Recently, electrical sensing techniques for single objects, such as nanoparticles, biomolecules, and viruses, have attracted a great deal of attention. To achieve both high throughput and high measurement accuracy, target objects need to be quickly transported to a small sensing section embedded in a fluidic channel. In the present study, we propose a novel method to improve the signal-to-noise (S/N) ratio of electrical signals of single particles, using optical tweezers and a microchannel. Optically trapping a 2 μm microparticle in a micro-orifice that has a comparable dimension of 3.0 μm (W), 2.5 μm (H), and 3.0 μm (L), the electrical signal from a small target particle that passes by the microparticle is sharpened and separated from the background noise. By irradiation with near-infrared light, the micro-orifice can be switched between opening and closing by optical tweezers, which works effectively to bring target particles to the sensing section using liquid flows and electrophoretic transport. As a result, the S/N ratio of electrical sensing of the smaller particle is improved by a factor of 5. The present microfluidic chip enables us to electrically detect particles of several hundreds of nanometers. Based on the present method, identification of single nanoparticles will also be feasible by using machine learning in the near future.

中文翻译：

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使用光镊的微纳米双峰单粒子传感

最近，针对单个物体（如纳米颗粒、生物分子和病毒）的电传感技术引起了极大的关注。为了同时实现高吞吐量和高测量精度，需要将目标对象快速传输到嵌入流体通道中的小型传感部分。在本研究中，我们提出了一种使用光镊和微通道提高单个粒子电信号信噪比 (S/N) 的新方法。在具有 3.0 μm (W)、2.5 μm (H) 和 3.0 μm (L) 相当尺寸的微孔中光学捕获 2 μm 微粒，通过微粒的小目标粒子的电信号为锐化并与背景噪声分离。通过近红外光照射，微孔可以通过光镊在打开和关闭之间切换，它可以有效地利用液体流动和电泳传输将目标粒子带到传感部分。结果，较小颗粒的电传感的信噪比提高了 5 倍。目前的微流控芯片使我们能够电检测数百纳米的颗粒。基于目前的方法，在不久的将来使用机器学习识别单个纳米颗粒也将是可行的。目前的微流控芯片使我们能够电检测数百纳米的粒子。基于目前的方法，在不久的将来使用机器学习识别单个纳米颗粒也将是可行的。目前的微流控芯片使我们能够电检测数百纳米的粒子。基于目前的方法，在不久的将来使用机器学习识别单个纳米颗粒也将是可行的。