A microfluidic device using on-chip passive pumping was characterized for use as a particle counter. Flow occurred due to a Young-Laplace pressure gradient between two 1.2 mm diameter inlets and a 4 mm diameter reservoir when 0.5μ L fluid droplets were applied to the inlets using a micropipette. Polystyrene particles (10μm diameter) were enumerated using the resistive pulse technique. Particle counts using passive pumping were within 13% of counts from a device using syringe pumping. All pumping methods produced particle counts that were within 16% of those obtained with a hemocytometer. The effect of intermediate wash steps on particle counts within the passive pumping device was determined. Zero, one, or two wash droplets were loaded after the first of two sample droplets. No statistical difference was detected in the mean particle counts among the loading patterns (p > 0.05). Hydrodynamic focusing using passive pumping was also demonstrated.

中文翻译：

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微流体被动泵浦库尔特计数器。

使用片上被动泵浦的微流体装置被表征为用作粒子计数器。当使用微量移液管将 0.5μ L 液滴施加到入口时，由于两个 1.2 毫米直径入口和 4 毫米直径储液器之间的杨拉普拉斯压力梯度而发生流动。聚苯乙烯颗粒（10μm 直径）使用电阻脉冲技术进行计数。使用被动泵送的颗粒计数与使用注射器泵送的设备的计数相差在 13% 以内。所有泵送方法产生的颗粒计数与使用血细胞计数器获得的颗粒计数相差在 16% 以内。确定了中间洗涤步骤对被动泵送装置内颗粒计数的影响。在两个样品液滴中的第一个之后加载零、一个或两个洗涤液滴。在加载模式之间的平均颗粒计数中没有检测到统计学差异（p > 0.05）。还展示了使用被动泵浦的流体动力聚焦。