Magnetic-Guided Flexible Origami Robot toward Long-Term Phototherapy of H. pylori in the Stomach

TL;DR

The study addresses the challenge of treating H. pylori infections amid rising antibiotic resistance by leveraging photodynamic therapy (PDT). It introduces a magnetically guided origami robot (MGOR) composed of flexible printed circuit units that can be wirelessly charged and remotely actuated to deliver sustained light for PDT in the stomach, including a manual sequence that forms a triangular, compliant deployment structure. The MGOR operates in three morphologies (alpha, beta, gamma) and can transition between states to adapt to the gastric environment, with COMSOL-based magnetic-field analyses and physical tests validating motion and robustness. A wireless-energy scheme using a double spiral structure (DSS) and LC resonance demonstrates powering up to 15 LEDs at 80 mW each at short range, with measured voltages and distances indicating feasible in vitro operation; the approach lays groundwork for long-term, minimally invasive PDT against antibiotic-resistant H. pylori, though in vivo safety and autonomous control remain to be demonstrated. Key physical principles include Faraday's law, ${\varepsilon = -N \frac{d\Phi}{dt}}$, and LC resonance ${f = \frac{1}{2\pi\sqrt{LC}}}$ that govern the wireless power transfer aspects of MGOR.

Abstract

Helicobacter pylori, a pervasive bacterial infection associated with gastrointestinal disorders such as gastritis, peptic ulcer disease, and gastric cancer, impacts approximately 50% of the global population. The efficacy of standard clinical eradication therapies is diminishing due to the rise of antibiotic-resistant strains, necessitating alternative treatment strategies. Photodynamic therapy (PDT) emerges as a promising prospect in this context. This study presents the development and implementation of a magnetically-guided origami robot, incorporating flexible printed circuit units for sustained and stable phototherapy of Helicobacter pylori. Each integrated unit is equipped with wireless charging capabilities, producing an optimal power output that can concurrently illuminate up to 15 LEDs at their maximum intensity. Crucially, these units can be remotely manipulated via a magnetic field, facilitating both translational and rotational movements. We propose an open-loop manual control sequence that allows the formation of a stable, compliant triangular structure through the interaction of internal magnets. This adaptable configuration is uniquely designed to withstand the dynamic squeezing environment prevalent in real-world gastric applications. The research herein represents a significant stride in leveraging technology for innovative medical solutions, particularly in the management of antibiotic-resistant Helicobacter pylori infections.

Figures (7)

• Figure 1: Long-term Deployment System for Helicobacter pylori Photodynamic Treatment. (a) System overview showing an external device for possible intragastric environment detection, MGOR pose control, and wireless energy provision. (b) The external wearable device visualization schematic shall contain the external permanent magnet and the induction coil. (c) Illustration of the pose control mechanism of the MGOR, facilitated by permanent magnets and a spiral copper coil for wireless charging. (d) Flex-printed circuit board (F-PCB) unit. Scale bar: 1 cm. (e) Deployment strategy of the MGOR within the pyloric canal to minimize movement towards the pyloric antrum, a region conducive for H. pylori survival and replication.
• Figure 2: MGOR design and state transitions. (a) Design of the MGOR composed of three F-PCB cells with IPMs, stabilized in three distinct states (alpha, beta, and gamma) using an external magnetic field. (b) COMSOL simulations of the magnetic field distribution of the IPMs, highlighting fluctuations in internal forces during state transitions. (c) Demonstration of MGOR in its folded state, encapsulated within a capsule casing for oral administration, and its subsequent unfolding into the beta state.
• Figure 3: Comprehensive control methodology for MGOR state transition. The figure illustrates the use of an external controller, composed of two axially magnetized cylindrical magnets arranged in parallel, to facilitate the transition of the MGOR from beta to gamma state. The process includes maintaining the MGOR in the beta state, inducing divergent moments on the L-IPM and R-IPM by swift rotation of the EPM around the $x$-axis and linear movement along the $y$-axis, and inducing the flipping of the L-IPM when the IPMs enter an in-plane repulsive state.
• Figure 4: Physical verification of MGOR motion sequence. Keyframes from the operational footage demonstrating notable consistency with the motion sequence outlined in Figure 3.
• Figure 5: MGOR's robustness under force. (a) COMSOL simulations under 2-10N forces in vertical directions. (b) MGOR's full recovery post-manual force application.