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By leveraging the benefits of a high energy density, miniaturization and integration, acoustic-wave-driven micromotors have recently emerged as powerful tools for microfluidic actuation. In this study, a Lamb-wave-driven micromotor is proposed for the first time. This motor consists of a ring-shaped Lamb wave actuator array with a rotor and a fluid coupling layer in between. On a driving mechanism level, high-frequency Lamb waves of 380 MHz generate strong acoustic streaming effects over an extremely short distance; on a mechanical design level, each Lamb wave actuator incorporates a reflector on one side of the actuator, while an acoustic opening is incorporated on the other side to limit wave energy leakage; and on electrical design level, the electrodes placed on the two sides of the film enhance the capacitance in the vertical direction, which facilitates impedance matching within a smaller area. As a result, the Lamb-wave-driven solution features a much lower driving voltage and a smaller size compared with conventional surface acoustic-wave-driven solutions. For an improved motor performance, actuator array configurations, rotor sizes, and liquid coupling layer thicknesses are examined via simulations and experiments. The results show the micromotor with a rotor with a diameter of 5 mm can achieve a maximum angular velocity of 250 rpm with an input voltage of 6 V. The proposed micromotor is a new prototype for acoustic-wave-driven actuators and demonstrates potential for lab-on-a-chip applications.
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The µTAS/LOC, a highly integrated microsystem, consolidates multiple bioanalytical functions within a single chip, enhancing efficiency and precision in bioanalysis and biomedical operations. Microfluidic centrifugation, a key component of LOC devices, enables rapid capture and enrichment of tiny objects in samples, improving sensitivity and accuracy of detection and diagnosis. However, microfluidic systems face challenges due to viscosity dominance and difficulty in vortex formation. Acoustic-based centrifugation, particularly those using surface acoustic waves (SAWs), have shown promise in applications such as particle concentration, separation, and droplet mixing. However, challenges include accurate droplet placement, energy loss from off-axis positioning, and limited energy transfer from low-frequency SAW resonators, restricting centrifugal speed and sample volume. In this work, we introduce a novel ring array composed of eight Lamb wave resonators (LWRs), forming an Ultra-Fast Centrifuge Tunnel (UFCT) in a microfluidic system. The UFCT eliminates secondary vortices, concentrating energy in the main vortex and maximizing acoustic-to-streaming energy conversion. It enables ultra-fast centrifugation with a larger liquid capacity (50 µL), reduced power usage (50 mW) that is one order of magnitude smaller than existing devices, and greater linear speed (62 mm/s), surpassing the limitations of prior methods. We demonstrate successful high-fold enrichment of 2 µm and 10 µm particles and explore the UFCT's potential in tissue engineering by encapsulating cells in a hydrogel-based micro-organ with a ring structure, which is of great significance for building more complex manipulation platforms for particles and cells in a bio-compatible and contactless manner.
Asunto(s)
Centrifugación , Humanos , Dispositivos Laboratorio en un Chip , Técnicas Analíticas Microfluídicas , AcústicaRESUMEN
Particles, ranging from submicron to nanometer scale, can be broadly categorized into biological and non-biological types. Submicron-to-nanoscale bioparticles include various bacteria, viruses, liposomes, and exosomes. Non-biological particles cover various inorganic, metallic, and carbon-based particles. The effective manipulation of these submicron to nanoparticles, including their separation, sorting, enrichment, assembly, trapping, and transport, is a fundamental requirement for different applications. Acoustofluidics, owing to their distinct advantages, have emerged as a potent tool for nanoparticle manipulation over the past decade. Although recent literature reviews have encapsulated the evolution of acoustofluidic technology, there is a paucity of reports specifically addressing the acoustical manipulation of submicron to nanoparticles. This article endeavors to provide a comprehensive study of this topic, delving into the principles, apparatus, and merits of acoustofluidic manipulation of submicron to nanoparticles, and discussing the state-of-the-art developments in this technology. The discourse commences with an introduction to the fundamental theory of acoustofluidic control and the forces involved in nanoparticle manipulation. Subsequently, the working mechanism of acoustofluidic manipulation of submicron to nanoparticles is dissected into two parts, dominated by the acoustic wave field and the acoustic streaming field. A critical analysis of the advantages and limitations of different acoustofluidic platforms in nanoparticles control is presented. The article concludes with a summary of the challenges acoustofluidics face in the realm of nanoparticle manipulation and analysis, and a forecast of future development prospects.
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Liposomes have garnered significant attention owing to their favorable characteristics as promising carriers. Microfluidic based hydrodynamic flow focusing, or micro-mixing approaches enable precise control of liposome size during their synthesis due to the comparable size scale. However, current microfluidic approaches still have issues such as high flow rate dependency, complex chip structures, and ease of clogging. Herein, we present a novel microfluidic platform for size-tunable liposome synthesis based on an ultra-high-frequency acoustic resonator. By designing the shape and orientation of the acoustic resonator in the three-phase laminar flow, it combined the features of both hydrodynamic flow focusing and rapid micro-mixing. The distribution of lipid precursor solution in laminar flow and the mixing conditions could be regulated by the confined acoustic streaming vortex. We successfully synthesize liposomes with adjustable sizes and narrow size distributions. Notably, this platform regulates the product size by adjusting only the input power, which is less dependent on the flow rate. Furthermore, the vortex-like fluid flow generated along the device edge effectively prevents precipitation due to excessive lipid concentration or contact with the wall.
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OBJECTIVE: To investigate the effect of ALST (artificial liver support treatment) on inflammatory factors and prognosis in patients with ACLF (acute-on-chronic liver failure). METHODS: Data of ACLF patients admitted to the No. 2 People's Hospital of Lanzhou from June 2020 to January 2023 were retrospectively analyzed. Patients were compared before and after ALST in terms of ALT (Alanine Aminotransferase), AST (Aspartate Aminotransferase), TBil (Total Bilirubin), Cr (Creatinine), INR (International Normalized Ratio), MELD (Model for End-Stage Liver Disease) scores, as well as TNF-α (Tumor Necrosis Factor-α), IL-33 (Interleukin-33), and MIP-1α (Macrophage Inflammatory Protein-1 α) levels. The ROC (receiver operating characteristic) curve was used to analyze the efficacy of the above indicators in predicting 90-day mortality in patients. RESULTS: After the treatment, the levels of ALT, AST, TBil, Cr, INR, and MELD score were significantly lower than those before treatment (all P<0.001). Also, the levels of TNF-α, IL-33, and MIP-1α were substantially lower than those before treatment (all P<0.001). TNF-α, IL-33, and MIP-1α were positively correlated with MELD score before and after the treatment (all P<0.01). TNF-α, IL-33, MIP-1α, and MELD score were significantly higher in the death group than in the survival group (all P<0.01). The ROC curves showed that MELD (AUC=0.857), TNF-α (AUC=0.836), IL-33 (AUC=0.749), and MIP-1α (AUC=0.746) had high efficacy in predicting patients' 90-day mortality. CONCLUSION: ALST can significantly reduce TNF-α, IL-33, and MIP-1α levels in patients with ACLF, and postoperative TNF-α, IL-33, and MIP-1α levels have a high predictive value for patients' prognosis.