Liu Lelin, Hu Dinglong, Lam Raymond H W
Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China.
Institute of Biointelligence Technology, BGI-Shenzhen, Shenzhen 518083, China.
Micromachines (Basel). 2020 Oct 14;11(10):934. doi: 10.3390/mi11100934.
The viscosity of biofluids such as blood and saliva can reflect an individual's health conditions, and viscosity measurements are therefore considered in health monitoring and disease diagnosis. However, conventional viscometers can only handle a larger liquid volume beyond the quantity that can be extracted from a person. Though very effective, micro-sensors based on electrokinetic, ultrasonic, or other principles often have strict requirements for the supporting equipment and complicated procedures and signal processing. Sample contamination is always an important issue. In this paper, we report a microfluidic viscometer requiring a small volume of biosamples (<50 µL) and straightforward operation procedures. It is fabricated with low-cost and biocompatible polymeric materials as one-time-use devices, such that contamination is no longer the concern. It contains a suspending micromembrane located along a microchannel. Under a steady driving pressure, the membrane displacement is a function of viscosity of the liquid sample being tested. We derived a simple analytical relation and perform a simulation for converting the membrane displacement to the sample viscosity. We conducted experiments with liquids (water and mineral oil) with defined properties to verify such a relation. We further applied the micro-viscometer to measure bovine blood samples with different hematocrit levels. It can be concluded that the microfluidic viscometer has a high compatibility with a broad range of biomedical applications.
血液和唾液等生物流体的粘度可以反映个体的健康状况，因此粘度测量被用于健康监测和疾病诊断。然而，传统粘度计只能处理比从人体中提取的量更大的液体体积。基于电动、超声或其他原理的微传感器虽然非常有效，但通常对支撑设备有严格要求，且程序和信号处理复杂。样品污染始终是一个重要问题。在本文中，我们报道了一种微流控粘度计，它需要少量生物样品（<50µL）且操作程序简单。它由低成本且具有生物相容性的聚合物材料制成，作为一次性使用的设备，因此不再担心污染问题。它包含一个沿着微通道设置的悬浮微膜。在稳定的驱动压力下，膜的位移是被测液体样品粘度的函数。我们推导了一个简单的解析关系，并进行了模拟，以将膜的位移转换为样品粘度。我们用具有确定特性的液体（水和矿物油）进行了实验，以验证这种关系。我们进一步应用该微粘度计测量了不同血细胞比容水平的牛血样品。可以得出结论，该微流控粘度计与广泛的生物医学应用具有高度兼容性。
