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Highlights • Microfluidic cell counter for rapid enumeration of residual white blood cells in leucodepleted blood products. • Integration of target cell enrichment and on-chip cell staining functionalities into the microfluidic cell counter. • Reliable cell counting over a dynamic range of 0.1–26.8 cells/μL at a high throughput of 400 μL/min. • High-throughput, sample preparation-free counting of residual white blood cells. Abstract A residual white blood cell (rWBC) count is the remaining concentration of WBCs in leucodepleted blood products, and is an important quality-assurance parameter for blood transfusion. Current cell-counting methods rely on a small test volume that can result in the inherent statistical error involved in counting rWBCs present at low concentrations or manual sample preparation that increases experimental workload. To address these critical challenges, we present a microfluidic rWBC counter that (i) rapidly enriches rWBCs to reduce a sample volume to be examined and thus enable high-throughput cell counting, and (ii) integrates an on-chip cell staining module that contains reagent-containing hydrogel patches and allows the controlled release of a staining reagent. With these novel features, we demonstrated high-throughput rWBC counting by achieving reliable cell counting over a dynamic range of 0.1–26.8 rWBCs/μL and processing a blood sample at a high throughput of 400 μL per minute. In addition, we successfully performed sample preparation-free counting of rWBCs by integrating the on-chip staining module into the rWBC counter, offering sample-in-answer-out capability. On the basis of the results, the rWBC counter represents a promising tool for the quality control of WBC depletion and improvement in the safety of blood transfusion. [ABSTRACT FROM AUTHOR]

Simple and institutionalized testing of circulating biomarkers is essential for rapid cancer diagnosis and prognosis. However, blood sample preparation typically requires time-consuming separation steps and bulky, costly equipment. Although microfluidic separators have been developed for rapid and simple blood separation, their fluidic accessories such as syringe pumps still need to be miniaturized at a lower price before translating the separators into clinical practice. Here, we present a motorized smart pipette as a portable, cost-effective, and controllable pumping tool that can generate stable and high-pressure conditions suitable for high-throughput microfluidic blood separators. The pumping technology is based on a miniature air pump and its feedback control using an open-source microcontroller board. We characterized the pumping performance (controllability and stability) of the proposed technology using a pressure divider and a bang-bang feedback control method in a range of flow rate (166.5–529.0 μL/min). Additionally, we demonstrated the clinical utility of the pumping technology by rapidly separating blood plasma from whole blood and successfully recovering cancer cell-derived exosomes spiked in blood. We achieved high-throughput (≈422.3 μL/min) and high-purity (≈99.8%) plasma separation without hemolysis, recovering ≈90.5% of cancer cell-derived exosomes spiked in blood. With the advantages of high usability and versatility, this method can potentially accelerate the widespread adoption and clinical translation of microfluidics-based liquid biopsy technologies. [ABSTRACT FROM AUTHOR]

Blood viscosity is an important rheological property that have a potential for the diagnosis and prognosis of hemorheological alterations; however, conventional viscometers typically rely on costly and sophisticated equipment for device operation and viscosity measurement that limits their use in resource-limited settings. We present a 3D-printed capillary circuit (3D-CC) technology that enables facile analysis of blood viscosity by hand-powered device operation and naked-eye readout. Parallel capillary networks serve as the fluidic comparators that allow direct comparison between the volumetric flow rates of a viscosity standard and a test fluid, while graduated fluidic chambers enable naked-eye readout of the volumetric signals. The 3D-CC platform was first characterized with Newtonian fluids in a relatively wide range of viscosities (4.8–71.2 cP) by simple operation, pulling and pushing the plunger of a syringe. The practical utility of the 3D-CC was then demonstrated by rapid, low-cost, portable analysis of whole blood under controlled shear-rate conditions (48.5–482.1 s −1 ). The proposed platform provides cost-effectiveness and simplicity of operation compared with conventional viscometers, making it suited for its widespread use in field-based applications. [ABSTRACT FROM AUTHOR]

• An open-source, handheld, wireless spectrometer was developed for field-portable, multi-spectral analysis. • The spectrometer was combined with a 3D-printed helical mixer. • In vitro hemolysis assay using the spectrometer for quantification and screening of hemolytic agents. • Degradation kinetics study of an organic pollutant catalyzed by gold nanoparticles. Translating spectrometers into a field-portable, open-source analytical device offers great potential for clinical and environmental applications. However, current spectrometers lack one or more of the following features that might be necessary for the next-generation spectrometer: open-source engineering, multi-spectral analysis, rapid mixing, and portable, wireless operation. We herein report a handheld spectrometer made from commercially available parts, including a spectrometer sensor and a microcontroller, thus facilitating development of an open-source bioengineering tool. In contrast to the stereotype of conventional spectrometers, this device is designed as a micropipette, which can not only precisely place a liquid sample onto the sensor, but also rapidly mix assay components for homogeneous biochemical reactions by simple pipetting. In addition to the fluidic functionality, the embedded electronics enables continuous, wireless, multi-spectral analysis. We demonstrate these unique capabilities by evaluating the hemolytic potential of a toxic agent for blood, and the degradation kinetics of an organic pollutant catalyzed by gold nanoparticles. Overall, the brand-new spectrometer represents a rapidly evolving, potentially transformative technology that can facilitate unrestricted use, distribution, reproduction, and modification by non-expert users, and further enable diverse usage, even for unanticipated applications. [ABSTRACT FROM AUTHOR]

Magnetic activated cell sorting is a well-established technology to sort target cells from heterogeneous cell populations based on their specific surface receptors. However, conventional bulk separators rely on irregular and dense ferromagnetic matrices that can cause variances in separation purity and recovery. Recent microfluidic separators typically use narrow and two-dimensional laminar flows that can lead to low separation throughput. Here, we present a magnetizable micropipette tip incorporating a ferromagnetic matrix of nickel meshes that have regular and rectangular micropores. The functional pipette tip can be transiently magnetized by permanent magnets, thereby enabling the efficient capture and release of target cells by simple pipetting. We performed parametric studies to investigate optimal separation protocols such as the number of mesh layers and pipetting repetitions. We then applied the functional pipette tip for separation of bacterial cells from whole blood, confirming that the separation quality is sufficient for downstream cell culture and analysis. The magnetizable pipette tip provides high-throughput separation, processing 1 mL of blood within 7 min, and high-recovery separation, recovering ≈90.5% of the bacterial cells spiked into blood. [ABSTRACT FROM AUTHOR]