Huang Zhengzhong, Wang Zhe, Pirone Daniele, Bianco Vittorio, Miccio Lisa, Memmolo Pasquale, Cao Liangcai, Ferraro Pietro
Institute of Applied Sciences and Intelligent Systems "E. Caianiello", Italian National Research Council (ISASI-CNR), Italy.
Department of Precision Instrument, Tsinghua University, Beijing 100084, China.
APL Bioeng. 2024 Sep 10;8(3):036114. doi: 10.1063/5.0222932. eCollection 2024 Sep.
Lab-on-a-Chip microfluidic devices present an innovative and cost-effective platform in the current trend of miniaturization and simplification of imaging flow cytometry; they are excellent candidates for high-throughput single-cell analysis. In such microfluidic platforms, cell tracking becomes a fundamental tool for investigating biophysical processes, from intracellular dynamics to the characterization of cell motility and migration. However, high-throughput and long-term cell tracking puts a high demand on the consumption of computing resources. Here, we propose a novel strategy to achieve rapid 3D cell localizations along the microfluidic channel. This method is based on the spatiotemporal manipulation of recorded holographic interference fringes, and it allows fast and precise localization of cells without performing complete holographic reconstruction. Conventional holographic tracking is typically based on the phase contrast obtained by decoupling the calculation of optical axial and transverse coordinates. Computing time and resource consumption may increase because all the frames need to be calculated in the Fourier domain. In our proposed method, the 2D transverse positions are directly located by morphological calculation based on the hologram. The complex-amplitude wavefronts are directly reconstructed by spatiotemporal phase shifting to calculate the axial position by the refocusing criterion. Only spatial calculation is considered in the proposed method. We demonstrate that the computational time of transverse tracking is only one-tenth of the conventional method, while the total computational time of the proposed method decreases up to 54% with respect to the conventional approach. The proposed approach can open the route for analyzing flow cytometry in quantitative phase microscopy assays.
芯片实验室微流控设备在当前成像流式细胞术小型化和简化的趋势中提供了一个创新且经济高效的平台；它们是高通量单细胞分析的理想选择。在这样的微流控平台中，细胞追踪成为研究生物物理过程的基本工具，从细胞内动态到细胞运动性和迁移的表征。然而，高通量和长期的细胞追踪对计算资源的消耗提出了很高的要求。在此，我们提出一种新颖的策略，以实现沿微流控通道的快速三维细胞定位。该方法基于对记录的全息干涉条纹的时空操纵，并且无需进行完整的全息重建就能快速精确地定位细胞。传统的全息追踪通常基于通过解耦光轴和横向坐标的计算而获得的相位对比度。由于所有帧都需要在傅里叶域中进行计算，计算时间和资源消耗可能会增加。在我们提出的方法中，二维横向位置通过基于全息图的形态学计算直接定位。通过时空相移直接重建复振幅波前，以根据重新聚焦准则计算轴向位置。所提出的方法仅考虑空间计算。我们证明横向追踪的计算时间仅为传统方法的十分之一，而所提出方法的总计算时间相对于传统方法减少了高达54%。所提出的方法可以为定量相显微镜分析中的流式细胞术分析开辟道路。
