This study presents a systematic optimization of sharp-corner microstructures integrated into a "Christmastree" architecture to overcome diffusion-limited mass transport in low-Reynolds-number regimes, enabling rapid and homogeneous mixing within complex branching networks for high-throughput microfluidic gradient generators. Through a bidirectional co-simulation workflow between SolidWorks and COMSOL Multiphysics, we map the non-linear coupling between geometric parameters, i.e., the sharp-corner width and height, and the resulting mixing performance. Analysis of the global design space reveals a multi-peaked landscape, facilitating critical distinction between physically viable structural optima and numerical "pseudo-optima" plagued by deleterious flow separation and stagnant dead zones. The structural optimum is identified at a height of 0.16 mm and a width of 0.1 mm, where induced transverse secondary flows maximize concentration homogenization while preserving hydrodynamic integrity. This study provides a robust methodological reference for the automated design of passive microfluidic modules, ensuring reliable gradient generation for next-generation lab-on-a-chip applications.
Zijian Zhang, Wenfeng Liang, Hengchao Qu et al.· 2026 International Conferenc...· 0 citations
The mechanical properties of cells are critical indicators of cellular physiological state and function. However, existing technologies still face challenges in achieving non-contact, force-calibrated, and precisely controlled single-probe measurements of single-cell mechanical properties. A phase-programmable surface acoustic wave (SAW) platform is presented, in which orthogonally arranged interdigitated transducers (IDTs) generate controllable acoustic fields for deterministic two-dimensional manipulation of microspheres. Dynamic phase modulation of the SAW fields enables high-precision microsphere steering while producing tunable acoustic radiation forces in the piconewton-nanonewton range. To enable direct quantitative characterization of acoustic forces, a calibrated microneedle-microsphere force probe is integrated into the platform. This configuration establishes an experimental phase-force relationship, enabling in situ calibration of acoustic radiation forces without relying on theoretical models or indirect calculation. Based on this experimentally calibrated acoustic force framework, SAW-driven 5 μm microspheres are employed as localized single probes to perform controlled acoustic indentation of adherent C2C12 myoblasts. The apparent Young's modulus is determined to be 1.63 ± 0.21 kPa using Hertzian contact mechanics and shows agreement with AFM-based measurements under comparable experimental conditions. c Overall, this work establishes a calibrated acoustic radiation force measurement and single-cell apparent Young's modulus characterization approach. This approach may have potential significance for non-contact mechanophenotyping and lab-on-chip based cell mechanics studies. STATEMENT OF SIGNIFICANCE: R2: Accurate single-cell mechanical characterization is limited by the lack of direct force calibration and controllable acoustic loading in SAW-based techniques. In this work, we implemented a phase-programmable SAW platform that enables deterministic microsphere manipulation and controllable acoustic force generation. By integrating a calibrated microneedle-microsphere probe, we established a direct phase-force relationship, enabling in situ and direct measurement of acoustic radiation forces and overcoming reliance on theoretical or indirect force estimation. This calibrated acoustic manipulation framework further enables controlled probe-based indentation of adherent cells and quantitative determination of their apparent Young's modulus. The proposed work may advance acoustic force-based mechanophenotyping and provide a promising pathway toward scalable, chip-integrated single-cell mechanical analysis.
Hengchao Qu, Jialin Shi, Hongyu Wang et al.· Acta Biomaterialia· 0 citations
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