Droplet Lab Publications

Surface tension measurement with a smartphone using a pendant drop

H. Chena,1, Jesus L. Muros-Cobosa,b,1, Juan A Holgado Terrizab, A. Amerfazlia,*
1 Department of Mechanical Engineering, York University, Toronto, ON M3J 1P3, Canada
2 Department of Software Engineering, University of Granada, Granada, 18071 Spain
In this study, a novel powerful mobile surface tension instrument based on a smartphone (mobile-phone or handy) is developed. Axisymmetric drop shape analysis method was implemented on a smart-phone (mobile- phone) for surface or interfacial tension measurements. The novelty of this work is that we have been able to implement all the needed calculations on a smartphone, and used the smartphone hardware for image acqui- sition and display purposes. As such we have been able to create an instrument that is significantly more eco- nomical compared to current systems; also it is compact, and can be mobile for field work. It is shown that the accuracy of our method can be 0.001% with ideal synthetic drop profiles (750 synthetic droplets representing a wide range of surface tension values were used). The performance of this instrument was also compared with a high-end commercial surface tension measurement instrument. We used various liquids (from high to low surface tension), and show that our instrument and the developed methodology can provide surface tension measurements as precise and accurate as current commercial instruments. http://dx.doi.org/10.1016/j.colsurfa.2017.08.019

Contact angle measurement with a smartphone

H. Chen,1,a) Jesus L. Muros-Cobos,1,2a) and A. Amirefazli1,b)
1 Department of Mechanical Engineering, York University, Toronto, Ontario M3J 1P3, Canada
2Department of Software Engineering, University of Granada, Granada 18010 Spain
Review of Scientific Instruments 89, 35117 (2018)
In this study, a smartphone-based contact angle measurement instrument was developed. Compared with the traditional measurement instruments, this instrument has the advantage of simplicity, com- pact size, and portability. An automatic contact point detection algorithm was developed to allow the instrument to correctly detect the drop contact points. Two different contact angle calculation methods, Young-Laplace and polynomial fitting methods, were implemented in this instrument. The performance of this instrument was tested first with ideal synthetic drop profiles. It was shown that the accuracy of the new system with ideal synthetic drop profiles can reach 0.01% with both Young- Laplace and polynomial fitting methods. Conducting experiments to measure both static and dynamic (advancing and receding) contact angles with the developed instrument, we found that the smartphone- based instrument can provide accurate and practical measurement results as the traditional commercial instruments. The successful demonstration of use of a smartphone (mobile phone) to conduct contact angle measurement is a significant advancement in the field as it breaks the dominate mold of use of a computer and a bench bound setup for such systems since their appearance in 1980s. Published by AIP Publishing. https://doi.org/10.1063/1.5022370