PhD opportunity: Rockets

Surgery with rockets
Self-propelled nano/microscale rockets have been developed that consume locally supplied chemical fuels to generate thrust, analogous to how large rocket engines ignite onboard propellants. Such rockets offer tremendous advantages as nano/microdevices. They can be designed for low or high velocities (up to 1000 body lengths/sec), can tow large loads, have remarkable design flexibility, and allow surface functionalisation with nanomaterials and biomolecules.1,2

Unlike their macroscale counterparts, these rockets have the advantage of harvesting their chemical fuel directly from their surrounding environment. In the proposed design for this project, a truncated conical cylinder, we will use water as a fuel. Water reacts with magnesium on the inner surface of the rocket, creating microscopic bubbles of hydrogen. As these bubbles expand they are driven towards the larger end of the rocket where they are ejected, driving the rocket forwards. These tiny catalytic rockets thus continue to move as long as the fuel is present. This eliminates the need for fuel storage or refuelling and allows for long, sustained propulsion throughout the medium, a particularly attractive feature for use in biological media. Furthermore, rockets that catalyse the bubble-thrust reaction are highly reusable as no rocket components are consumed during the propulsion and can thus be easily recovered (such as through simple filtration or magnetic collection techniques).

Precise motion control and advanced navigation capabilities can be achieved by using external stimuli, such as magnetic, heat, light, or acoustic fields. Together with the bubble-based propulsion, this allows nano/microrockets to operate effectively in a wide range of salt-rich, real-life environments, and in highly viscous biological media and materials.3,4

 

Research Activities
This work will be undertaken as part of a collaboration between Prof. Brown and Prof. Joe Wang at the University of California San Diego. The specific project determined by a combination of that level and the aptitudes of the prospective student. Projects are available in magnet design and guidance, rocket-suture coupling, tissue penetration, and performance envelope evaluation. Experimental, computational, and mixed projects are available. Students with a physics, materials, mechanical or electrical engineering background are encouraged to apply.

 

Expected Outcomes
This programme of work aims to develop a world-first medical technology that can revolutionise regenerative medicine and wound healing. The student can expect to produce high impact research publications and/or develop critical aspects of this technology.

 

References

1          Li, J., Esteban-Fernández de Ávila, B., Gao, W., Zhang, L. & Wang, J. Micro/nanorobots for biomedicine: Delivery, surgery, sensing, and detoxification. Science Robotics2(2017).

2          Li, J., Rozen, I. & Wang, J. Rocket Science at the Nanoscale. ACS Nano10, 5619-5634 (2016).

3          Garcia-Gradilla, V., Orozco, J., Sattayasamitsathit, S., Soto, F., Kuralay, F., Pourazary, A., Katzenberg, A., Gao, W., Shen, Y. & Wang, J. Functionalized Ultrasound-Propelled Magnetically Guided Nanomotors: Toward Practical Biomedical Applications. ACS Nano7, 9232-9240 (2013).

4          Manesh, K. M., Cardona, M., Yuan, R., Clark, M., Kagan, D., Balasubramanian, S. & Wang, J. Template-Assisted Fabrication of Salt-Independent Catalytic Tubular Microengines. ACS Nano4, 1799-1804 (2010).