Electrochemical pH Sensor
The measurements and a real time clock reading are saved in nonvolatile memory and retrieved via a USB cable when the sensor is retrieved. These data can be converted to pH using a calibration table. We hope that Salinity and other properties might be extracted from the data using multivariate analysis.
Low Power Operation
The sensor uses a low power ATtiny85 microcontroller that is programmed using the Arduino IDE, to achieve very low power operation. The ATtiny85 can be put to sleep and in this state uses less than 200 uA of current when running through an efficient inverter from 12V batteries. The rest of the system is turned on and off by the ATtiny85, so the high power used by the Arduino and other devices only operates for as long as is necessary to take measurements of the electrochemical voltages and other readings (about 5 seconds).