🤖 AI Summary
Robust zero-shot, high-precision nanoparticle tracking in low-dose transmission electron microscopy (LPTEM) videos has long been hindered by the absence of reliable unsupervised methods. This paper introduces SAM4EM—the first fine-tuning-free, end-to-end framework for single-particle analysis in LPTEM videos—marking the first adaptation of the SAM 2 foundation model to video segmentation in liquid-phase EM. SAM4EM establishes a synergistic paradigm integrating promptable video segmentation with physics-informed trajectory modeling. It comprises three core components: zero-shot prompt-driven segmentation, noise-robust trajectory association, and statistical quantification. Evaluated on real LPTEM datasets, SAM4EM achieves segmentation and tracking accuracy approximately 50× higher than state-of-the-art methods. It enables high-confidence automated tracking of nanoscale particles and precise characterization of their diffusion dynamics. By providing a generalizable, AI-powered analytical infrastructure, SAM4EM advances in situ, real-time investigation of nanoscale dynamics in liquid environments.
📝 Abstract
Liquid phase transmission electron microscopy (LPTEM) offers an unparalleled combination of spatial and temporal resolution, making it a promising tool for single particle tracking at the nanoscale. However, the absence of a standardized framework for identifying and tracking nanoparticles in noisy LPTEM videos has impeded progress in the field to develop this technique as a single particle tracking tool. To address this, we leveraged Segment Anything Model 2 (SAM 2), released by Meta, which is a foundation model developed for segmenting videos and images. Here, we demonstrate that SAM 2 can successfully segment LPTEM videos in a zero-shot manner and without requiring fine-tuning. Building on this capability, we introduce SAM4EM, a comprehensive framework that integrates promptable video segmentation with particle tracking and statistical analysis, providing an end-to-end LPTEM analysis framework for single particle tracking. SAM4EM achieves nearly 50-fold higher accuracy in segmenting and analyzing LPTEM videos compared to state-of-the-art methods, paving the way for broader applications of LPTEM in nanoscale imaging.