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, a