In situ detection, isolation, and enrichment of deep-sea microorganisms are pivotal for advancing deep-sea scientific research, particularly in the study of low-abundance microbial communities. This study developed an acoustically driven microfluidic fluorescence-activated cell sorting (mu FACS) device. Its dry-wet separation architecture enables unattended, automated in situ collection, detection, and enrichment of deep-sea microorganisms. The system employs ultrasonic standing waves (USSW) to achieve sheathless three-dimensional (3-D) focusing of microbial cells, coupled with laser-based detection of scattering/fluorescence signals for real-time identification and sorting. After optimizing staining protocols, high-efficiency in situ pretreatment was achieved at 4 degrees C, delivering sorting purities of 48.23 % and 85.27 % at microbial abundances of 9.43 % and 27.40 %, respectively, with a collection rate of approximately 50 %. Hydrostatic pressure test (20 MPa) and in-situ sea trials (1,350-meter depth) confirmed the engineering feasibility and environmental adaptability of mu FACS for deep-sea in situ detection and sorting, demonstrating a 4.93-fold increase in microbial abundance. This technology provides a novel tool for investigating deep-sea microbial distribution, enabling continuous in situ enrichment and high-purity sample acquisition, thereby promising to significantly enhance understanding of deep-sea ecosystems.

Raman spectroscopy is a non-destructive spectral analysis technique that obtains molecular structure information of Jubstances by analyzing the frequency changes of scattered light. Baseline correction is a key step in enhancing spectral data quality, as it removes background signals and unrelated noise to highlight and purify the target signal. Traditional Rarmar pectroscopy applications do not require high timeliness for baseline correction. Still, in recent years, applications such as flow Raman and endoscopic Raman. which require real-time processing of spectral data, have increased, placing higher demands on the speed and accuracy of baseline correction. Traditional methods, such as iterative polynomial fitting and wavelet transform bave time, accuracy, or adaptability deficiencies. This study developed a fast adaptive baseline correction algorithm based on the Minus Weighted Iterative Adjustment Least Square Method (MWIALS). The main principle is to extract the set of negative Values and assign them higher weights, continuously adjust the baseline during the iteration process, and set parameter thresholds to exit the loop to achieve fast and accurate baseline correction, We also proposed two parameter selection strategi Fixed Parameter (FMWIALS), suitable for rapid processing of batch homogeneous spectra, and Adaptive Parameter AMWIALS), suitable for adaptive processing of heterogeneous spectra. The algorithm was applied to flow Raman spectra Analysis of particulate matter, and the results showed that compared to other mainstream algorithms, it was significantly more efficient in practical spectral processing (average time of 47 milliseconds per spectrum) and achieved higher accuracy and adaptability. This algorithm can meet the real-time spectral processing needs in biological sample detection for flow Raman and Indoscopic Raman applications, providing strong support for the further application of Raman spectroscopy technology.

Rheumatoid arthritis (RA) is a common chronic inflammatory disease capable of causing the disability. Although various antioxidant strategies have been attempted for prevention and treatment of RA through scavenging the free radicals, the therapeutic effect is limited. Recently, it is reported that the unremitting course of RA intensely correlates with the persistence of immunologic memory, in which the imbalance of T helper 17 (Th17) cells/regulatory T (Treg) cells plays an important role. Herein, we constructed Janus mesenchymal stem cell (MSC)-hitchhiked melanin nanoparticles (MSCFM) for RA therapy, where one half of MSC kept intact for chemotactically migrating towards the RA inflammatory sites and efficiently restoring the Th17/Treg balance based on the property of MSCs, while the other half hitchhiked the iron-doped melanin (FM) nanoparticles (NPs) and release them to scavenge free radicals for maintaining the durability of Th17/Treg balance. In vitro studies indicated MSCFM could migrate towards CXCL12 inflammatory cytokine, scavenge reactive oxygen and nitrogen species, inhibit Th17 cell proliferation and induce Treg cell production. Further in vivo studies corroborated that intravenously injected MSCFM could target the RA site of collagen-induced arthritis mouse model and alleviate the pathological progression of RA. MSCFM holds great potential as an anti-inflammatory agent for RA management.

