The goal of our project was to implement a fast biosensor on a mobile robot. This bridges the gap between biology and electronics, opening up many new and exciting possibilities. We not only managed to get every part working individually, but implemented all of them on the robot. The fully functional robot can perform each step necessary to sense a molecule in air and I performs each of these steps completely autonomously. The video below demonstrates how biology, software and hardware act in concert to make AROMA move based on the concentration of an analyte.
Description of our procedure
OverviewHere we briefly describe how each step is implemented in our final setup and link to the respective pages for further illustration.
DrivingAROMA houses a large battery and uses an electric four-wheel drive system. This allows us to move around freely, guided by our high-level algorithm. As soon as AROMA arrives at the place to measure we stop and continue with step two.
UptakeThe next step is to bubble air containing the analyte into our medium. We use a custom controlled air pump to achieve this. After each bubbling step we need to replace the medium. This is achieved with two syringe pumps each holding a maximum volume of 60 ml. One syringe is filled with fresh medium and the other one holds the waste solution. The bubbling then divides into the following steps: First fresh medium is pumped into our bubbling container. Secondly, we bubble air through it. Now a small sample is transferred to the microfluidic chip for measurement. The final step is then emptying the bubbling container with the second large syringe pump.
Sensing and measurementOur E. coli are attached to the floor of the glass plate of the microfluidic chip using antibodies and rotate in different patterns depending on the concentration of the analyte. Our custom microscope images the movement response of E. coli to concentration changes of our target molecule.
AnalysisWe developed imaging processing software to read out the movement of the bacteria. This happens in real-time on the laptop attached to AROMA in order to visually show the image analysis. As soon as we obtain the data the robot decides where to move next in order to find the source of the molecule. The workflow is then repeated until the source of the target molecule has been located.