Autonomous sensor capsule for usage in bioreactors

An autonomous biochemical sensor capsule for the remote monitoring of an algae culture cultivated in a photobioreactor is presented. The encapsulated system has a spherical shape with a diameter of 44 mm. Radio communication with a carrier frequency of 433 MHz is used to transfer the acquired sensor data in the bioreactor to a base station outside. Experiments with the first prototype inside the bioreactor filled with nutrient solution were performed to determine the reliability of the communication link. The packet error rate converged to 26% and the path loss on average was 96 dB. The functionality of the signal processing chain of acquired biochemical sensor values was evaluated using an experimental setup. Our second capsule prototype with potentiometric sensors demonstrates the pH-measurements of different buffer solutions dropped on the sensor electrodes with a pipette.