Underwater optical sensorbot for in situ pH monitoring

Continuous underwater observation is a challenging engineering task that could be accomplished by development and deployment of a sensor array that can survive harsh underwater conditions. One approach to this challenge is a swarm of micro underwater robots, known as Sensorbots, that are equipped with biogeochemical sensors that can relay information among themselves in real-time. This innovative method for underwater exploration can contribute to a more comprehensive understanding of the ocean by not limiting sampling to a single point and time. In this thesis, Sensorbot Beta, a low-cost fully enclosed Sensorbot prototype for bench-top characterization and short-term field testing, is presented in a modular format that provides flexibility and the potential for rapid design. Sensorbot Beta is designed around a microcontroller driven platform comprised of commercial off-the-shelf components for all hardware to reduce cost and development time. The primary sensor incorporated into Sensorbot Beta is an in situ fluorescent pH sensor. Design considerations have been made for easy adoption of other fluorescent or phosphorescent sensors, such as dissolved oxygen or temperature. Optical components are designed in a format that enables additional sensors. A real-time data acquisition system, utilizing Bluetooth, allows for characterization of the sensor in bench top experiments. The Sensorbot Beta demonstrates rapid calibration and future work will include deployment for large scale experiments in a lake or ocean.