Vibrational Micro-robots in Viscoelastic Biological Tissues

Wireless micro-robots hold great potential for minimally-invasive medicine, since they may allow for targeted drug delivery, in vivo sensing, stimulation, and even new surgical procedures. However, the biggest hurdle for biomedical applications is the penetration of real biological media, for instance, mucus, vitreous, blood clots and tumour tissues. Most current micro-/nano-robots can propel in water, however, the same propulsion mechanisms do not readily transfer to viscoelastic biological media. One major bottleneck is that it is not possible to exert enough force for propulsion in a system that could one day also accommodate a human. The overall goal of this proposal is to develop vibrational microdevices that can actively propel and wirelessly sense in viscoelastic biological tissues. The excited mechanical vibration is coupled with the frequency-dependent fluidic rheology to increase the energy release rate, to reduce the penetration force needed for tissue rupture, and thus to facilitate an easier penetration of the tissues. We will investigate the fundamental mechanisms of propulsion at low Reynolds number in viscoelastic materials. The microrheology of the biological fluids will be measured and modelled, and it will allow us to optimize the shape and gait of the micro-robot to exploit the complex rheological properties of biological tissues and generate propulsion. The proposed work will also advance three-dimensional fabrication technologies for asymmetric micro-/nanostructures as key elements to interact with tissues to facilitate efficient locomotion. We will also develop novel sensing methods for in vivo sensing and localization of the microdevices. Our research will lead to a new class of micro-robots - the VIBEBOTS that will be able to actively penetrate real tissues, and open up outstanding opportunities for useful biomedical applications.