We built a datalogger to gather data on the performance of a wave energy generator. It collected the data locally and also relayed it over a mobile phone data connection to allow remote monitoring - something rather handy when the generator was deployed, as it sat out in the English Channel.
Working with the client to specify the sensors, we designed and fabricated the circuit board to connect everything together; then wrote the firmware to perform the datalogging and uploading to the server API written by the client.