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 ± 510.0 attonewton. 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 1.8 fN Hz^–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.

精确的力测量对于探测生物事件和物理过程（从分子马达的运动到卡西米尔效应）以及引力波的检测至关重要。然而，尽管技术取得了广泛的发展，水溶液中弱力的三维纳米级测量仍然面临着重大挑战。依赖于光学捕获纳米探针的技术具有巨大的潜力，但也存在局限性，包括高捕获功率引起的探针加热、不可检测的散射信号和定位误差。在这里，我们报告了水溶液中长距离相互作用力的测量，最小检测力值为 108.2 ± 510.0 attonewton。为了实现这一目标，我们开发了一种超分辨光子力显微镜，该显微镜基于光学捕获的镧系元素掺杂纳米粒子与纳米级三维跟踪力传感相结合。该跟踪方法利用神经网络支持的超分辨率定位，其中力探针的位置是从光学像散修改的点扩散函数中提取的。我们实现了低至 1.8 fN Hz ^{–1/2 的}力灵敏度，接近纳米级热极限。我们通过实验测量作用于单个纳米粒子的电泳力以及单个纳米粒子上的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，并为检测长距离的亚飞牛顿力和单分子水平的生物力学力提供了新的机会。