A highly efficient acoustic microfluidic trap that can offer low and large volume compatible ways of enriching sEVs from biological fluids has been reported.

Raman flow cytometry (RFC) uniquely integrates the “label-free” capability of Raman spectroscopy with the “high-throughput” attribute of traditional flow cytometry (FCM), offering exceptional performance in cell characterization and sorting. Unlike conventional FCM, RFC stands out for its elimination of the dependency on fluorescent labels, thereby reducing interference with the natural state of cells. Furthermore, it significantly enhances the detection information, providing a more comprehensive chemical fingerprint of cells. This review thoroughly discusses the fundamental principles and technological advantages of RFC and elaborates on its various applications in the biomedical field, from identifying and characterizing cancer cells for in vivo cancer detection and surveillance to sorting stem cells, paving the way for cell therapy, and identifying metabolic products of microbial cells, enabling the differentiation of microbial subgroups. Moreover, we delve into the current challenges and future directions regarding the improvement in sensitivity and throughput. This holds significant implications for the field of cell analysis, especially for the advancement of metabolomics.

Skin wounds, especially large-area skin trauma, would bring great pain and even fatal risk to patients. In recent years, local autologous cell transplantation has shown great potential for wound healing and re-epithelialization. However, when the cell suspension prepared with normal saline is delivered to the wound, due to its low viscosity, it is easy to form big drops in the deposition and lose them from the wound bed, resulting in cell loss and uneven coverage. Here, we developed a novel air-assisted atomization device (AAAD). Under proper atomization parameters, 1% (w/v) sodium alginate (SA) solution carrier could be sprayed uniformly. Compared with normal saline, the run-off of the SA on the surface of porcine skin was greatly reduced. In theory, the spray height of AAAD could be set to achieve the adjustment of a large spray area of 1-12 cm2. In the measurement of droplet velocity and HaCaT cell viability, the spray height of AAAD would affect the droplet settling velocity and then the cell delivery survival rate (CSR). Compared with the spray height of 50 mm, the CSR of 100 mm was significantly higher and could reach 91.09% ± 1.82% (92.82% ± 2.15% in control). For bio-ink prepared with 1% (w/v) SA, the viability remained the same during the 72-h incubation. Overall, the novel AAAD uniformly atomized bio-ink with high viscosity and maintained the viability and proliferation rate during the delivery of living cells. Therefore, AAAD has great potential in cell transplantation therapy, especially for large-area or irregular skin wounds.

In droplet-on-demand flow cell sorter where a single cell is encapsulated in a single droplet as designed, complex physical interactions govern the droplet characteristics, such as position, size, and shape. These droplet characteristics, in turn, determine the functional performance of expected cell sorting. Hence, to ensure repeatable and reliable cell sorting, it is necessary to monitor and control the droplet characteristics. The existing methods based on high-speed photography only obtain droplet features through simple image processing, which limits their robustness. And the existing droplet quality control strategies only focus on the overall instrument system, lacking direct and intuitive monitoring methods for the droplet itself. To overcome this challenge, the objective of this work is to build a visual monitoring method that can effectively evaluate the stability of droplet generation before flow cytometry sorting experiments. Specifically, we introduced a deep semantic segmentation model to segment each droplet image, then extracted 5 features that characterize droplet stability and calculate equivalent feature, and drew a quality control curve based on the statistical values of equivalent feature. Finally, based on the quality control curve, we determine whether the quality of droplet generation was controlled. The experiment showed that the droplet segmentation model achieved a segmentation accuracy of 99.32% and a prediction speed of 123.35ms per image on CPU. A demonstration application of the quality control approach was provided through case studies. Thus, this work achieves a practically visual monitoring approach to droplet stability generation for flow cell sorter in a simple and convenient way, with direct monitoring of droplet generation quality before flow cytometry experiment.

