Unconventional Computing Laboratory, University of the West of England, Bristol, BS161QY, UK.
Lab Chip. 2020 Jan 7;20(1):136-146. doi: 10.1039/c9lc01001g. Epub 2019 Nov 28.
Liquid marbles (LMs) are of growing interest in many fields, including microfluidics, microreactors, sensors, and signal carriers. The generation of LMs is generally performed manually, although there has recently been a burst of publications involving 'automatic marble makers'. The characteristics of a LM is dependent on many things, including how it is generated, it is therefore important to be able to characterise LMs once made. Here is presented a novel contactless LM sensor, constructed on a PCB board with a comb-like structure of 36 interlacing electrical traces, 100 μm wide and 100 μm apart. This cheap, scalable, and easy to use sensor exploits the inherent impedance (comprised of the electrical resistance, capacitive reactance and inductive reactance) of different LMs. With it, parameters of a LM can be easily determined, without interfering with the LM. These parameters are (1) particle size of the LM coating, (2) the concentration of a NaCl solution used as the LM core, and (3) the volume of the LM. Additionally, due to the comb-like nature of the sensor, the accurate positioning (down to the inter-trace spacing) of the LM can be ascertained. The new sensor has been shown to work under both static and dynamic (mobile) conditions. The capacitance of a LM was recorded to be 0.10 pF, which compares well with the calculated value of 0.12 pF.
液态大理石（LMs）在许多领域都越来越受到关注，包括微流控、微反应器、传感器和信号载体。LMs 的生成通常是手动进行的，尽管最近有大量涉及“自动大理石生成器”的出版物。LMs 的特性取决于许多因素，包括其生成方式，因此，在生成后对其进行特性描述非常重要。这里提出了一种新型的非接触式 LMs 传感器，该传感器构建在具有梳状结构的 PCB 板上，该梳状结构由 36 个交错的电迹组成，宽度为 100μm，间距为 100μm。这种便宜、可扩展且易于使用的传感器利用了不同 LMs 的固有阻抗（包括电阻、电容电抗和电感电抗）。通过它，可以轻松确定 LMs 的参数，而不会干扰 LMs。这些参数是（1）LM 涂层的颗粒大小，（2）用作 LM 核心的 NaCl 溶液的浓度，和（3）LM 的体积。此外，由于传感器具有梳状结构，可以确定 LM 的精确位置（精确到迹线之间的间距）。该新型传感器已被证明在静态和动态（移动）条件下都能正常工作。记录到的 LM 的电容为 0.10pF，与计算值 0.12pF 非常吻合。
