B0-field-driven capsule endoscope with swimming tails for propulsion : design study Introduction Capsule endoscopy has proven to be a useful tool for gastrointestinal diagnosis (1). Part of the colon is not reachable by traditional endosocpy or by colonoscopy; the capsule endoscopy was superior to push enteroscopy in the diagnosis of recurrent bleeding in patients who had a negative gastroscopy and colonoscopy near these lesions (2). The shortcomings of today, though, is capsule endoscope depends on natural peristaltic motion created in the intestines and no active control to go back the disease site is possible nor precise localization of the site in diagnostic cross sectional images have not yet reported. Several studies have shown that active control of capsule may overcome these issues (3-5). We report our preliminary design study of capsule endoscope using a MRI's constant magnetic field to propel a capsule and navigate the endoscope by real-time MR imaging. Results Setting the length of swimming tail 10 [mm], the width 5 [mm] and the total thickness 0.15 [mm], numerical analysis showed that traveling wave can be amplitude 14 [m] and frequency of 12.836 [kHz] (the third resonance frequency). These analysis is base on an assumption that the current in the tails is 3.7 [mA] and the MRI's magnetic field is 3 [T]. Figure 3 shows the decomposed traveling wave to natural mode shapes given by Equation 1. Gabor Kosa, Peter Jakab, Ferenc Jolesz, Nobuhiko Hata Faculty of Mechanical Engineering, Technion, Haifa, Israel Department of Radiology, Brigham and Women’s Hospital, Boston, MA Aim the purpose of this study is to design the capsule endoscope driven by the static field of MRI and assess the feasibility of fabrication. We present our preliminary design of the endoscope and simulate the propulsive force and power source required to drive the capsule inside stomach. Method Conclusion We present a novel propulsion method taking advantage of the static field of the MRI that can be downscaled by novel MEMS technologies. This hybrid endoscopic/MRI technology will enable new medical abilities that cannot be imagined at this point of time. Further work will be conducted to fabricate this capsule endoscope in real world settings. Acknowledgements This publication was made possible by Grant Number 5P01CA067165,5U41RR019703, 5R01CA109246, 1R01CA111288, 5U54EB005149, from NIH, and 9731748 from NSF. The authors thank members of National Center for Image Guided Therapy for support and contribution to this study. Fig.1: Steerable swimming micro robot for the MRI. Fig 3: (top) Natural mode shapes of the beam , (bottom) traveling waves Fig. 2: Spermatozoa Swimming from the Lugworm Arenicola marina A. A. PACEY, J. C. COSSON AND M. G. BENTLEY (1994). t=0[sec] t=/3/[sec] t=2/3/[sec] t=/[sec] t=4/3/[sec] t=5/3/[sec] t=2/[sec] Fig. 4: Illustration of the motion of the tail by sequel snapshots of the tail simulation at ten different time-points. The time difference between each position is . The positions are designated by roman numbers and the time points I and X are identical. in case a figure takes more than 2/3 of column width. Following Taylor’s theoretical basis (8) and inspired by the flagellar movement of microorganisms in low Reynolds number hydrodynamic field (6-8), the first author of this paper (GK) have shown that the oscillating beam can create approximated sinusoidal traveling wave in viscous flow and produces propulsion force effectively (9-11). The sinusoidal wave from such tail can be decomposed as, w (d ) ( x,t ) w sin ( x Ut ) w(sin x cosUt cosx sin Ut ) (Cs k cosUt Cc k sin Ut k 1 ) k ( x) g k (d ) ( t ) k1 k ( x) G k sin(t k ) k1 3 k ( x) (Equation 1). Extending this preliminary finding with single oscillating beam, we propose elongated tail with three coils attached in a row (Fig. 1). To create the phases and amplitudes in (Equatoin 1) by three coils in the tail, one has to design beam's dynamical response to coil moved by Lorentz force in B0 field. The motion of the tail with three coils is governed by the Euler-Bernoulli beam equations, which is, w i ( x, t ) k ( i ) ( x)g k (t ) k1 i 1 , 2,3 (Equation 2) By taking into account the boundary conditions of the beam, and boundary condition between the two coils, solution of the problem has the following form: m 1 2 w 1 ( x,t ) t 2 c w 1 ( x,t ) t ˆ K 1 4 w 1 ( x,t ) x 4 0x [0, 1 L ] m 2 2 w 2 ( x,t ) t 2 c w 1 ( x,t ) t ˆ K 2 4 w 2 ( x,t ) x 4 0x [ 1 L , 2 L ] m 3 2 w 3 ( x,t ) t 2 c w 1 ( x,t ) t ˆ K 3 4 w 3 ( x,t ) x 4 0x [ 1 L ,L ] (Equation 3) ,which describes k-th modal function in a segment. From this, we can numerical analyze amplitude and frequency of the waveform. Based on (Equation 3) , one can simulate an input currents to each coils to make the beam to vibrate in a sinusoidal traveling wave, as flagellar movement (Figure 2). The propulsive velocity of such tail will be 3 [mm/s]. The tail structure shown in Fig. 1 in which the tails are tilted by 30º to the axis of the robot will achieve a maximal propulsive velocity of 7.9 [mm/s]. The force that is created in the tail is 5.5 [mN]. Contact: Nobuhiko Hata, Email: hata@bwh.harvard.edu References 1. Iddan, G., Meron, G., Glukhovsky, A., Swain, P., Nature 405, (2000) 417. 2. Ell, C., Remke, S., May, A., Helou, L., Henrich, R., Mayer, G., Endoscopy 34, (2002) 685-689. 3. Sendoh, M., Ishiyama, K., Fabrication of Magnetic Actuator for Use in a Capsule Endoscope, IEEE Transactions on Magnetics, 39(5), (2003), 3232-3234. 4. Stefanini, C., Menciassi,A. Dario, P., International Journal of Robotics Research 25(5-6), (2006) 551-560. 5. Gorini S, Quirini M, Menciassi A, Pernorio G, Stefanini C, and Dario P, Proceeding of IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics, (2006). 6. Happel, J. and Brenner, H., Kluwer Boston, (1983). 7. Colgate, J.E. and Lynch, K.M., IEEE Journal of Oceanic Engineering 29, (2004) 660-673. 8. Taylor, G.I, Proceedings of the Royal Society A, (1952) 225-239. 9. Kósa, G, Doctoral Thesis, Technion Israel Institute of Technology, (2006). 10.Kósa, G., Shoham, M. and Zaaroor M., IEEE Conference on Robotics and Automation (ICRA05), (2005) 1339-1343. 11.Kósa, G., Shoham, M. and Zaaroor M., IEEE Transactions on Robotics, 23(1), (2007) 137-150. This is possible by by taking into account View publication stats View publication stats