Design and testing of a novel gastrointestinal microrobot

Ferrite Concentrating and Shielding Structure Design of Wireless Power Transmitting Coil for Inductively Coupled Capsule Robot

High permeability material, especially the ferrite, has been widely used in wireless power transfer (WPT) to enhance the power transfer efficiency (PTE). However, for the WPT system of inductively coupled capsule robot, the ferrite core is solely introduced in power receiving coil (PRC) configuration to enhance the coupling. As for the power transmitting coil (PTC), very few studies focus on the ferrite structure design, and only the magnetic concentrating is taken into account without careful design. Therefore, a novel ferrite structure for PTC giving consideration to the magnetic field concentration as well as the mitigation and shielding of the leaked magnetic field is proposed in this paper. The proposed design is realized by combing the ferrite concentrating part and shielding part into a whole and providing a low reluctance closed path for magnetic induction lines, thereby improving the inductive coupling and PTE. Through analyses and simulations, the parameters of the proposed configuration are designed and optimized in terms of average magnetic flux density, uniformity, and shielding effectiveness. Prototypes of PTC with different ferrite configurations are established, tested, and compared to validate the performance enhancement. The experimental results indicate that the proposed design notably improves the average power delivered to the load from 373 mW to 822 mW and the PTE from 7.47% to 16.44%, with a relative percentage difference of 119.9%. Moreover, the power transfer stability is slightly enhanced from 91.7% to 92.8%.

Ingestible Functional Magnetic Robot with Localized Flexibility (MR-LF)

The integration of an ingestible dosage form with sensing, actuation, and drug delivery capabilities can enable a broad range of surgical-free diagnostic and treatment strategies. However, the gastrointestinal (GI) tract is a highly constrained and complex luminal construct that fundamentally limits the size of an ingestible system. Recent advancements in mesoscale magnetic crawlers have demonstrated the ability to effectively traverse complex and confined systems by leveraging magnetic fields to induce contraction and bending-based locomotion. However, the integration of functional components (e.g., electronics) in the proposed ingestible system remains fundamentally challenging. Herein, the creation of a centralized compartment in a magnetic robot by imparting localized flexibility (MR-LF) is demonstrated. The centralized compartment enables MR-LF to be readily integrated with modular functional components and payloads, such as commercial off-the-shelf electronics and medication, while preserving its bidirectionality in an ingestible form factor. The ability of MR-LF to incorporate electronics, perform drug delivery, guide continuum devices such as catheters, and navigate air-water environments in confined lumens is demonstrated. The MR-LF enables functional integration to create a highly-integrated ingestible system that can ultimately address a broad range of unmet clinical needs.

Efficient Power Receiving Coil With Novel Ferrite Core Structure for Capsule Robot

Power receiving coils (PRCs) with ferrite cores are widely used in wireless power transfer (WPT) for capsule robots (CRs) to enhance the power transfer efficiency (PTE). However, due to the large demagnetizing factor, the traditional one-dimensional hollow cylindrical ferrite core has its limitations in volume and performance improvement, which needs to be reconsidered. To this end, we propose a novel PRC equipped with a delicate, lightweight, and more efficient ferrite core structure in this paper. Different from the traditional ferrite core structure, the proposed design composed of distributed ferrite cores and end covers aims to minimize the negative impact of demagnetization on PTE and enhance the magnetic flux concentration. Based on the analysis of the PTE and mutual inductance, influence of the introduced cores on the WPT system is emphasized. The relationship between the change of ferrite core structures and the demagnetizing factors, as well as the effective permeability, is analyzed and simulated. Prototypes of PRCs with different ferrite core configurations are established, tested, and compared to validate the performance enhancement. Experimental results on the power delivered to the load (PDL) and PTE indicate that the proposed design has a volume reduction of 24.4% but performance enhancement of 36% compared with the traditional one with hollow cylindrical ferrite core, thanks to the structure-based demagnetizing factor optimization.

Design and analysis of a wireless power transfer system for capsule robot using an optimised planar square spiral transmitting coil pair

BACKGROUND

The wireless power transfer system (WPTS) is a promising way to continuously provide efficient and stable power for gastrointestinal capsule robots with active movement ability.

METHODS

The proposed WPTS using an optimised planar square spiral transmitting coil pair with space-saving structure can flexibly adjust the distance between the coils according to the patient's condition, and thus has better applicability. To improve power transfer efficiency and uniformity of the generated magnetic field, design parameters are discussed and optimised based on the analytical calculation and simulation analysis.

RESULTS

The power demand can be guaranteed with spacing distance of 350-500 mm and the peak received power of 1124 mW with a remarkable transfer efficiency of 7.8% can be obtained when the spacing reaches the minimum. The human electromagnetic exposure safety in different situations is also discussed and verified.

CONCLUSIONS

The WPTS can provide power for capsule robots safely and efficiently.