We have developed a microfluidic needle-like device that can extract and deliver nanoliter samples. The device consists of a T-junction to form segmented flows, parallel channels to and from the needle tip, and seven hydrophilic capillaries at the tip that form a phase-extraction region. The main microchannel is hydrophobic and carries segmented flows of water-in-oil. The hydrophilic capillaries transport the aqueous phase with a nearly zero pressure gradient but require a pressure gradient of 19 kPa for mineral oil to invade and flow through. Using this device, we demonstrate the delivery of nanoliter droplets and demonstrate sampling through the formation of droplets at the tip of our device. During sampling, we recorded the fluorescence intensities of the droplets formed at the tip while varying the concentration of dye outside the tip. We measured a chemical signal response time of approximately 3 s. The linear relationship between the recorded fluorescence intensity of samples and the external dye co...

中文翻译：

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用于通过分段流采样和传递化学信号的微流体针

我们开发了一种微流体针状装置，可以提取和输送纳升样品。该装置包括一个 T 形接头以形成分段流、进出针尖的平行通道以及位于尖端的七个亲水毛细管，形成一个相提取区域。主微通道是疏水的，并携带油包水的分段流。亲水性毛细管以几乎为零的压力梯度输送水相，但需要 19 kPa 的压力梯度才能让矿物油侵入和流过。使用该设备，我们演示了纳升液滴的输送，并通过在我们的设备尖端形成液滴来演示采样。在采样过程中，我们记录了尖端形成的液滴的荧光强度，同时改变了尖端外染料的浓度。我们测量了大约 3 秒的化学信号响应时间。记录的样品荧光强度与外部染料的线性关系...