High-Speed Multipass Coulter Counter with Ultrahigh Resolution
High-Speed Multipass Coulter Counter with Ultrahigh Resolution
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DOI：
10.1021/acsnano.5b05554
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发表时间：
2015-12-01
期刊：
影响因子：
17.1
通讯作者：
White, Henry S.
中科院分区：
文献类型：
--
作者：
Edwards, Martin A.;German, Sean R.;White, Henry S.
库尔特计数器通过使溶液中的颗粒穿过孔口并测量电阻脉冲（即位于孔口两侧的两个电极之间流动的离子电流的下降）来测量溶液中颗粒的尺寸。脉冲的幅度给出了颗粒尺寸的信息；然而，由于粒子的布朗运动，分辨率受到易位路径变化的限制。我们提出了一种简单但功能强大的改进型库尔特计数器，它使用可编程数据采集硬件在感测通过纳米移液管孔口的纳米颗粒的电阻脉冲后切换电压。切换电压会反转粒子上的驱动力的方向，并且当重复此检测切换循环时，我们可以使单个纳米粒子通过孔口数千次。通过每秒测量单个颗粒超过 100 次，我们可以快速确定每个颗粒的电阻脉冲分布，这使我们能够准确确定平均脉冲幅度，并比传统库尔特计数器显着提高尺寸分辨率。我们证明，单个聚苯乙烯纳米粒子可以来回穿梭并监测几分钟，从而精确确定相当于亚埃尺寸分辨率的平均阻断电流。
Coulter counters measure the size of particles in solution by passing them through an orifice and measuring a resistive pulse, i.e., a drop in the ionic current flowing between two electrodes placed on either side of the orifice. The magnitude of the pulse gives information on the size of the particle; however, resolution is limited by variability in the path of the translocation, due to the Brownian motion of the particle. We present a simple yet powerful modified Coulter counter that uses programmable data acquisition hardware to switch the voltage after sensing the resistive pulse of a nanoparticle passing through the orifice of a nanopipet. Switching the voltage reverses the direction of the driving force on the particle and, when this detect-switch cycle is repeated, allows us to pass an individual nanoparticle through the orifice thousands of times. By measuring individual particles more than 100 times per second we rapidly determine the distribution of the resistive pulses for each particle, which allows us to accurately determine the mean pulse amplitude and deliver considerably improved size resolution over a conventional Coulter counter. We show that single polystyrene nanoparticles can be shuttled back and forth and monitored for minutes, leading to a precisely determined mean blocking current equating to sub-angstrom size resolution.