic diffusivity values range from6.4×10−16–8.4×10−14 m2 and1×10−4–9×10−1 m2s−1, respectively, whereas specific storage values are generally~1×10−6 m−1. The values are fairly consistent through time, reasonable given lithology, and are comparable to other regional studies. For one borehole, values are also comparable to those determined with traditional aquifer test data. In contrast with previous determinations of the high-frequency poroelastic response to seismic waves, no obvious spatial trends in hydrogeologic properties determined from long-wavelength tidal perturbations are observed. Within the recurring time-series estimates, only one borehole exhibits clear permeability enhancement by earthquakes, whereas nearby boreholes with similar lithology and hydrogeologic property values do not. This highlights the variable susceptibility of rocks to permeability enhancement. Together, these results provide quantitative constraints useful for models of large-scale groundwater flow around large fault systems and the potential hydrologic influence on deformation and fault slip behavior.

Continuous synthesis of stable ferrocene nanoparticles using a self-aligned coaxial turbulent jet mixer

Ferrocene nanoparticles possess an outstanding characteristic as a drug delivery carrier, in being able to trigger on-demand release of drugs in a specific condition with reactive oxygen species (ROS). However, due to the limitation of the conventional bulk nanoprecipitation method, uniform and highly stable nanoparticles have still been difficult to develop. In this study, we developed device-mediated ferrocene nanoparticles (D-FNPs) with highly controlled uniform size and long-term stability through a flash nanoprecipitation method using a self-aligned coaxial turbulent jet mixer. The self-aligned coaxial turbulent jet mixer could be easily assembled using commercial tube fittings, which enabled the coaxial self-alignment of fluidic parts. In addition, by utilizing diaphragm pumps and pulsation dampers for the control of fluid flow, the coaxial turbulent jet mixer could be operated in a fully continuous manner. Thus, the D-FNPs could be prepared in a continuous manner with a high production rate of 633 mg/min. The D-FNPs were highly stable in aqueous media for 3 months. In addition, after lyophilization without any cryoprotectants, the D-FNPs exhibited stable dispersion in aqueous solution. Importantly, the D-FNPs maintained their original outstanding ROS-responsive characteristics, while showing no cytotoxicity.

Microengineered 3D Collagen Gels with Independently Tunable Fiber Anisotropy and Directionality.

Cellular processes, including differentiation, proliferation, and migration, have been linked to the alignment (anisotropy) and orientation (directionality) of collagen fibers in the native extracellular matrix (ECM). Given the critical role that biophysical cell-matrix interactions play in regulating biological functions, several microfluidic-based methods have been used to establish 3D collagen gels with defined fiber properties; these gels have helped to establish quantitative relationships between structural ECM cues and observed cell responses. Although existing microfluidic fabrication methods provide excellent definition over collagen fiber anisotropy, they have not demonstrated the independent control over fiber anisotropy and directionality necessary to replicate in vivo collagen architecture. Therefore, to advance collagen microengineering capabilities, we present a user-friendly technology platform that uses controlled fluid flows within a non-uniform microfluidic channel network to create collagen landscapes that can be tuned as a function of extensional strain rate. Herein, we demonstrate capabilities to i) control the degree of fiber anisotropy, ii) create spatial gradients in fiber anisotropy, iii) independently define fiber directionality, and iv) generate multi-material interfaces within a 3D environment. We then address the practical issue of integrating cells into microfluidic systems by using a peel-off template technique to provide direct access to microengineered collagen gels, and demonstrate that cells respond to the defined properties of the landscape. Finally, the platform's modular capability is highlighted by integrating a sub-micrometer thick porous parylene membrane onto the microengineered collagen as a method to define cell-substrate interactions.

Design of a Fractional Order PID Controller for Electric Hydraulic Actuator

Electric hydraulic actuators are more used especially in industries that demand high levels of accuracy. A common problem with this type of actuator is consistency in fluid flow control. PID controllers can accelerate the achievement of defined output values, eliminate offsets, and reduce maximum overshoots but result in considerable errors. Therefore, it is necessary to design controllers that can reduce errors significantly. In this research, a Fractional Order PID controller is developed to reduce maximum overshoots and steady state. Unlike conventional PID controllers that have three parameters, in the Fractional Order PID controller, there are extra two parameters of the λ and μ. The parameters were selected using the Ziegler Nichols method with a 1st order approach with a delay time. Meanwhile, the λ and μ parameters were selected the best value to make the system response better. The results of the design of the Fractional Order PID controller were evaluated using matlab simulation. The simulation results showed that the Fractional Order PID controller was able to reduce the steady state error response by 0.5 %, and the maximum overshoots by 17.4 %. From this result, it can be noted that the Fractional Order PID controller is better than conventional PID.

