Concurrent isolation of lymphocytes and granulocytes using prefocused free flow acoustophoresis

Label-free microfluidic isolation of functional and viable lymphocytes from peripheral blood mononuclear cells

The separation of peripheral blood mononuclear cells (PBMCs) into constituent blood cell types is a vital step to obtain immune cells for autologous cell therapies. The ability to separate PBMCs using label-free microfluidic techniques, based on differences in biomechanical properties, can have a number of benefits over other conventional techniques, including lower cost, ease of use, and avoidance of animal-derived labeling antibodies. Here, we report a microfluidic device that uses compressive diagonal ridges to separate PBMCs into highly pure samples of viable and functional lymphocytes. The technique utilizes the differences in the biophysical properties of PBMC sub-populations to direct the lymphocytes and monocytes into separate outlets. The biophysical properties of the monocytes and lymphocytes from healthy donors were first characterized using atomic force microscopy. Lymphocytes were found to be significantly stiffer than monocytes, with a mean cell stiffness of 1495 and 931 Pa, respectively. The differences in biophysical properties resulted in distinct trajectories through the microchannel terminating at different outlets, resulting in a lymphocyte sample with purity and viability both greater than 96% with no effect on the cells' ability to produce interferon gamma, a cytokine crucial for innate and adaptive immunity.

Acoustofluidics - changing paradigm in tissue engineering, therapeutics development, and biosensing

For more than 70 years, acoustic waves have been used to screen, diagnose, and treat patients in hundreds of medical devices. The biocompatible nature of acoustic waves, their non-invasive and contactless operation, and their compatibility with wide visualization techniques are just a few of the many features that lead to the clinical success of sound-powered devices. The development of microelectromechanical systems and fabrication technologies in the past two decades reignited the spark of acoustics in the discovery of unique microscale bio applications. Acoustofluidics, the combination of acoustic waves and fluid mechanics in the nano and micro-realm, allowed researchers to access high-resolution and controllable manipulation and sensing tools for particle separation, isolation and enrichment, patterning of cells and bioparticles, fluid handling, and point of care biosensing strategies. This versatility and attractiveness of acoustofluidics have led to the rapid expansion of platforms and methods, making it also challenging for users to select the best acoustic technology. Depending on the setup, acoustic devices can offer a diverse level of biocompatibility, throughput, versatility, and sensitivity, where each of these considerations can become the design priority based on the application. In this paper, we aim to overview the recent advancements of acoustofluidics in the multifaceted fields of regenerative medicine, therapeutic development, and diagnosis and provide researchers with the necessary information needed to choose the best-suited acoustic technology for their application. Moreover, the effect of acoustofluidic systems on phenotypic behavior of living organisms are investigated. The review starts with a brief explanation of acoustofluidic principles, the different working mechanisms, and the advantages or challenges of commonly used platforms based on the state-of-the-art design features of acoustofluidic technologies. Finally, we present an outlook of potential trends, the areas to be explored, and the challenges that need to be overcome in developing acoustofluidic platforms that can echo the clinical success of conventional ultrasound-based devices.

Inertia-Acoustophoresis Hybrid Microfluidic Device for Rapid and Efficient Cell Separation

In this paper, we proposed an integrated microfluidic device that could demonstrate the non-contact, label-free separation of particles and cells through the combination of inertial microfluidics and acoustophoresis. The proposed device integrated two microfluidic chips which were a PDMS channel chip on top of the silicon-based acoustofluidic chip. The PDMS chip worked by prefocusing the particles/cells through inducing the inertial force of the channel structure. The connected acoustofluidic chips separated particles based on their size through an acoustic radiation force. In the serpentine-shaped PDMS chip, particles formed two lines focusing in the channel, and a trifugal-shaped acoustofluidic chip displaced and separated particles, in which larger particles focused on the central channel and smaller ones moved to the side channels. The simultaneous fluidic works allowed high-efficiency particle separation. Using this novel acoustofluidic device with an inertial microchannel, the separation of particles and cells based on their size was presented and analyzed, and the efficiency of the device was shown. The device demonstrated excellent separation performance with a high recovery ratio (up to 96.3%), separation efficiency (up to 99%), and high volume rate (>100 µL/min). Our results showed that integrated devices could be a viable alternative to current cell separation based on their low cost, reduced sample consumption and high throughput capability.

