Dynamic control of particle separation in deterministic lateral displacement separator with viscoelastic fluids

Using symmetry to control viscoelastic waves in pillar arrays

Solutions of macromolecules exhibit viscoelastic properties and unlike Newtonian fluids, they may break time-reversal symmetry at low Reynolds numbers resulting in elastic turbulence. Furthermore, under some conditions, instead of the chaotic turbulence, the result is large-scale waves in the form of cyclic spatial and temporal concentration variations, as has been shown for macromolecular DNA flowing in microfluidic pillar arrays. We here demonstrate how altering the symmetry of the individual pillars can be used to influence the symmetry of these waves. We control the extent of instabilities in viscoelastic flow by leveraging the effects of the symmetry of the pillars on the waves, demonstrating suppressed viscoelastic fluctuations with relevance for transport and sorting applications, or conversely opening up for enhanced viscoelasticity-mediated mixing. The onset of waves, which changes flow resistance, occurs at different Deborah numbers for flow in different directions through the array of triangular pillars, thus breaking the symmetry of the flow resistance along the device, opening up for using the occurrence of the waves to construct a fluidic diode.

Short and long-range cyclic patterns in flows of DNA solutions in microfluidic obstacle arrays

We observe regular patterns emerging across multiple length scales with high-concentration DNA solutions in microfluidic pillar arrays at low Reynolds numbers and high Deborah numbers. Interacting vortices between pillars lead to long-range order in the form of large travelling waves consisting of DNA at high concentration and extension. Waves are formed in quadratic arrays of pillars, while randomizing the position of the pillar in each unit cell of a quadratic array leads to suppression of the long-range patterns. We find that concentrations exceeding the overlap concentration of the DNA enables the waves, and exploring the behavior of the waves as a function of flow rate, buffer composition, concentration and molecular length, we identify elastic effects as central to the origin of the waves. Our work may not only help increase the low throughput that often limits sample processing in microfluidics, it may also provide a platform for further studies of the underlying viscoelastic mechanisms.

Tunable deterministic lateral displacement of particles flowing through thermo-responsive hydrogel micropillar arrays

Deterministic lateral displacement (DLD) is a promising technology that allows for the continuous and the size-based separation of suspended particles at a high resolution through periodically arrayed micropillars. In conventional DLD, the critical diameter (D_c), which determines the migration mode of a particle of a particular size, is fixed by the device geometry. Here, we propose a novel DLD that uses the pillars of a thermo-responsive hydrogel, poly(N-isopropylacrylamide) (PNIPAM) to flexibly tune the D_c value. Upon heating and cooling, the PNIPAM pillars in the aqueous solution shrink and swell because of their hydrophobic-hydrophilic phase transitions as the temperature varies. Using the PNIPAM pillars confined in a poly(dimethylsiloxane) microchannel, we demonstrate continuous switching of particle (7-μm beads) trajectories (displacement or zigzag mode) by adjusting the D_c through temperature control of the device on a Peltier element. Further, we perform on/off operation of the particle separation (7-μm and 2-μm beads) by adjusting the D_c values.

High-Throughput Separation of Long DNA in Deterministic Lateral Displacement Arrays

Length-based separation of DNA remains as relevant today as when gel electrophoresis was introduced almost 100 years ago. While new, long-read genomics technologies have revolutionised accessibility to powerful genomic data, the preparation of samples has not proceeded at the same pace, with sample preparation often constituting a considerable bottleneck, both in time and difficulty. Microfluidics holds great potential for automated, sample-to-answer analysis via the integration of preparatory and analytical steps, but for this to be fully realised, more versatile, powerful and integrable unit operations, such as separation, are essential. We demonstrate the displacement and separation of DNA with a throughput that is one to five orders of magnitude greater than other microfluidic techniques. Using a device with a small footprint (23 mm × 0.5 mm), and with feature sizes in the micrometre range, it is considerably easier to fabricate than parallelized nano-array-based approaches. We show the separation of 48.5 kbp and 166 kbp DNA strands achieving a significantly improved throughput of 760 ng/h, compared to previous work and the separation of low concentrations of 48.5 kbp DNA molecules from a massive background of sub 10 kbp fragments. We show that the extension of DNA molecules at high flow velocities, generally believed to make the length-based separation of long DNA difficult, does not place the ultimate limitation on our method. Instead, we explore the effects of polymer rotations and intermolecular interactions at extremely high DNA concentrations and postulate that these may have both negative and positive influences on the separation depending on the detailed experimental conditions.

