Biologically-Inspired Robotic Microswimmers for Novel Drug Delivery Systems
A biomimetic, microscale drug delivery system with active propulsion is demonstrated. The device is based off of the propulsion system of bacteria such as Escherichia coli and Salmonella typhimurium, and makes use of flagella filaments isolated from S. typhimurium. An external rotating magnetic field is generated by a set of electromagnetic coils in an approximate Helmholtz configuration. The magnetic field induces rotation in a flagella conjugated magnetic bead. The flagella act as both a fluidic actuator for device propulsion and as a coupler for a polystyrene bead, which is used in place of a specific drug delivery system, such as a drug filled vesicle. When the flagella are rotated, they create propulsion, as in natural, polarly-flagellated bacteria. Directed motion of the robot is achieved through polymorphic transformation of the flagella filaments, as found in natural bacteria.
Magnetic Field generated by coils in an approximate Helmholtz configuration. The magnetic field was simulated using COMSOL multiphysics to ensure that at the middle point between the coils, where the sample is to be placed, has a uniform field. A uniform field is necessary to ensure that the devices are only actuated by the rotating magnetic field. The coils are 3.5cm in diameter and separated by 5.8cm. An actively powered, biomimetic drug delivery system was designed and analyzed. This system utilizes bacterial flagella to create propulsion as in natural, polarly flagellated bacteria. A rotating magnetic field generated by AC power supplies connected to coils in an approximate Helmholtz configuration create a homogeneous magnetic field that rotates a magnetic bead, thus rotating the flagella to create propulsion. Based on the simulations of the system, the swimming velocity of the device should be linear with the applied field frequency. The speeds predicted by this model are similar to that of flagellated bacteria (≈30μm/s) with the same flagellar rotational speed.
Collaborators: Prof. Kenny Breuer @ Brown, Prof. Tom Powers @ Brown