Control of oviductal fluid flow by the G-protein coupled receptor Adgrd1 is essential for murine embryo transit

Dysfunction of embryo transport causes ectopic pregnancy which affects approximately 2% of conceptions in the US and Europe, and is the most common cause of pregnancy-related death in the first trimester. Embryo transit involves a valve-like tubal-locking phenomenon that temporarily arrests oocytes at the ampullary-isthmic junction (AIJ) where fertilisation occurs, but the mechanisms involved are unknown. Here we show that female mice lacking the orphan adhesion G-protein coupled receptor Adgrd1 are sterile because they do not relieve the AIJ restraining mechanism, inappropriately retaining embryos within the oviduct. Adgrd1 is expressed on the oviductal epithelium and the post-ovulatory attenuation of tubal fluid flow is dysregulated in Adgrd1-deficient mice. Using a large-scale extracellular protein interaction screen, we identified Plxdc2 as an activating ligand for Adgrd1 displayed on cumulus cells. Our findings demonstrate that regulating oviductal fluid flow by Adgrd1 controls embryo transit and we present a model where embryo arrest at the AIJ is due to the balance of abovarial ciliary action and the force of adovarial tubal fluid flow, and in wild-type oviducts, fluid flow is gradually attenuated through Adgrd1 activation to enable embryo release. Our findings provide important insights into the molecular mechanisms involved in embryo transport in mice.

Multiscale characterisation of chimneys/pipes: Fluid escape structures within sedimentary basins

Evaluation of seismic reflection data has identified the presence of fluid escape structures cross-cutting overburden stratigraphy within sedimentary basins globally. Seismically-imaged chimneys/pipes are considered to be possible pathways for fluid flow, which may hydraulically connect deeper strata to the seabed. The properties of fluid migration pathways through the overburden must be constrained to enable secure, long-term subsurface carbon dioxide (CO2) storage. We have investigated a site of natural active fluid escape in the North Sea, the Scanner pockmark complex, to determine the physical characteristics of focused fluid conduits, and how they control fluid flow. Here we show that a multi-scale, multi-disciplinary experimental approach is required for complete characterisation of fluid escape structures. Geophysical techniques are necessary to resolve fracture geometry and subsurface structure (e.g., multi-frequency seismics) and physical parameters of sediments (e.g., controlled source electromagnetics) across a wide range of length scales (m to km). At smaller (mm to cm) scales, sediment cores were sampled directly and their physical and chemical properties assessed using laboratory-based methods. Numerical modelling approaches bridge the resolution gap, though their validity is dependent on calibration and constraint from field and laboratory experimental data. Further, time-lapse seismic and acoustic methods capable of resolving temporal changes are key for determining fluid flux. Future optimisation of experiment resource use may be facilitated by the installation of permanent seabed infrastructure, and replacement of manual data processing with automated workflows. This study can be used to inform measurement, monitoring and verification workflows that will assist policymaking, regulation, and best practice for CO2 subsurface storage operations.

A 3D hydrodynamic flow-focusing device for cell sorting

Optical-based microfluidic cell sorting has become increasingly attractive for applications in life and environmental sciences due to its ability of sophisticated cell handling in flow. The majority of these microfluidic cell sorting devices employ two-dimensional fluid flow control strategies, which lack the ability to manipulate the position of cells arbitrarily for precise optical detection, therefore resulting in reduced sorting accuracy and purity. Although three-dimensional (3D) hydrodynamic devices have better flow-focusing characteristics, most lack the flexibility to arbitrarily position the sample flow in each direction. Thus, there have been very few studies using 3D hydrodynamic flow focusing for sorting. Herein, we designed a 3D hydrodynamic focusing sorting platform based on independent sheath flow-focusing and pressure-actuated switching. This design offers many advantages in terms of reliable acquisition of weak Raman signals due to the ability to precisely control the speed and position of samples in 3D. With a proof-of-concept demonstration, we show this 3D hydrodynamic focusing-based sorting device has the potential to reach a high degree of accuracy for Raman activated sorting.