Dynamics modeling and analysis of a swimming microrobot for controlled drug delivery

Document Type

Article

Publication Date

4-1-2009

Abstract

Dynamics modeling and analysis of a tiny swimming robot, which is composed of a helix type head and an elastic tail, is presented in this paper. The microrobot is designed for controlled drug delivery. It is at the micrometer scale and suitable for a swimming environment under low Reynolds number (Re). The head of the swimming robot is driven by an external rotating magnetic field, which enables it to be operated wirelessly. The spiral-type head accommodates communication and control units and serves as the base for the elastic tail. When a rotating magnetic field is applied, the head rotates synchronously with the field, generating and propagating driving torque to the straight elastic tail. When the driving torque reaches a threshold, dramatic deformation takes place on the elastic tail. The tail then transforms into a helix and generates propulsive thrust. The entire tail also serves as a drug reservoir. This paper focuses on analyzing the dynamics of the microrobot using resistive force theory (RFT), and comparing the propulsion performance with other rigid-body microrobots.Note to Practitioners-In this paper, we present a swimming microrobot which is designed to be small enough to be injected into a human body to perform controlled drug delivery. In order to safely inject microrobot into human bodies, the diameter of the microrobot needs to be or smaller than 0.8 mm, which makes the Reynolds number (i.e., the ratio of inertial force to viscous force) very low. In such a low Re environment, traditional propulsive methods, such as fish-like actuators, scallops and rigid oars which depend on reciprocal motions, cannot work efficiently or cannot function at all due to their underlying inertial forces propulsion mechanism. Inspired by the bacteria in nature, our design has the unique feature of integrating a spiral-type head and an elastic flagellum-like tail, which enables the microrobot move freely in a low Re environment. Driven by external magnetic field, the microrobot can be operated wirelessly. In the case of drug delivery, the elastic tail not only serves as a drug reservoir, but also generates propulsive force when proper driving torque is provided and its deformation is triggered. Therefore, the energy efficiency of the system is improved compared with other rigid-body microrobots carrying a sphere drug payload. © 2006 IEEE.

Publication Title

IEEE Transactions on Automation Science and Engineering

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