Ion-selective electrodes (ISEs) are sensors designed to measure the concentration of specific ions in a solution. They work by generating a voltage that corresponds to the ion concentration, allowing for precise and selective analysis. Commonly used ISEs include those for sodium, potassium, and chloride ions, making them valuable in various fields such as environmental monitoring and clinical diagnostics. The construction of an ISE typically involves a sensing membrane that selectively interacts with the target ion. This membrane can be made from various materials, including glass or polymer, depending on the ion being measured. ISEs are essential tools in laboratories and industries for ensuring accurate measurements of ion concentrations.