DFRobot Gravity Expansion Shield and Sensors for Arduino - DFRobot SEN0161-V2, This DFRobot SEN0161-V2 Analog pH Sensor Kit is specifically designed to measure the pH of a solution and reflect its acidity or alkalinity. The pH is a value that represents the acidity or alkalinity of a solution, also known as the hydrogen ion concentration index. The pH is a scale of hydrogen ion activity in a solution. pH has a wide range of uses in medicine, chemistry, and agriculture. Usually, the pH is a number between 0 to 14. Under thermodynamic standard conditions, pH=7, which means the solution is neutral; a pH<7 means the solution is acidic; a pH>7 means the solution is alkaline.As an upgraded version of pH meter V1, this product greatly improves the precision and user experience. The onboard voltage regulator chip supports the wide voltage supply of 3.3 to 5.5V, which is compatible with 5V and 3.3V main control boards. The free software library adopts the two-point calibration method, and can automatically identify two standard buffer solutions (4.0 and 7.0), making beginner experiments simple and convenient.With this product, a main control board (such as Arduino), and the software library, you can quickly build a pH meter, plug and play, with no soldering required. DFRobot SEN0161-V2 Gravity: Analog pH Sensor/Meter Kit V2