We report a simple and compact microchip capable of stable 3D trapping of single and multiple microparticles in the flowing liquid. The chip is constructed by attaching a piezoelectric plate transducer to a silicon-glass bonding plate with circular cavity. The cavity works as a resonant unit, excited at frequency of both half wave resonance in main plane and inverted quarter wave resonance in depth direction. The chip can provide nN level trapping force and ms level trapping time for micron sized particles moving at velocity of mm/s level. The time consumption of 3 mu m polystyrene particles trapping under 15Vpp driving amplitude is 103 ms. Red blood cells cluster can be trapped at flow rate of 32 mu L/min which corresponds to flow velocity of 60 mm/s. This circular cavity resonance based acoustic trap is simple, low cost, biocompatible, and with its high throughput trapping ability, which may be of interest for applications such as Reman analysis and seed particle-enabled nanoparticles enrichment.

Cell enrichment is a powerful tool in many kinds of cell research, especially in applications with low abundance cell types. In this work, we developed a microfluidic fluorescence activated cell sorting device that was able to perform on-demand, low loss cell detection, and sorting. The chip utilizes three-dimensional acoustic standing waves to position all cells in the same fluid velocity regime without sheath. When the cells pass through a laser interrogation region, the scattering and fluorescent signals are detected, translated and transported to software. The target cells are then identified by gating on the plots. Short bursts of standing acoustic waves are triggered by order from PC to sort target cells within predefined gating region. For very low abundance and rare labeled lymphocytes mixed with high concentration unlabeled white blood cells (WBCs), (1-100 labeled lymphocytes are diluted in 10(6) WBCs in 1 ml volume fluid), the device is able to remove more than 98% WBCs and recover labeled lymphocytes with efficiency of 80%. We further demonstrated that this device worked with real clinical samples by successfully isolating fetal nucleated red blood cells (FNRBCs) in the blood samples from pregnant women with male fetus. The obtained cells were sequenced and the expressions of (sex determining region Y) SRY genes were tested to determine fetal cell proportion. In genetic analysis, the proportion of fetal cells in the final picked sample is up to 40.64%. With this ability, the device proposed could be valuable for biomedical applications involving fetal cells, circulating tumor cells, and stem cells.

A compact driver based on current feedback amplifiers is designed to drive interdigital transducers (IDTs) that generate standing surface acoustic waves for cell sorting. Compared with commercial RF amplifiers, this driver can be used to drive a wider range of loads without impedance matching. Furthermore, the driver works in a switch mode triggered by target cells, which significantly reduces power consumption in the system. A Butterworth-Van Dyke equivalent circuit was fabricated to study the electrical characteristics of the IDTs, and the driver was designed and optimized by circuit simulations. A cell sorter was constructed and tested experimentally to demonstrate that the driver meets sorting requirements. The driver allows the cell sorter to extract rare cells while otherwise consuming low power.

In recent years, microflow cytometry has become a popular research field because of its potential to provide low-cost and disposable chips for complex cell analyses. Herein, we demonstrate a sheathless microflow cytometer which integrates a bulk standing acoustic wave based microchip capable of three dimensional cell focusing. Flow cytometry was successfully demonstrated using this system with a coefficient of variation (CV) of 2.16% with standard calibration beads. The sensitivities calibrated by rainbow beads are 518 MEFL in fluorescein Isothiocyanate (FITC) channel and 264 MEPE in P-phycoerythrin (PE) channels, respectively. The linearities are more than 99% in both channels. The capability of the proposed microflow cytometer is further demonstrated by immunologically labeled leukocytes differentiation in blood. This acoustic-based microflow cytometer did not require any sheath flows or complex structures and can be mass produced. Because of the simple fluid channel, the chip can be easily made pipeless, disposable for applications requiring no cross contamination. Moreover, with the gentle and bio-compatible acoustic waves used, this technique is expected to maintain the viability of cells and other bioparticles.

