A pH sensor is a device used to measure the acidity or alkalinity of a solution. It works by detecting the concentration of hydrogen ions in the liquid, which determines its pH level on a scale from 0 to 14. A pH of 7 is considered neutral, while values below 7 indicate acidity and values above 7 indicate alkalinity. These sensors are commonly used in various fields, including agriculture, water quality monitoring, and laboratory research. They help ensure optimal conditions for plant growth, assess the safety of drinking water, and support scientific experiments by providing accurate pH measurements.