A pH sensor is an electronic device designed to measure the pH level of a solution, indicating its acidity or alkalinity. pH is a fundamental parameter used to quantify the concentration of hydrogen ions (H+) in a solution, on a scale ranging from 0 to 14. A pH of 7 is considered neutral, while values below 7 indicate acidity, and values above 7 indicate alkalinity.

The pH sensor comprises a pH-sensitive electrode and a reference electrode, both immersed in the solution being tested. The pH-sensitive electrode is typically made of glass and contains a special pH-sensitive membrane that responds to changes in hydrogen ion concentration. The reference electrode, often a silver/silver chloride electrode, provides a stable electrical potential against which the pH-sensitive electrode's potential is measured.

When the pH sensor is placed in the solution, hydrogen ions in the solution interact with the pH-sensitive membrane. This interaction generates an electrical potential that is proportional to the pH of the solution. The potential difference between the pH-sensitive electrode and the reference electrode is measured by the sensor and converted into a pH value using calibration data.

pH sensors come in various types, including handheld probes, inline sensors for continuous monitoring, and even wireless and smart sensors that can transmit data to a computer or smartphone.

These sensors find widespread applications in numerous industries, such as water quality analysis, agriculture, food and beverage production, pharmaceuticals, and environmental monitoring. They play a crucial role in ensuring quality control, optimizing chemical processes, and maintaining the desired pH levels for various applications.