The paper presents a method for building a low-cost tensiometer to measure the interfacial surface tension between liquid and air. The project is based on common and well-known devices (analytical balance, Arduino micro controller, DC motor) and manufacturing techniques (CAD, 3D printing), mostly available in scientific and industrial laboratories. For the control of proposed devices the user-friendly software with graphical user interface was prepared in an open-source widget toolkit Qt with the use of programming language C++. The source code of the software and CAD models for printing components that allow to the self-build of the described tensiometer, were provided. Finally, the proposed measuring device was used to determine the surface tension of two types of ethylene glycol based nanofluids containing silicon nitrides and multi-walled carbon nanotubes. It was presented that proposed device could be successfully used with complex systems like nanofluids, even in case that commercially available equipment fails.

本文提出了一种构建低成本张力计以测量液体和空气之间的界面张力的方法。该项目基于常见和著名的设备（分析天平，Arduino微控制器，直流电动机）和制造技术（CAD，3D打印），大多数在科学和工业实验室中都可以使用。为了控制所提议的设备，在带有图形化用户界面的用户友好型软件中使用了编程语言C ++在开源小部件工具包Qt中进行了准备。提供了用于打印组件的软件和CAD模型的源代码，这些组件允许自行构建所描述的张力计。最后，该建议的测量设备用于确定两种类型的包含氮化硅和多壁碳纳米管的乙二醇基纳米流体的表面张力。据介绍，即使在商用设备出现故障的情况下，所提出的设备也可以成功地与诸如纳米流体的复杂系统一起使用。