微流控芯片应用于细胞分析分选、微生物检测时,在流动区域中可能会形成驻点,驻点的存在可能会引起流道拥堵、样品污染、纯度下降等问题.针对该问题,设计了一种微流控芯片,利用逆流鞘液避免细胞在驻点区域接触壁面,从而防止细胞聚集阻塞流道,同时对分选通道和废液通道中样品流再次聚焦,使样品流动更加稳定.利用Fluent软件对这种微流控芯片中的流场进行仿真分析,得到其流动状态,验证了引入逆流鞘液对于避免驻点引起的阻塞问题具有一定作用,对设计应用于细胞分析分选的微流控芯片具有参考价值.

The current microfluidic chip design generally forms a stagnation point in the exit flow area of the microfluidic chip. The presence of the stagnation area can cause problems such as choke of channel and sample purity degradation. For this problem, a microfluidic chip with converse fluid was designed. The converse sheath liquid can avoid the adverse effects caused by the presence of the stagnation point. It can prevent the cells from contacting the wall surface, and avoid the blocking problem of cell. At the same time, the introduction of the converse sheath liquid can also focus the sample flow in the sorting channel and the waste channel again, which is convenient for the detection of the sorted sample. The fluid flow state in this microfluidic chip was also simulated, and it verified the benefit of introducing converse sheath fluid, which has reference value for the design of microfluidic chip for cell analysis and sorting.

Trapezoidal structure has been proposed for construction of piezoelectric cantilever to increase inherent frequency. To further break through the limitation on frequency value, trapezoidal piezoelectric cantilever is rolled into spiral-shaped piezoelectric cantilever with identical effective length in this study, which is verified in COMSOL simulations and experiments. A prototype shows that after rolling the straight shape into a spiral shape for the trapezoidal piezoelectric cantilever, the first inherent frequency promotes 4.5 times from 98100 Hz to 441,900 Hz, which is consistent with theoretic analysis. The spiral-shaped trapezoidal piezoelectric cantilever is suitable for working as an actuator in micro flapping-wing aircraft.

A piezoelectric motor that imitates the motion of a hula hoop was developed. It has the advantage of low sliding wear as static friction force is used to drive the rotor. The rotation speed of the rotor can be regulated by changing the exciting frequency of piezoelectric transducers. The stator is composed of four piezoelectric plates attached to a steel rod. Two orthogonal bending modes were excited by driving two pairs of piezoelectric plates, and circular motion was formed on the rod. The reversed motion of the rotor can be obtained by adjusting the phase of two bending modes. The prototype stator working at 39.1 Hz produced a rotation speed of 1142 rpm and a torque of 0.23 mN m.

为提高流式细胞仪的探测分辨率和数据检测的稳定性,需要精确控制样品流速,并分析样品流速和鞘液流速对样品聚焦流的影响,可通过样品聚焦流直径和样品聚焦流在流动室流道中的相对位置来评价样品的聚焦状况.利用蠕动泵运动特点,设计了一种平均流量称重法测量样品流速的方法,并与微流量传感器测量结果作比较;采用最小二乘法线性拟合蠕动泵的控制电压和样品流速之间的函数关系,并采用显微成像法直接测量和分析样品流速和鞘液流速对样品聚焦流直径、偏离流动室流道中心线的距离的影响.实验结果显示,采用平均流量称重法与微流量传感器测得的样品流速的线性相关系数高达0.9828;蠕动泵的样品流速与其控制电压的线性相关系数高于0.99,说明利用该线性关系可以实现样品流速的精确控制;采用的显微成像法能快速方便地测得样品聚焦流的直径及位置,为流式细胞仪样品流速、鞘液流速的调控以及液流器件组装精度的测试提供了指导方法.