Microfluidics for detection of exosomes and microRNAs in cancer: State of the art

Exosomes are small extracellular vesicles with sizes ranging from 30-150 nanometers that contain proteins, lipids, mRNAs, microRNAs, and double-stranded DNA derived from the cells of origin. Exosomes can be taken up by target cells, acting as a means of cell-to-cell communication. The discovery of these vesicles in body fluids and their participation in cell communication has led to major breakthroughs in diagnosis, prognosis, and treatment of several conditions (e.g., cancer). However, conventional isolation and evaluation of exosomes and their microRNA content suffers from high cost, lengthy processes, difficult standardization, low purity, and poor yield. The emergence of microfluidics devices with increased efficiency in sieving, trapping, and immunological separation of small volumes could provide improved detection and monitoring of exosomes involved in cancer. Microfluidics techniques hold promise for advances in development of diagnostic and prognostic devices. This review covers ongoing research on microfluidics devices for detection of microRNAs and exosomes as biomarkers and their translation to point-of-care and clinical applications.

The Effects of Viscoelasticity on Droplet Migration on Surfaces with Wettability Gradients

A finite-volume method based on the OpenFOAM is used to numerically study the factors affecting the migration of viscoelastic droplets on rigid surfaces with wettability gradients. Parameters investigated include droplet size, relaxation time, solvent viscosity, and polymer viscosity of the liquid comprising droplets. The wettability gradient is imposed numerically by assuming a linear change in the contact angle along the substrate. As reported previously for Newtonian droplets, the wettability gradient induces spontaneous migration from hydrophobic to hydrophilic region on the substrate. The migration of viscoelastic droplets reveals the increase in the migration speed and distance with the increase in the Weissenberg number. The increase in droplet size also shows the increase in both the migration speed and distance. The increase in polymer viscosity exhibits the increase in migration speed but the decrease in migration distance.

The Effect of Surface Wettability on Viscoelastic Droplet Dynamics under Electric Fields

The effects of surface wettability and viscoelasticity on the dynamics of liquid droplets under an electric field are studied experimentally. A needle-plate electrode system is used as the power source to polarize a dielectric plate by the corona discharge emitted at the needle electrode, creating a new type of steerable electric field realized. The dynamics of droplets between the dielectric plate and a conductive substrate include three different phenomena: equilibrium to a stationary shape on substrates with higher wettability, deformation to form a bridge between the top acrylic plate and take-off on the substrates with lower wettability. Viscoelastic droplets differ from water in the liquid bridge and takeoff phenomena in that thin liquid filaments appear in viscoelastic droplets, not observed for Newtonian droplets. The equilibrated droplet exhibits more pronounced heights for Newtonian droplets compared to viscoelastic droplets, with a decrease in height with the increase in the concentration of the elastic constituent in the aqueous solution. In the take-off phenomenon, the time required for the droplet to contact the upper plate decreases with the concentration of the elastic constituent increases. It is also found that the critical voltage required for the take-off phenomenon to occur decreases as the elasticity increases.

Lubrication Force Saturation Matters for the Critical Separation Size of the Non-Colloidal Spherical Particle in the Deterministic Lateral Displacement Device

Deterministic lateral displacement (DLD) is a popular technique for separating micro-scale and nano-scale particles continuously. In this paper, an efficient three-dimensional fictitious domain method is developed for the direct numerical simulation of the motion of a non-colloidal spherical particle in the DLD device (i.e., cylinder array), based on substantial modification of our previous FD method. A combination of the fast Fourier transformation (FFT) and a tri-diagonal solver is developed to efficiently solve the pressure Poisson equation for a DLD unit with a shifted periodic boundary condition in the streamwise direction. The lubrication force correction is adopted in the fictitious domain method to correct the unresolved hydrodynamic force when the particle is close to the cylinder with the gap distance below one mesh, and the lubrication force is assumed to saturate at a smaller critical gap distance as a result of the surface roughness effect. The proposed method is then employed to investigate the effect of the critical gap distance of the lubrication force saturation on the motion mode (i.e., separation size) of the particle in the DLD device. Our results indicate that the lubrication force saturation is important to the particle critical separation size, and a smaller saturation distance generally makes the particle more prone to the zigzag mode.

