Mini and Micro Propulsion for Medical Swimmers

Abstract

Mini and micro robots, which can swim in an underwater environment, have drawn widespread research interests because of their potential applicability to the medical or biological fields, including delivery and transportation of bio-materials and drugs, bio-sensing, and bio-surgery. This paper reviews the recent ideas and developments of these types of self-propelling devices, ranging from the millimeter scale down to the micro and even the nano scale. Specifically, this review article makes an emphasis on various propulsion principles, including methods of utilizing smart actuators, external magnetic/electric/acoustic fields, bacteria, chemical reactions, etc. In addition, we compare the propelling speed range, directional control schemes, and advantages of the above principles.

Fabrication and characterisation of short fibre reinforced elastomer composites for bending and twisting magnetic actuation

“…Biomimicry of aquatic propulsion has also led to the development of electro-active polymers that mimic the actuation surfaces of fish, with controlled bending and twisting configurations achievable and determined by the placement of electrodes on the surfaces [12]. Other systems use alternative propulsion techniques such as chemical reactions, bubble oscillation and bacteria mimicry [13]. Although these devices all show promise, there are still difficulties in developing swimmers that are easy to fabricate and reproduce, as well as being bio-compatible for use in the bio-medical field.…”

Frequency dependence of surface acoustic wave swimming

“…Different swimming strategies include using cilia and flagella, or by small multicellular organisms [25]. In many cases, the technological design of medical micro-robotics are inspired by, or similar to, swimming microorganisms [29]. For instance, the spiral micro-robot designed by Ishiyama et al [30], which is similar to some cilium propulsion mechanisms, or the artificial bacteria flagella [31,32] which use magnetics to induce motion.…”

“…For instance, the spiral micro-robot designed by Ishiyama et al [30], which is similar to some cilium propulsion mechanisms, or the artificial bacteria flagella [31,32] which use magnetics to induce motion. In addition to magnetic propulsion, a recent review [29] highlighted other methods of medical micro-robotic propulsion including 'propulsion by bubbles', 'propulsion by chemical reaction' and 'propulsion by biological mechanism' as methods of propulsion for medical swimmers. The experimental investigation of micro-swimming is challenging due to the difficulty in controlling the relevant key parameters, such as the wavelength of the cyclic distortion.…”

Experimental Verification for the Application Feasibility of Buckingham Pi Theorem in Designing a Scaled Model of Flagellated Swimmer with Traditional Resistive Force Theory

“…In recent years, micro underwater machines in low Reynolds number environment are widely studied and applied in different fields such as medical treatment and drug delivery [1] [2] [3]. Many factors should be taken into consideration in order to design a good swimmer at low Reynolds number environment.…”