DFRobot Gravity Expansion Shield and Sensors for Arduino - DFRobot SEN0161, What is pH? 'pH' stands for 'power of hydrogen', which is a measurement of hydrogen ion concentration. The pH scale ranges from 1 to 14, with 7 considered to be neutral. A pH less than 7 is said to be acidic and solutions with a pH greater than 7 are basic or alkaline.Need to measure water quality and other parameters but haven't got a low cost pH meter? The DFRobot analogue pH meter, has been specially designed for Arduino controllers and has convenient and practical 'Gravity' connector plus a host of useful features. It offers instant connection to your probe and your Arduino to get pH measurements at ± 0.1pH accuracy at 25℃. For most hobbyist this is a great accuracy range and it's low cost makes it a great tool for bio-robotics and other projects!The sensor has an LED which works as the power indicator, a BNC connector and PH2.0 sensor interface. To use it, simply connect the pH sensor with BNC connector, and plug the PH2.0 interface into the analogue input port of any Arduino controller.The sensor comes in a compact plastic box with foam for better mobile storage. Build your own pH meter gadget, or a water monitoring station for your water tanks. Use it for your aquaponics or fish tanks or other materials that need accurate pH measurements. DFRobot SEN0161 Gravity: Analog pH Sensor / Meter Kit For Arduino