Simulative Investigation of Different DLD Microsystem Designs with Increased Reynolds Numbers Using a Two-Way Coupled IBM-CFD/6-DOF Approach

Deterministic lateral displacement (DLD) microsystems are suitable for the size fractionation of particle suspensions in the size range of 0.1 to 10 µm. To be able to fractionate real particles beyond a laboratory scale, these systems have to be designed for higher throughputs. High flow resistances and increasing the clogging of the systems impose substantial challenges for industrial operation. Simulative parameter studies are suitable for improving the design of the systems; for example, the position and shape of the posts. A high-resolution, two-way coupled 6-DOF CFD-DEM approach was used to study the flow and particle behavior of different post shapes (circular and triangular) and post sizes at different Reynolds numbers. The results were compared with the classical first streamline width theory. It was shown that the streamline theory does not account for all effects responsible for the separation. Furthermore, a shift in the critical particle diameter to smaller values could be obtained when increasing the Reynolds number and also when using triangular posts with reduced post sizes compared to the post spacing. These findings can help to improve the efficiency of the systems as the post spacing could be extended, thus reducing the flow resistance and the probability of clogging.

Geometric structure design of passive label-free microfluidic systems for biological micro-object separation

Passive and label-free microfluidic devices have no complex external accessories or detection-interfering label particles. These devices are now widely used in medical and bioresearch applications, including cell focusing and cell separation. Geometric structure plays the most essential role when designing a passive and label-free microfluidic chip. An exquisitely designed geometric structure can change particle trajectories and improve chip performance. However, the geometric design principles of passive and label-free microfluidics have not been comprehensively acknowledged. Here, we review the geometric innovations of several microfluidic schemes, including deterministic lateral displacement (DLD), inertial microfluidics (IMF), and viscoelastic microfluidics (VEM), and summarize the most creative innovations and design principles of passive and label-free microfluidics. We aim to provide a guideline for researchers who have an interest in geometric innovations of passive label-free microfluidics.

Progress of Microfluidic Continuous Separation Techniques for Micro-/Nanoscale Bioparticles

Separation of micro- and nano-sized biological particles, such as cells, proteins, and nucleotides, is at the heart of most biochemical sensing/analysis, including in vitro biosensing, diagnostics, drug development, proteomics, and genomics. However, most of the conventional particle separation techniques are based on membrane filtration techniques, whose efficiency is limited by membrane characteristics, such as pore size, porosity, surface charge density, or biocompatibility, which results in a reduction in the separation efficiency of bioparticles of various sizes and types. In addition, since other conventional separation methods, such as centrifugation, chromatography, and precipitation, are difficult to perform in a continuous manner, requiring multiple preparation steps with a relatively large minimum sample volume is necessary for stable bioprocessing. Recently, microfluidic engineering enables more efficient separation in a continuous flow with rapid processing of small volumes of rare biological samples, such as DNA, proteins, viruses, exosomes, and even cells. In this paper, we present a comprehensive review of the recent advances in microfluidic separation of micro-/nano-sized bioparticles by summarizing the physical principles behind the separation system and practical examples of biomedical applications.

Inertial microfluidics for high-throughput cell analysis and detection: a review

Since it was first proposed in 2007, inertial microfluidics has been extensively studied in terms of theory, design, fabrication, and application. In recent years, with the rapid development of microfabrication technologies, a variety of channel structures that can focus, concentrate, separate, and capture bioparticles or fluids have been designed and manufactured to extend the range of potential biomedical applications of inertial microfluidics. Due to the advantages of high throughput, simplicity, and low device cost, inertial microfluidics is a promising candidate for rapid sample processing, especially for large-volume samples with low-abundance targets. As an approach to cellular sample pretreatment, inertial microfluidics has been widely employed to ensure downstream cell analysis and detection. In this review, a comprehensive summary of the application of inertial microfluidics for high-throughput cell analysis and detection is presented. According to application areas, the recent advances can be sorted into label-free cell mechanical phenotyping, sheathless flow cytometric counting, electrical impedance cytometer, high-throughput cellular image analysis, and other methods. Finally, the challenges and prospects of inertial microfluidics for cell analysis and detection are summarized.

