Locating Cytroids

MSc assignment

Wouldn't it be great if we could send micrometer sized robots into the body to deliver drugs and perform microsurgery? This dream has been around ever since the sixties – you might have seen the movie “A fantastic voyage”. So why, after 50 years, do we not have these robots yet? The problem lies in the power supply. Batteries of that size are cumbersome and toxic. Power supply by external magnetic fields is horribly inefficient. The most efficient and elegant option would be to convert the energy needed from the surrounding liquid: just like swimming bacteria in a pond do.

What if we stop trying to make clumsy microrobots ourselves, and simply start with bacteria. Like androids, these would be some kind of organic robots on the microscale: a cytroid. We are extremely lucky that there exist a multitude of bacteria that possess a small permanent magnet inside their body and swim at speeds of up to 0.1 mm/s. These bacteria use the earth magnetic field to navigate. We can steer these bacteria to any location in the body using a static external magnetic field just slightly higher than the earth magnetic field. Successful experiments with targeted drug delivery into tumor sites have already been shown.

The big issue we are facing now is that inside the body we can only guess where the bacteria are. It would be great if we can locate them by some kind of metal detector. At the Magnetic Detection and Imaging group, Melissa van Loosdrecht, Lejla Alic and Bennie ten Haken have developed an instrument to detect magnetic particles inside the body (to locate sentinel lymph nodes for instance). Would it be possible to use their system to detect magnetic bacteria? What is the lower limit they can detect? What is the fundamental limit, and how should we improve the system?

This master thesis project is a joint effort between RAM and MDI, but you will spend the majority of your time in the latter. To be successful, it will help if you have a strong interest in low frequency analog electronics and spectrum analysis. Since you are working in the biomedical field, you must have some interest in biomedicine, but knowledge is not required. For more information, contact Leon Abelmann.