Differential impedance spectra analysis reveals optimal actuation frequency in bulk mode acoustophoresis

This work reports a method to select the optimal working frequency in transversal bulk resonator acoustophoretic devices by electrical impedance measurements. The impedance spectra of acoustophoretic devices are rich in spurious resonance peaks originating from different resonance modes in the system not directly related to the channel resonance, why direct measurement of the piezoelectric transducer impedance spectra is not a viable strategy. This work presents, for the first time, that the resonance modes of microchip integrated acoustophoresis channels can be identified by sequentially measuring the impedance spectra of the acoustophoretic device when the channel is filled with two different fluids and subsequently calculate the Normalized Differential Spectrum (NDS). Seven transversal bulk resonator acoustophoretic devices of different materials and designs were tested with successful results. The developed method enables a rapid, reproducible and precise determination of the optimal working frequency.

Label-free neuroblastoma cell separation from hematopoietic progenitor cell products using acoustophoresis - towards cell processing of complex biological samples

Processing of complex cell preparations such as blood and peripheral blood progenitor cell (PBPC) transplants using label-free technologies is challenging. Transplant-contaminating neuroblastoma cells (NBCs) can contribute to relapse, and we therefore aimed to provide proof-of-principle evidence that label-free acoustophoretic separation can be applied for diagnostic NBC enrichment and removal ("purging") from human blood and PBPC products. Neuroblastoma cells spiked into blood and PBPC preparations served as model systems. Acoustophoresis enabled to enrich NBCs from mononuclear peripheral blood cells and PBPC samples with recovery rates of up to 60-97%. When aiming at high purity, NBC purities of up to 90% were realized, however, compromising recovery. Acoustophoretic purging of PBPC products allowed substantial tumour cell depletion of 1.5-2.3 log. PBPC loss under these conditions was considerable (>43%) but could be decreased to less than 10% while still achieving NBC depletion rates of 60-80%. Proliferation of cells was not affected by acoustic separation. These results provide first evidence that NBCs can be acoustically separated from blood and stem cell preparations with high recovery and purity, thus indicating that acoustophoresis is a promising technology for the development of future label-free, non-contact cell processing of complex cell products.

Scalable high-throughput acoustophoresis in arrayed plastic microchannels

Microfluidic acoustophoresis is a label-free technique that isolates a purified product from a complex mixture of cells. This technique is well-studied but thus far has lacked the throughput and device manufacturability needed for many medical and industrial uses. Scale-up of acoustofluidic devices can be more challenging than in other microfluidic systems because the channel walls are integral to the resonant behavior and coupling to neighboring channels can inhibit performance. Additionally, the increased device area needed for parallel channels becomes less practical in the silicon or glass materials usually used for acoustofluidic devices. Here, we report an acoustic separator with 12 parallel channels made entirely from polystyrene that achieves blood cell separation at a flow rate greater than 1 ml/min. We discuss the design and optimization of the device and the electrical drive parameters and compare the separation performance using channels of two different designs. To demonstrate the utility of the device, we test its ability to purify lymphocytes from apheresis product, a process that is critical to new immunotherapies used to treat blood cancers. We process a leukapheresis sample with a volume greater than 100 ml in less than 2 h in a single pass without interruption, achieving greater than 90% purity of lymphocytes, without any prepurification steps. These advances suggest that acoustophoresis could in the future aid in cell therapy bioprocessing and that further scale-up is possible.

Label-free separation of leukocyte subpopulations using high throughput multiplex acoustophoresis

Multiplex separation of mixed cell samples is required in a variety of clinical and research applications. Herein, we present an acoustic microchip with multiple outlets and integrated pre-alignment channel to enable high performance and label-free separation of three different cell or particle fractions simultaneously at high sample throughput. By implementing a new cooling system for rigorous temperature control and minimal acoustic energy losses, we were able to operate the system isothermally and sort suspensions of 3, 5 and 7 μm beads with high efficiencies (>95.4%) and purities (>96.3%) at flow rates up to 500 μL min-1 corresponding to a throughput of ∼2.5 × 106 beads per min. Also, human viable white blood cells were successfully fractionated into lymphocytes, monocytes and granulocytes with high purities of 96.5 ± 1.6%, 71.8 ± 10.1% and 98.8 ± 0.5%, respectively, as well as high efficiencies (96.8 ± 3.3%, 66.7 ± 3.2% and 99.0 ± 0.7%) at flow rates up to 100 μL min-1 (∼100 000 cells per min). By increasing the flow rate up to 300 μL min-1 (∼300 000 cells per min) both lymphocytes and granulocytes were still recovered with high purities (92.8 ± 1.9%, 98.2 ± 1 .0%), whereas the monocyte purity decreased to 20.9 ± 10.3%. The proposed isothermal multiplex acoustophoresis platform offers efficient fractionation of complex samples in a label-free and continuous manner at thus far unreached high sample throughput rates.

