A designed setup of low-priced in-house goniometer/tensiometer

In many educational institutes and industries, the contact angle and surface tension analysis are done to measure the quality of a solid surface and of a liquid. In order to determine these, the sessile and pendant droplet method are the most widely used metrics, which are conventionally obtained using commercial goniometer/tensiometer. In view of the growing concern regarding compact and inexpensive but accurate experimental devices, we have developed a low-priced inhouse goniometer/tensiometer. This device has the benefit of easiness, compactness, and movability over the conventional measurement instruments. In this study, we have used the commercial Drop image advanced as well as the Drop analysis plugin in ImageJ with high quality sharp edges images to compute static contact angle and surface tension values. Detailed procedure to measure them have been discussed in this work. To validate the apparatus, various water-based solutions have been considered. The surface tension values obtained using the apparatus are in good agreement with those reported in the literature. However, the apparatus needs to validate for highly wettable and volatile fluids. The efficacious manifestation of this device to determine the contact angle is a compelling improvement in the area as it disrupts the trendof a bench designated setup which is heavy, bulky and expensive and are not suitable for field work. The standard threaded syringe-based low-priced goniometer/tensiometer fabricated is affordable, being less than 40 USD or 3000 INR. Variety of water-based solutions like Millipore water, SDS solution at CMC * (8.1 mM), SDS solution at CMC/2, SDS solution at 2xCMC have been considered for validation and compared with surface tension values. Such a low-cost goniometer prototype can serve the technological needs of scientific research labs, in imparting practical learning about repeatability and highly beneficial for industrial applications.