Hyper-Sensitive Chirality Detection via Frequency-Domain Polarization Field Mapping (FDPFM) for Bio-Molecular Assay Acceleration

This paper introduces Frequency-Domain Polarization Field Mapping (FDPFM), a novel technique designed to overcome the sensitivity limitations of current chiral molecule detection methods. Chirality, or a molecule's "handedness," is critical in fields like drug development and diagnostics, as different mirror-image forms (enantiomers) can have vastly different biological effects. Traditional detection methods often struggle to identify trace amounts of chiral molecules in complex biological samples. The FDPFM system builds upon Polarization-Sensitive Optical Coherence Tomography (PS-OCT) but introduces a critical innovation: it transforms polarization state information into the frequency domain. Instead of analyzing the raw optical signal directly, the system uses a Fast Fourier Transform (FFT) to convert the time-varying Stokes parameters (which describe the light's full polarization state) into a spectral representation. This process effectively separates the subtle signal generated by chiral molecules—specifically related to circular polarization (S3)—from overwhelming background noise. The key to its enhanced performance is a custom-designed digital filter that selectively amplifies the specific frequencies corresponding to the chiral signal while actively suppressing noise. This is analogous to isolating and boosting a single instrument's sound from a full orchestra. Experimental validation demonstrated a remarkable 10-fold improvement in sensitivity compared to standard PS-OCT techniques. The system successfully achieved a limit of detection below 1 nM and accurately discriminated between different enantiomers with high specificity and reproducibility. In conclusion, FDPFM represents a transformative advancement in chiral sensing. By combining frequency-domain analysis with targeted signal amplification, it has significant implications for accelerating drug discovery, developing new diagnostic biomarkers, and enhancing environmental monitoring, positioning it as a powerful, commercially-ready technology.本文介绍了频域偏振场映射（Frequency-Domain Polarization Field Mapping, FDPFM）——一种旨在突破当前手性分子检测方法灵敏度瓶颈的新型技术。手性（Chirality），即分子的“手性偏向”，在药物研发与诊断学等领域至关重要：不同镜像异构体（enantiomers）往往会产生截然不同的生物学效应。传统检测方法往往难以在复杂生物样本中识别痕量手性分子。 FDPFM系统以偏振敏感光学相干断层扫描（Polarization-Sensitive Optical Coherence Tomography, PS-OCT）为基础，却带来了一项关键创新：将偏振态信息转换至频域。该系统并未直接分析原始光学信号，而是借助快速傅里叶变换（Fast Fourier Transform, FFT），将描述光线完整偏振态的时变斯托克斯参数（Stokes parameters）转换为光谱表征形式。这一过程可有效将手性分子产生的微弱信号——尤其是与圆偏振（S3）相关的信号——从极强的背景噪声中分离出来。 该系统性能提升的核心在于定制化设计的数字滤波器，可选择性放大与手性信号对应的特定频率，同时主动抑制噪声，这一过程类似于从完整的管弦乐团音效中分离并增强单一乐器的声音。 实验验证表明，相较于标准PS-OCT技术，该系统的灵敏度实现了显著的10倍提升，成功将检测限降至1纳摩尔（nM）以下，并以高特异性与重现性精准区分不同的镜像异构体。 综上，FDPFM代表了手性传感领域的变革性进展。通过将频域分析与靶向信号放大相结合，该技术在加速药物研发、开发新型诊断生物标志物以及强化环境监测等方面均具有重要意义，有望成为一款功能强大且已具备商业化落地条件的技术。