Applications of Acoustofluidics in Bioanalytical Chemistry

Acoustics has a broad spectrum of applications, ranging from noise cancelation to ultrasonic imaging. In the past decade, there has been increasing interest in developing acoustic-based methods for biological and biomedical applications. This Perspective summarizes the recent progress in applying acoustofluidic methods (i.e., the fusion of acoustics and microfluidics) to bioanalytical chemistry. We describe the concepts of acoustofluidics and how it can be tailored to different types of bioanalytical applications, including sample concentration, fluorescence-activated cell sorting, label-free cell/particle separation, and fluid manipulation. Examples of each application are given, and the benefits and limitations of these methods are discussed. Finally, our perspectives on the directions that developing solutions should take to address the bottlenecks in the acoustofluidic applications in bioanalytical chemistry are presented.

Resonance control of acoustic focusing systems through an environmental reference table and impedance spectroscopy

Acoustic standing waves can precisely focus flowing particles or cells into tightly positioned streams for interrogation or downstream separations. The efficiency of an acoustic standing wave device is dependent upon operating at a resonance frequency. Small changes in a system's temperature and sample salinity can shift the device's resonance condition, leading to poor focusing. Practical implementation of an acoustic standing wave system requires an automated resonance control system to adjust the standing wave frequency in response to environmental changes. Here we have developed a rigorous approach for quantifying the optimal acoustic focusing frequency at any given environmental condition. We have demonstrated our approach across a wide range of temperature and salinity conditions to provide a robust characterization of how the optimal acoustic focusing resonance frequency shifts across these conditions. To generalize these results, two microfluidic bulk acoustic standing wave systems (a steel capillary and an etched silicon wafer) were examined. Models of these temperature and salinity effects suggest that it is the speed of sound within the liquid sample that dominates the resonance frequency shift. Using these results, a simple reference table can be generated to predict the optimal resonance condition as a function of temperature and salinity. Additionally, we show that there is a local impedance minimum associated with the optimal system resonance. The integration of the environmental results for coarse frequency tuning followed by a local impedance characterization for fine frequency adjustments, yields a highly accurate method of resonance control. Such an approach works across a wide range of environmental conditions, is easy to automate, and could have a significant impact across a wide range of microfluidic acoustic standing wave systems.

High-throughput cell focusing and separation via acoustofluidic tweezers

Separation of particles and cells is an important function in many biological and biomedical protocols. Although a variety of microfluidic-based techniques have been developed so far, there is clearly still a demand for a precise, fast, and biocompatible method for separation of microparticles and cells. By combining acoustics and hydrodynamics, we have developed a method which we integrated into three-dimensional acoustofluidic tweezers (3D-AFT) to rapidly and efficiently separate microparticles and cells into multiple high-purity fractions. Compared with other acoustophoresis methods, this 3D-AFT method significantly increases the throughput by an order of magnitude, is label-free and gently handles the sorted cells. We demonstrate not only the separation of 10, 12, and 15 micron particles at a throughput up to 500 μl min-1 using this 3D-AFT method, but also the separation of erythrocytes, leukocytes, and cancer cells. This 3D-AFT method is able to meet various separation demands thus offering a viable alternative with potential for clinical applications.

An integrated microfluidic platform for size-selective single-cell trapping of monocytes from blood

Reliable separation and isolation of target single cells from bodily fluids with high purity is of great significance for an accurate and quantitative understanding of the cellular heterogeneity. Here, we describe a fully integrated single-blood-cell analysis platform capable of size-selective cell separation from a population containing a wide distribution of sizes such as diluted blood sample and highly efficient entrapment of single monocytes. The spiked single U937 cells (human monocyte cell line) are separated in sequence by two different-sized microfilters for removing large cell clumps, white blood cells, and red blood cells and then discriminated by dielectrophoretic force and isolated individually by downstream single-cell trapping arrays. When 2% hematocrit blood cells with a final ratio of 1:1000 U937 cells were introduced under the flow rate of 0.2 ml/h, 400 U937 cells were trapped sequentially and deterministically within 40 s with single-cell occupancy of up to 85%. As a proof-of-concept, we also demonstrated single monocyte isolation from diluted blood using the integrated microfluidic device. This size-selective, label-free, and live-cell enrichment microfluidic single blood-cell isolation platform for the processing of cancer and blood cells has a myriad of applications in areas such as single-cell genetic analysis, stem cell biology, point-of-care diagnostics, and cancer diagnostics.