Deterministic Sorting of Submicrometer Particles and Extracellular Vesicles Using a Combined Electric and Acoustic Field

Sorting of extracellular vesicles has important applications in early stage diagnostics. Current exosome isolation techniques, however, suffer from being costly, having long processing times, and producing low purities. Recent work has shown that active sorting via acoustic and electric fields are useful techniques for microscale separation activities, where combining these has the potential to take advantage of multiple force mechanisms simultaneously. In this work, we demonstrate an approach using both electrical and acoustic forces to manipulate bioparticles and submicrometer particles for deterministic sorting, where we find that the concurrent application of dielectrophoretic (DEP) and acoustophoretic forces decreases the critical diameter at which particles can be separated. We subsequently utilize this approach to sort subpopulations of extracellular vesicles, specifically exosomes (<200 nm) and microvesicles (>300 nm). Using our combined acoustic/electric approach, we demonstrate exosome purification with more than 95% purity and 81% recovery, well above comparable approaches.

Nonlinear microfluidics: device physics, functions, and applications

The microfluidic flow is typically laminar due to the dominant viscous effects. At Reynolds numbers far below 1 (Re ≪ 1), the fluid inertia can be neglected. For the steady flow of incompressible Newtonian fluids, it approaches linear Stokes flow. At intermediate Re, there exists a weak-inertia flow regime where secondary flows such as Dean vortices are accessible for microfluidic manipulations. Apart from the fluid inertia, other nonlinear factors such as the non-Newtonian fluid properties, concurrent flow of dissimilar fluids, compliant fluidic structures and stimuli-responsive materials can also cause intriguing flow behaviours. Through proper designs, they can be applied for a variety of microfluidic components including mixers, valves, oscillators, stabilizers and auto-regulators etc., greatly enriching the microfluidic flow control and manipulation strategies. Due to its unique working characteristics and advantages, nonlinear microfluidics has increasingly attracted extensive attention. This review presents a systematic survey on this subject. The designs of typical nonlinear microfluidic devices, their working mechanisms, key applications, and the perspective of their future developments will be discussed. The nonlinear microfluidic techniques are believed to play an essential role in the next generation of highly-integrated, automated, and intelligent microfluidics.

Directional locking effects for active matter particles coupled to a periodic substrate

Directional locking occurs when a particle moving over a periodic substrate becomes constrained to travel along certain substrate symmetry directions. Such locking effects arise for colloids and superconducting vortices moving over ordered substrates when the direction of the external drive is varied. Here we study the directional locking of run-and-tumble active matter particles interacting with a periodic array of obstacles. In the absence of an external biasing force, we find that the active particle motion locks to various symmetry directions of the substrate when the run time between tumbles is large. The number of possible locking directions depends on the array density and on the relative sizes of the particles and the obstacles. For a square array of large obstacles, the active particle only locks to the x, y, and 45^{∘} directions, while for smaller obstacles, the number of locking angles increases. Each locking angle satisfies θ=arctan(p/q), where p and q are integers, and the angle of motion can be measured using the ratio of the velocities or the velocity distributions in the x and y directions. When a biasing driving force is applied, the directional locking behavior is affected by the ratio of the self-propulsion force to the biasing force. For large biasing, the behavior resembles that found for directional locking in passive systems. For large obstacles under biased driving, a trapping behavior occurs that is nonmonotonic as a function of increasing run length or increasing self-propulsion force, and the trapping diminishes when the run length is sufficiently large.

Deterministic Lateral Displacement: Challenges and Perspectives

The advent of microfluidics in the 1990s promised a revolution in multiple industries from healthcare to chemical processing. Deterministic lateral displacement (DLD) is a continuous-flow microfluidic particle separation method discovered in 2004 that has been applied successfully and widely to the separation of blood cells, yeast, spores, bacteria, viruses, DNA, droplets, and more. Deterministic lateral displacement is conceptually simple and can deliver consistent performance over a wide range of flow rates and particle concentrations. Despite wide use and in-depth study, DLD has not yet been fully elucidated or optimized, with different approaches to the same problem yielding varying results. We endeavor here to provide up-to-date expert opinion on the state-of-art and current fundamental, practical, and commercial challenges with DLD as well as describe experimental and modeling opportunities. Because these challenges and opportunities arise from constraints on hydrodynamics, fabrication, and operation at the micro- and nanoscale, we expect this Perspective to serve as a guide for the broader micro- and nanofluidic community to identify and to address open questions in the field.

Collective effects and pattern formation for directional locking of disks moving through obstacle arrays

We examine directional locking effects in an assembly of disks driven through a square array of obstacles as the angle of drive rotates from 0^{∘} to 90^{∘}. For increasing disk densities, the system exhibits a series of different dynamic patterns along certain locking directions, including one-dimensional or multiple-row chain phases and density-modulated phases. For nonlocking driving directions, the disks form disordered patterns or clusters. When the obstacles are small or far apart, a large number of locking phases appear; however, as the number of disks increases, the number of possible locking phases drops due to the increasing frequency of collisions between the disks and obstacles. For dense arrays or large obstacles, we find an increased clogging effect in which immobile and moving disks coexist.

