Ultrasensitive and rapid detection of nano‐objects is crucial in both fundamental studies and practical applications. Optical sensors using evanescent fields in microcavities, plasmonic resonators, and nanofibers allow label‐free detection down to single molecules, but practical applications are severely hindered by long response time and device reproducibility. Here, an on‐chip dense waveguide sensor to monitor single unlabeled nanoparticles in a strong optical evanescent field is demonstrated. The spiral nanowaveguide design enables two orders of magnitude enhancement in sensing area compared to a straight waveguide, significantly improving the particle capture ability and shortening the target analysis time. In addition, the measurement noise is suppressed to a level of 10⁻⁴ in the transmitted power, pushing the detection limit of single particles down to the size of 100 nm. The waveguide sensor on the silicon‐on‐isolator platform can be fabricated reproducibly by the conventional semiconductor processing and compatible with surface functionalization chemistries and microfluidics, which could lead to widespread use for sensing in environmental monitoring and human health.

中文翻译：

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片上螺旋波导，用于超灵敏和快速检测纳米级物体

纳米物体的超灵敏和快速检测在基础研究和实际应用中都至关重要。在微腔，等离子共振器和纳米纤维中使用渐逝场的光学传感器允许无标签检测到单个分子，但是响应时间长和设备可重现性严重阻碍了实际应用。此处展示了一种片上密集波导传感器，该传感器可在强光渐逝场中监视单个未标记的纳米颗粒。与直线波导相比，螺旋纳米波导设计可使感测面积提高两个数量级，从而显着提高了粒子捕获能力并缩短了目标分析时间。另外，将测量噪声抑制到10 ^-4的水平。在发射功率中，将单个粒子的检测极限降低到100 nm。绝缘体上硅平台上的波导传感器可以通过常规的半导体工艺可重复制造，并且与表面功能化化学物质和微流体兼容，从而可以广泛用于环境监测和人体健康的传感。