Purification of Lymphocytes by Acoustic Separation in Plastic Microchannels

Emerging cell therapies have created new demands for instruments that will increase processing efficiency. Purification of lymphocytes prior to downstream steps of gene transfer currently relies on centrifugal separation, which has drawbacks in output sample purity and process automation. Here, we present an alternative approach to blood cell purification using acoustic forces in plastic microchannels. We provide details regarding the system's ability to purify lymphocytes relative to other blood cell types while maintaining a high overall recovery, testing performance starting from leukapheresis product, buffy coat, and whole blood. Depending on settings, the device achieves for lymphocytes up to 97% purity and up to 68% recovery, and depletes 98% of monocytes while also reducing red cells and platelets. We expect that future scale-up of our system for increased throughput will enable its incorporation in the cell therapy workflow, and that it could ultimately reduce costs and expand access for patients.

Separation efficiency maximization in acoustofluidic systems: study of the sample launch-position

The development of lab-on-chip microfluidic systems based on acoustic actuation, and in particular on the acoustophoretic force, has recently attracted significant attention from the scientific community thanks, in part, to the possibility of sample sorting on the basis of both geometrical and mechanical properties. It is commonly recognized that sample prefocusing and launch-position optimization have a substantial effect on the performance of these systems but a clear explanation of how these two parameters influence the system efficiency is still missing. In this manuscript we discuss the impact of both the sample launch position and the sample distribution at the input by the theoretical analysis of a simplified system and by numerical simulations of realistic configurations. The results show that the system performance can be greatly improved by selecting the proper microchannel dimensions and sample-launch position, offering relevant guidelines for the design of micro-acoustofluidic lab-on-chip devices.

We theoretically and numerically show how to optimize the separation-efficiency of acoustofluidic systems by a non-trivial selection of sample-injection position.

Rapid and effective enrichment of mononuclear cells from blood using acoustophoresis

Effective separation methods for fractionating blood components are needed for numerous diagnostic and research applications. This paper presents the use of acoustophoresis, an ultrasound based microfluidic separation technology, for label-free, gentle and continuous separation of mononuclear cells (MNCs) from diluted whole blood. Red blood cells (RBCs) and MNCs behave similar in an acoustic standing wave field, compromising acoustic separation of MNC from RBC in standard buffer systems. However, by optimizing the buffer conditions and thereby changing the acoustophoretic mobility of the cells, we were able to enrich MNCs relative to RBCs by a factor of 2,800 with MNC recoveries up to 88%. The acoustophoretic microchip can perform cell separation at a processing rate of more than 1 × 10⁵ cells/s, corresponding to 5 µl/min undiluted whole blood equivalent. Thus, acoustophoresis can be easily integrated with further down-stream applications such as flow cytometry, making it a superior alternative to existing MNC isolation techniques.

High-Throughput Separation of White Blood Cells From Whole Blood Using Inertial Microfluidics

White blood cells (WBCs) constitute only about 0.1% of human blood cells, yet contain rich information about the immune status of the body; thus, separation of WBCs from the whole blood is an indispensable and critical sample preparation step in many scientific, clinical, and diagnostic applications. In this paper, we developed a continuous and high-throughput microfluidic WBC separation platform utilizing the differential inertial focusing of particles in serpentine microchannels. First, separation performance of the proposed method is characterized and evaluated using polystyrene beads in the serpentine channel. The purity of 10-μm polystyrene beads is increased from 0.1% to 80.3% after two cascaded processes, with an average enrichment ratio of 28 times. Next, we investigated focusing and separation properties of Jurkat cells spiked in the blood to mimic the presence of WBCs in whole blood. Finally, separation of WBCs from human whole blood was conducted and separation purity of WBCs was measured by the flow cytometry. The results show that the purity of WBCs can be increased to 48% after two consecutive processes, with an average enrichment ratio of ten times. Meanwhile, a parallelized inertial microfluidic device was designed to provide a high processing flow rate of 288 ml/h for the diluted (×1/20) whole blood. The proposed microfluidic device can potentially work as an upstream component for blood sample preparation and analysis in the integrated microfluidic systems.