Deterministic Lateral Displacement-Based Separation of Magnetic Beads and Its Applications of Antibody Recognition

This work presents a magnetic-driven deterministic lateral displacement (m-DLD) microfluidic device. A permanent magnet located at the outlet of the microchannel was used to generate the driving force. Two stages of mirrored round micropillar array were designed for the separation of magnetic beads with three different sizes in turn. The effects of the forcing angle and the inlet width of the micropillar array on the separating efficiency were studied. The m-DLD device with optimal structure parameters shows that the separating efficiencies for the 10 μm, 20 μm and 40 μm magnetic beads are 87%, 89% and 94%, respectively. Furthermore, this m-DLD device was used for antibody recognition and separation among a mixture solution of antibodies. The trajectories of different kinds of magnetic beads coupled with different antigens showed that the m-DLD device could realize a simple and low-cost diagnostic test.

Numerical Study on the Characteristics of Boger Type Viscoelastic Fluid Flow in a Micro Cross-Slot under Sinusoidal Stimulation

The cross-slot geometry plays an important role in the study of nonlinear effects of viscoelastic fluids. The flow of viscoelastic fluid in a micro cross-slot with a high channel aspect ratio (AR, the ratio of channel depth to width) can be divided into three types, which are symmetric flow, steady-state asymmetric flow and time-dependent flow under the inlet condition with a constant velocity. However, the flow pattern of a viscoelastic fluid in the cross-slot when a stimulation is applied at inlets has been rarely reported. In this paper, the response of cross-slot flow under an external sinusoidal stimulation is studied by numerical simulations of a two-dimensional model representing the geometry with a maximum limit of AR. For the cases under constant inlet velocity conditions, three different flow patterns occur successively with the increase of Weissenberg number (Wi). For the cases under sinusoidal varying inlet velocity conditions, when the stimulation frequency is far away from the natural frequency of a viscoelastic fluid, the frequency spectrum of velocity fluctuation field shows the characteristics of a fundamental frequency and several harmonics. However, the harmonic frequency disappears when the stimulation frequency is close to the natural frequency of the viscoelastic fluid. Besides, the flow pattern shows spatial symmetry and changes with time. In conclusion, the external stimulation has an effect on the flow pattern of viscoelastic fluid in the 2D micro cross-slot channel, and a resonance occurs when the stimulation frequency is close to the natural frequency of the fluid.

Sequential Cell-Processing System by Integrating Hydrodynamic Purification and Dielectrophoretic Trapping for Analyses of Suspended Cancer Cells

Microfluidic devices employing dielectrophoresis (DEP) have been widely studied and applied in the manipulation and analysis of single cells. However, several pre-processing steps, such as the preparation of purified target samples and buffer exchanges, are necessary to utilize DEP forces for suspended cell samples. In this paper, a sequential cell-processing device, which is composed of pre-processing modules that employ deterministic lateral displacement (DLD) and a single-cell trapping device employing an electroactive microwell array (EMA), is proposed to perform the medium exchange followed by arraying single cells sequentially using DEP. Two original microfluidic devices were efficiently integrated by using the interconnecting substrate containing rubber gaskets that tightly connect the inlet and outlet of each device. Prostate cancer cells (PC3) suspended in phosphate-buffered saline buffer mixed with microbeads were separated and then resuspended into the DEP buffer in the integrated system. Thereafter, purified PC3 cells were trapped in a microwell array by using the positive DEP force. The achieved separation and trapping efficiencies exceeded 94% and 93%, respectively, when using the integrated processing system. This study demonstrates an integrated microfluidic device by processing suspended cell samples, without the requirement of complex preparation steps.

