A Localization Method for Untethered Small-Scale Robots Using Electrical Impedance Tomography

Untethered small-scale robots can be potentially used in medical applications, such as minimally invasive surgeries and targeted drug delivery. This article introduces a new localization method using electrical impedance tomography, which is an emerging medical imaging technique, to dynamically track small-scale robots. The proposed approach provides the electrical conductivity distribution within the robot workspace from a set of electrical stimulations and voltage measurements gathered from eight electrodes placed at its boundary. The position of the robot can be deduced from the conductivity map that is reconstructed with the contrast in electrical properties between the robot and the background medium. This method is experimentally validated by successfully tracking the 2-D motion of four different magnetically actuated robots within a cylindrical arena (30 mm in diameter and 4.2 mm high). The smallest detected robot is 1.5 x 1.5 x 1 mm(3). The proposed tracking method provides a noninvasive technology with low-cost and high-speed potential that would be significant and useful for the position feedback control of untethered devices for biomedical applications in the future.