Clinical-Scale Cell-Surface-Marker Independent Acoustic Microfluidic Enrichment of Tumor Cells from Blood

Enumeration of circulating tumor cells (CTCs) predicts overall survival and treatment response in metastatic cancer, but as many commercialized assays isolate CTCs positive for epithelial cell markers alone, CTCs with little or no epithelial cell adhesion molecule (EpCAM) expression stay undetected. Therefore, CTC enrichment and isolation by label-free methods based on biophysical rather than biochemical properties could provide a more representative spectrum of CTCs. Here, we report on a clinical-scale automated acoustic microfluidic platform processing 5 mL of erythrocyte-depleted paraformaldehyde (PFA)-fixed blood (diluted 1:2) at a flow rate of 75 μL/min, recovering 43/50 (86 ± 2.3%) breast cancer cell line cells (MCF7), with 0.11% cancer cell purity and 162-fold enrichment in close to 2 h based on intrinsic biophysical cell properties. Adjustments of the voltage settings aimed at higher cancer cell purity in the central outlet provided 0.72% cancer cell purity and 1445-fold enrichment that resulted in 62 ± 8.7% cancer cell recovery. Similar rates of cancer-cell recovery, cancer-cell purity, and fold-enrichment were seen with both prostate cancer (DU145, PC3) and breast cancer (MCF7) cell line cells. We identified eosinophil granulocytes as the predominant white blood cell (WBC) contaminant (85%) in the enriched cancer-cell fraction. Processing of viable cancer cells in erythrocyte-depleted blood provided slightly reduced results as to fixed cells (77% cancer cells in the enriched cancer cell fraction, with 0.2% WBC contamination). We demonstrate feasibility of enriching either PFA-fixed or viable cancer cells with a clinical-scale acoustic microfluidic platform that can be adjusted to meet requirements for either high cancer-cell recovery or higher purity and can process 5 mL blood samples in close to 2 h.

Microfluidic Adaptation of Density-Gradient Centrifugation for Isolation of Particles and Cells

Density-gradient centrifugation is a label-free approach that has been extensively used for cell separations. Though elegant, this process is time-consuming (>30 min), subjects cells to high levels of stress (>350 g) and relies on user skill to enable fractionation of cells that layer as a narrow band between the density-gradient medium and platelet-rich plasma. We hypothesized that microfluidic adaptation of this technique could transform this process into a rapid fractionation approach where samples are separated in a continuous fashion while being exposed to lower levels of stress (<100 g) for shorter durations of time (<3 min). To demonstrate proof-of-concept, we designed a microfluidic density-gradient centrifugation device and constructed a setup to introduce samples and medium like Ficoll in a continuous, pump-less fashion where cells and particles can be exposed to centrifugal force and separated via different outlets. Proof-of-concept studies using binary mixtures of low-density polystyrene beads (1.02 g/cm³) and high-density silicon dioxide beads (2.2 g/cm³) with Ficoll–Paque (1.06 g/cm³) show that separation is indeed feasible with >99% separation efficiency suggesting that this approach can be further adapted for separation of cells.

Slanted, asymmetric microfluidic lattices as size-selective sieves for continuous particle/cell sorting

Hydrodynamic microfluidic platforms have been proven to be useful and versatile for precisely sorting particles/cells based on their physicochemical properties. In this study, we demonstrate that a simple lattice-shaped microfluidic pattern can work as a virtual sieve for size-dependent continuous particle sorting. The lattice is composed of two types of microchannels ("main channels" and "separation channels"). These channels cross each other in a perpendicular fashion, and are slanted against the macroscopic flow direction. The difference in the densities of these channels generates an asymmetric flow distribution at each intersection. Smaller particles flow along the streamline, whereas larger particles are filtered and gradually separated from the stream, resulting in continuous particle sorting. We successfully sorted microparticles based on size with high accuracy, and clearly showed that geometric parameters, including the channel density and the slant angle, critically affect the sorting behaviors of particles. Leukocyte sorting and monocyte purification directly from diluted blood samples have been demonstrated as biomedical applications. The presented system for particle/cell sorting would become a simple but versatile unit operation in microfluidic apparatus for chemical/biological experiments and manipulations.

