{"id":83422,"key":"Contact_angle_with_cell_phone","title":"Contact angle with cell phone","latest":{"id":1206999,"timestamp":"2025-11-27T21:18:05Z"},"content_model":"wikitext","license":{"url":"https://www.appropedia.org/Appropedia:Copyrights","title":"CC-BY-SA-4.0"},"source":"[[File:CellphoneCA.PNG|thumb]]\n\n{{MOST}}\n\nThis page gives instructions on how to use your cell phone to take contact angle measurements.\n\n== Experimental Instructions ==\n\n# Put your sample on a flat substrate\n# Use a micropipette to deposit a small droplet of fluid on the sample\n# Take a picture of the droplet from the side of the substrate as shown in Figure below. Make sure the image is in focus and not blurry.\n\n== Software analysis ==\n\n# Install the open source imageJ plugin for contact angle measurements: https://imagej.nih.gov/ij/plugins/contact-angle.html\n# Open imageJ and check to see if \"Contant Angle\" is available under the \"Plugins\" tab and select it.\n# Open the image.\n# Select the two end points of the droplet where it meets the substrate using the \"drop points\" button (shown in red).\n# Select 5 points along the droplet surface and allow imageJ to run the fitting algorithm (shown in blue).\n# Click on the Menu button in the Contact Angle plugin toolbar.\n# Click Manual Points Procedure.\n# Open the results window to see the contact angle for a spherical approximation and also for elliptical approximation.\n\n== Drawbacks ==\n\n# This will not work if the substrate is not absolutely flat. The program needs to be able to draw a straight line that follows the surface of the substrate exactly after the user selects the two end points of the droplet.\n# Uses either a spherical or an elliptical approximation for the droplet. The user needs to be able to pick manually which approximation works better for their case.\n# The drop has to be very very small (ideally <3ul). The program neglects gravity.\n\n== For more information ==\n\n1. [https://www.researchgate.net/publication/328733959_Measuring_the_Contact_Angle_using_ImageJ_with_Contact_Angle_plug-in ResearchGate example]\n\n2. [https://www.youtube.com/watch?v=eLzcRvFneTM Youtube tutorial]\n\n{{Page data\n| license = CC-BY-SA-3.0\n}}\n\n[[Category:MOST methods]]"}