Sens-o-Spheres III - Characterization of new bioreactor systems through position- and time-resolved acquisition of process measurement signals using mobile, miniaturized sensors

Sensors are abundantly used to control and monitor bioprocesses. Typical bar-shaped sensor electrodes are installed via a standard port into the bioreactor, representing a measured value only in one spot of the reactor. Hence, information regarding process parameters which are distributed inhomogeneously cannot be acquired comprehensively. This can lead to false control settings and thus to suboptimal or unexpected outcomes. Moreover, the sterile access for sensors can cause problems when the process monitoring for the reactor system is not constructively foreseen. An example for such a reactor is the commonly used Erlenmeyer flask.

Sens-o-Spheres concept — Fig. 1: Sens-o-Spheres application scenarios.

The project’s aim is the further development of location-independent, fully autarkical, minimally disrupting micro sensors, the so called Sens-o-Spheres, in order to address these problems. In addition to locatisation of the micro-sensors the three process measurement values temperature, pH-value and dissolved oxygen will be implemented. The sphere consists therefore of a functionally integrated antenna within the encapsulation for the use in biotechnological processes, a microcontroller for the functional coordination, and a rechargeable energy supply.

SoS concept new — Fig. 2: Sens-o-Spheres conceptual design.

This spherical measurement device moves through the process volume independently and transmits the recorded measuring values wirelessly via radio frequency waves to a receiver. The external receiver, consequently, feeds the recorded signal in the process control system. Due to its small physical dimensions the Sens-o-Spheres can be used in well-plate as well as in laboratory fermenters with a volume of several liters. Due to the sensor’s flow following property mixing and transport processes in a bioreactor are unaffected. Since the sensor ports are not used the risk of a possible contamination of the process with external germs is reduced. Another advantage is the easy numbering-up of sensors as one base station can handle several Sens-o-Spheres.