Affinity-Bead-Mediated Enrichment of CD8+ Lymphocytes from Peripheral Blood Progenitor Cell Products Using Acoustophoresis

Acoustophoresis is a technique that applies ultrasonic standing wave forces in a microchannel to sort cells depending on their physical properties in relation to the surrounding media. Cell handling and separation for research and clinical applications aims to efficiently separate specific cell populations. Here, we investigated the sorting of CD8 lymphocytes from peripheral blood progenitor cell (PBPC) products by affinity-bead-mediated acoustophoresis. PBPC samples were obtained from healthy donors (n = 4) and patients (n = 18). Mononuclear cells were labeled with anti-CD8-coated magnetic beads and sorted on an acoustophoretic microfluidic device and by standard magnetic cell sorting as a reference method. CD8 lymphocytes were acoustically sorted with a mean purity of 91% ± 8% and a median separation efficiency of 63% (range 15.1%⁻90.5%) as compared to magnetic sorting (purity 91% ± 14%, recovery 29% (range 5.1%⁻47.3%)). The viability as well as the proliferation capacity of sorted lymphocytes in the target fraction were unimpaired and, furthermore, hematopoietic progenitor cell assay revealed a preserved clonogenic capacity post-sorting. Bead-mediated acoustophoresis can, therefore, be utilized to efficiently sort less frequent CD8+ lymphocytes from PBPC products in a continuous flow mode while maintaining cell viability and functional capacity of both target and non-target fractions.

Acousto-microfluidics for screening of ssDNA aptamer

We demonstrate a new screening method for obtaining a prostate-specific antigen (PSA) binding aptamer based on an acoustofluidic separation (acoustophoreis) technique. Since acoustophoresis provides simultaneous washing and separation in a continuous flow mode, we efficiently obtained a PSA binding aptamer that shows high affinity without any additional washing step, which is necessary in other screening methods. In addition, next-generation sequencing (NGS) was applied to accelerate the identification of the screened ssDNA pool, improving the selecting process of the aptamer candidate based on the frequency ranking of the sequences. After the 8^th round of the acoustophoretic systematic evolution of ligands by exponential enrichment (SELEX) and following sequence analysis with NGS, 7 PSA binding ssDNA aptamer-candidates were obtained and characterized with surface plasmon resonance (SPR) for affinity and specificity. As a result of the new SELEX method with PSA as the model target protein, the best PSA binding aptamer showed specific binding to PSA with a dissociation constant (K_d) of 0.7 nM.

Spatiotemporally controllable acoustothermal heating and its application to disposable thermochromic displays

Disposable thermochromic displays using spatiotemporally controllable acoustothermal heating are reported. A variety of thermochromic displays are presented to prove the applicability of the proposed thermochromic display system.

Acoustofluidic, label-free separation and simultaneous concentration of rare tumor cells from white blood cells

Enrichment of rare cells from peripheral blood has emerged as a means to enable noninvasive diagnostics and development of personalized drugs, commonly associated with a prerequisite to concentrate the enriched rare cell population prior to molecular analysis or culture. However, common concentration by centrifugation has important limitations when processing low cell numbers. Here, we report on an integrated acoustophoresis-based rare cell enrichment system combined with integrated concentration. Polystyrene 7 μm microparticles could be separated from 5 μm particles with a recovery of 99.3 ± 0.3% at a contamination of 0.1 ± 0.03%, with an overall 25.7 ± 1.7-fold concentration of the recovered 7 μm particles. At a flow rate of 100 μL/min, breast cancer cells (MCF7) spiked into red blood cell-lysed human blood were separated with an efficiency of 91.8 ± 1.0% with a contamination of 0.6 ± 0.1% from white blood cells with a 23.8 ± 1.3-fold concentration of cancer cells. The recovery of prostate cancer cells (DU145) spiked into whole blood was 84.1 ± 2.1% with 0.2 ± 0.04% contamination of white blood cells with a 9.6 ± 0.4-fold concentration of cancer cells. This simultaneous on-chip separation and concentration shows feasibility of future acoustofluidic systems for rapid label-free enrichment and molecular characterization of circulating tumor cells using peripheral venous blood in clinical practice.