Piezoelectric cantilever is suitable as an actuator for micro-flapping-wing aircraft. Higher resonant frequency brings about stronger flight energy, and the flight amplitude can be compensated by displacement–amplification mechanism, such as lever. To obtain a higher resonant frequency, straight piezoelectric bimorph was rolled into spiral-shaped piezoelectric bimorph with identical effective length in this study, which is verified in COMSOL simulations. Simulation results show that compared with the straight piezoelectric bimorph, the spiral-shaped piezoelectric bimorph with two turns has higher inherent frequencies (from 204.79 Hz to 504.84 Hz in terms of axial oscillation mode, and from 319.77 Hz to 704.48 Hz in terms of tangential torsional mode). The spiral-shaped piezoelectric bimorph is fabricated by a precise laser cutting process and consists of two turns with effective length of 60 mm, width of 2.5 mm, and thickness of 1.6 mm, respectively. With the excitation voltage of 100 Vpp applying an electric field across the thickness of the bimorph, the tip displacement of the actuator in the axial oscillation and tangential torsional modes are 85 [Formula: see text]m and 15 [Formula: see text]m, respectively.

A piezoelectric centrifugal pump was developed previously to overcome the low frequency responses of piezoelectric pumps with check valves and liquid reflux of conventional valveless piezoelectric pumps. However, the electro-mechanical-fluidic analysis on this pump has not been done. Therefore, multi-field analysis and experimental verification on piezoelectrically actuated centrifugal valveless pumps are conducted for liquid transport applications. The valveless pump consists of two piezoelectric sheets and a metal tube with piezoelectric elements pushing the metal tube to swing at the first bending resonant frequency. The centrifugal force generated by the swinging motion will force the liquid out of the metal tube. The governing equations for the solid and fluid domains are established, and the coupling relations of the mechanical, electrical and fluid fields are described. The bending resonant frequency and bending mode in solid domain are discussed, and the liquid flow rate, velocity profile, and gauge pressure are investigated in fluid domain. The working frequency and flow rate concerning different components sizes are analyzed and verified through experiments to guide the pump design. A fabricated prototype with an outer diameter of 2.2 mm and a length of 80 mm produced the largest flow rate of 13.8 mL/min at backpressure of 0.8 kPa with driving voltage of 80 Vpp. By solving the electro-mechanical-fluidic coupling problem, the model developed can provide theoretical guidance on the optimization of centrifugal valveless pump characters.

A three-dimensional focusing microfluidic chip which can be fabricated with plane micro machining technology, was designed based on Dean vortices theory, and simulated by FLUENT.The changing process of the Dean vortex and the focusing process of the sample in the curved pipe were studied.The influence of sample flow rate, sheath flow rate on the focusing capability were discussed.The simulated result verified the function of the chip and provided a reference to the control of the three-dimensional focusing microfluidic chip.

High power density is an important target to achieve in the piezoelectric devices and it is primarily limited by internal losses in a piezoelectric material. There are three losses in piezoelectric materials: dielectric, elastic and piezoelectric losses. In this paper, a new equivalent circuit is proposed considering these three losses. First, a six-terminal equivalent circuit is derived based on the Mason's equivalent circuit. In order to verify the feasibility of the new circuit, four different external loads configurations which reflect intensive and extensive loss behaviors are explored and simulated. The resonance and antiresonance frequencies and their corresponding mechanical quality factors derived from the circuits are compared with the actual samples with the different loads and boundary conditions. The simulation results have the same trend as the experimental measurements. Equivalent circuits with only dielectric, elastic losses were simulated to verify the accuracy improvement of the new equivalent circuits. The voltage distribution of non-electrode sample is simulated with the proposed equivalent circuit and matches the experimental result on the actual sample. (C) 2017 Elsevier B.V. All rights reserved.