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 activity of the target ion, allowing for precise and selective analysis. Commonly used in laboratories and environmental monitoring, ISEs can detect ions such as sodium, potassium, and chloride. These electrodes consist of a sensing element, often made from a membrane that selectively interacts with the target ion. The response of the electrode is influenced by factors like temperature and pH, making calibration essential for accurate measurements. ISEs are valuable tools in fields such as chemistry, biology, and water quality testing.