Continuous separation of fungal spores in a microfluidic flow focusing device

The research of fungi is of great importance in a number of fields, such as environmental and healthcare studies. While there are a large number of optical and molecular methods available for characterization and identification of fungi and their spores, their isolation is still conducted using slow and labor-intensive methods. Here, we develop a microfluidic device for the continuous separation of fungal spores from other eukaryotic cells. The spores were separated through the microfluidic device by expanding pinched flow fractionation (PFF) containing the spores, achieving a spatial separation perpendicular to the flow direction according to the spore size. Further branch flow fractionation (BFF) and co-flow of a Newtonian and viscoelastic fluid were used to enhance the separation performance. Using this microfluidic device, we demonstrated the separation of two different types of fungal spores and further separation of fungal spores from eukaryotic cells with a separation efficiency of above 90%. Compared to the existing conventional methods, our microfluidic flow focusing device requires little manual handling and uses small amounts of samples without any pre-treatment steps of the samples.

Manipulation of micro- and nanoparticles in viscoelastic fluid flows within microfluid systems

Manipulation of micro- and nanoparticles in complex biofluids is highly demanded in most biological and biomedical applications. A significant number of microfluidic platforms have been developed for inexpensive, rapid, accurate, and efficient particle manipulation. Due to the enormous potential of viscoelastic fluids (VEFs) for particle manipulation, various emerging microfluidic-based VEFs techniques have been presented over the last decade. This review provides an intuitive understanding of VEF physics for particle separation in different microchannel geometries. Besides, active and passive VEF methods are critically reviewed, highlighting the potential and practical challenges of each technique for particle/cell focusing, sorting, and separation. The outcome of this study could enable recognizing deliverable VEF technology with the promising prospect in the manipulation of submicron biological samples (e.g., exosomes, DNA, and proteins).

A Review on Deterministic Lateral Displacement for Particle Separation and Detection

The separation and detection of particles in suspension are essential for a wide spectrum of applications including medical diagnostics. In this field, microfluidic deterministic lateral displacement (DLD) holds a promise due to the ability of continuous separation of particles by size, shape, deformability, and electrical properties with high resolution. DLD is a passive microfluidic separation technique that has been widely implemented for various bioparticle separations from blood cells to exosomes. DLD techniques have been previously reviewed in 2014. Since then, the field has matured as several physics of DLD have been updated, new phenomena have been discovered, and various designs have been presented to achieve a higher separation performance and throughput. Furthermore, some recent progress has shown new clinical applications and ability to use the DLD arrays as a platform for biomolecules detection. This review provides a thorough discussion on the recent progress in DLD with the topics based on the fundamental studies on DLD models and applications for particle separation and detection. Furthermore, current challenges and potential solutions of DLD are also discussed. We believe that a comprehensive understanding on DLD techniques could significantly contribute toward the advancements in the field for various applications. In particular, the rapid, low-cost, and high-throughput particle separation and detection with DLD have a tremendous impact for point-of-care diagnostics.

Tunable Mass Separation via Negative Mobility

A prerequisite for isolating diseased cells requires a mechanism for effective mass-based separation. This objective, however, is generally rather challenging because typically no valid correlation exists between the size of the particles and their mass value. We consider an inertial Brownian particle moving in a symmetric periodic potential and subjected to an externally applied unbiased harmonic driving in combination with a constant applied bias. In doing so, we identify a most efficient separation scheme which is based on the anomalous transport feature of negative mobility, meaning that the immersed particles move in the direction opposite to the acting bias. This work is the first of its kind in demonstrating a tunable separation mechanism in which the particle mass targeted for isolation is effectively controlled over a regime of nearly 2 orders of mass magnitude upon changing solely the frequency of the external harmonic driving. This approach may provide mass selectivity required in present and future separation of a diversity of nano- and microsized particles of either biological or synthetic origin.

Separation of Biological Particles in a Modular Platform of Cascaded Deterministic Lateral Displacement Modules

Deterministic lateral displacement (DLD) has been extensively implemented in the last decade for size-based sample preparation, owing to its high separation performances for a wide range of particle dimensions. However, separating particles from 1 μm to 10 μm in one single DLD device is challenging because of the required diversity of pillar dimensions and inherent fabrication issues. This paper presents an alternative approach to achieve the extraction of E. coli bacteria from blood samples spiked with prostate cancer cells. Our approach consists in cascading individual DLD devices in a single automated platform, using flexible chambers that successively collect and inject the sample between each DLD stage without any external sample manipulation. Operating DLD separations independently enables to maximize the sorting efficiency at each step, without any disturbance from downstream stages. The proposed two-step automated protocol is applied to the separation of three types of components (bacteria, blood particles and cancer cells), with a depletion yield of 100% for cancer cells and 93% for red blood cells. This cascaded approach is presented for the first time with two DLD modules and is upscalable to improve the dynamic range of currently available DLD devices.