近日，北京航空航天大学的常凌乾&王帆及其研究团队取得一项新进展。经过不懈努力，他们通过超分辨光子力显微镜实现溶液中的亚飞牛顿力传感。相关研究成果已于2024年6月14日在国际知名学术期刊《自然—光子学》上发表。

据悉，精确的力测量对于探测生物事件和物理过程至关重要，从分子运动到卡西米尔效应，以及引力波的探测。然而，尽管技术得到了广泛的发展，但水溶液中弱力的三维纳米尺度测量仍然面临着重大挑战。光捕获纳米探针技术虽具有巨大潜力，但也存在不容忽视的局限，如高捕获功率导致的探针过热、散射信号难以检测以及定位误差等问题。

本文报道了水溶液中长距离相互作用力的测量，成功实现的最小力值达到108.2±510.0牛顿。为实现这一高精度测量，研究人员开发了一种基于光学捕获镧系掺杂纳米粒子的超分辨光子力显微镜，并结合了纳米尺度三维跟踪的力传感技术。该技术利用神经网络支持的超分辨率定位方法，通过光学像散修正的点扩散函数精确提取力探头的位置。研究团队成功将力灵敏度提升至1.8fNHz^-1/2，接近纳米级热噪声极限。

研究人员通过实验测量了作用在单个纳米颗粒上的电泳力以及单个纳米颗粒上表面诱导的相互作用力。这项工作开辟了纳米级热限制力传感的途径，并为远距离探测亚飞牛顿力和单分子水平的生物力学力提供了新的机会。

附：英文原文

Title: Sub-femtonewton force sensing in solution by super-resolved photonic force microscopy

Author: Shan, Xuchen, Ding, Lei, Wang, Dajing, Wen, Shihui, Shi, Jinlong, Chen, Chaohao, Wang, Yang, Zhu, Hongyan, Huang, Zhaocun, Wang, Shen S. J., Zhong, Xiaolan, Liu, Baolei, Reece, Peter John, Ren, Wei, Hao, Weichang, Lu, Xunyu, Lu, Jie, Su, Qian Peter, Chang, Lingqian, Sun, Lingdong, Jin, Dayong, Jiang, Lei, Wang, Fan

Issue&Volume: 2024-06-14

Abstract: Precise force measurement is critical to probe biological events and physics processes, spanning from molecular motor’s motion to the Casimir effect, as well as the detection of gravitational waves. Yet, despite extensive technological developments, the three-dimensional nanoscale measurement of weak forces in aqueous solutions still faces major challenges. Techniques that rely on optically trapped nanoprobes are of significant potential but are beset with limitations, including probe heating induced by high trapping power, undetectable scattering signals and localization errors. Here we report the measurement of the long-distance interaction force in aqueous solutions with a minimum detected force value of 108.2±510.0attonewton. To achieve this, we develop a super-resolved photonic force microscope based on optically trapped lanthanide-doped nanoparticles coupled with nanoscale three-dimensional tracking-based force sensing. The tracking method leverages neural-network-empowered super-resolution localization, where the position of the force probe is extracted from the optical-astigmatism-modified point spread function. We achieve a force sensitivity down to 1.8fNHz^–1/2, which approaches the nanoscale thermal limit. We experimentally measure electrophoresis forces acting on single nanoparticles as well as the surface-induced interaction force on a single nanoparticle. This work opens the avenue of nanoscale thermally limited force sensing and offers new opportunities for detecting sub-femtonewton forces over long distances and biomechanical forces at the single-molecule level.

DOI: 10.1038/s41566-024-01462-7

Source: https://www.nature.com/articles/s41566-024-01462-7