Research And Development Of An Online Biomass Monitoring System Based On Arduino Platform

Shaker flasks are commonly used in biotechnology research laboratories because of their low cost, ease of use, and the possibility to run experiments in parallel. In the related biological experiments, the growth status of the cells in shaker flask often needs to be constantly monitored, for example, to capture the window of log phase and induce protein expression for protein function and structure studies, to monitor the growth curve for microbial physiology and evolution studies, etc.Based on open source Arduino development platform, in this paper, a fast and accurate on-line monitoring system is established to measure and estimate the biomass concentration, and to improve the quality and efficiency of biological technology research, reduce the risk of contamination and experimenter’s physical labor. The main contents of the paper include:Firstly, the state of the art of biomass detection technologies are introduced, and the methods of optical detection in shaker flask culture are summarized. Then, it analyzes several kinds of turbidity measurement methods. Combined with the specific requirements in shaker flask culture, backward scattering detection scheme is adopted, and then designed the overall structure of the system. Furthermore, the related measuring principle is also introduced.Secondly, the light source and photoelectric detector are compared, analyzed and determined, and designed the corresponding driving circuit and signal conditioning circuit. According to the overall scheme of the system, the hardware design of the on-line monitoring system is carried out. The various modules of the system are introduced in detail, and accomplished the design, assembly and connection of the scattered light detection module. Then, it introduces the overall structure of system software, and designed the compensation subroutine to the inclination error of shaker table.Finally, the scattered light intensity experiments of various conditions(different incident angles, filling volumes and shaking frequencies) have been done to determine the optimal incident angle and the trigger angle. Then, the sensor system was successfully used to monitor the cell growth of Escherichia coli in a 500 ml shaker flask culture over a growth period of more than 20 hours. The results show that the monitoring system has achieved the expected results and requirements.