Highly sensitive and compact microforce sensors with piconewton-level resolution are essential in various fields. However, these sensors face the challenge of delicate fabrication, expensive instruments, and complicated signal processing. Here, we report an ultrasensitive microforce sensor with a nanonewton-scale working range and piconewton-level resolution (picobalance) using a 500 nm diameter U-shaped silica optical nanofiber (ONF) as the cantilever beam and a gold microflake as the sample tray. The ONF can detect its deflection upon microforce by monitoring the change of its transmittance, making it a self-detection picobalance with a linear response to microforce in the range of 0–11.2 nN based on theoretical calculation. Benefiting from the extremely low spring constant of the ONF (e.g., 0.15 mN/m), the picobalance achieves a force resolution of 3.3 pN in an experiment measuring the radiation pressure. As proof-of-concept demonstrations, measuring nanogram-level microparticles and radiation pressure are realized. We believe that this easy-to-use picobalance has great potential for biological sensing, biomechanical research, and environmental monitoring.

中文翻译：

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光学纳米纤维自检测皮克天平


具有皮牛顿级分辨率的高灵敏度、紧凑型微力传感器在各个领域都是必不可少的。然而，这些传感器面临着精细制造、昂贵仪器和复杂信号处理的挑战。在这里，我们报告了一种超灵敏微力传感器，具有纳牛顿级工作范围和皮牛顿级分辨率（皮平衡），使用直径 500 nm 的 U 形二氧化硅光学纳米纤维（ONF）作为悬臂梁，金微米薄片作为样品托盘。 ONF可以通过监测其透过率的变化来检测其在微力作用下的偏转，根据理论计算，使其成为一种对微力在0-11.2 nN范围内具有线性响应的自检测皮克天平。得益于 ONF 极低的弹簧常数（例如 0.15 mN/m），皮克天平在测量辐射压力的实验中实现了 3.3 pN 的力分辨率。作为概念验证演示，实现了纳克级微粒和辐射压力的测量。我们相信这种易于使用的微微平衡在生物传感、生物力学研究和环境监测方面具有巨大的潜力。