Study On The Driving Characteristics Of Magnetic Control Diagnosis Capsules In Alimentary Canal

The wireless capsule endoscope?referred to as capsule endoscope?is a new medical digestive tract inspection technique with diagnostic function.The subject can ingest the controllable microcapsules by swallowing the capsules,and the examiner can diagnose and treat the digestive tract of the subject.The capsule endoscope avoids the hidden infections such as cross-infection and secondary trauma in the traditional tubular endoscope,reduces the pain during the examination,and broadens the visual field of vision and the breadth of detection.Magnetically driven capsule endoscopy has a good development and application prospect in the field of clinical medicine.However,there are currently problems such as long detection period,short battery life,limited detection location,difficult diagnosis and accurate positioning of the lesion.In this paper,the microcapsule endoscope driven by external magnetic source is taken as the research object.In the digestive tract environment where human viscoelastic tissue and viscous liquid exist,the shape optimization of the capsule,the characteristics of magnetic driving force,the driving magnetic source and its A series of related researches have been carried out on the magnetic field characteristics,including:Based on the swallowing process of esophageal tissue and its viscoelastic constitutive model,a frictional resistance model of capsule endoscope movement in the human esophagus was established.The relationship between the geometry and motion parameters of the capsule and the force on the esophageal wall and the force of the capsule were explored in the state of movement of the capsule in the esophagus.Taking the structural parameters and motion parameters of the capsule as variables,the orthogonal simulation experiments of₉L3³ were designed,and the finite element transient simulation of the capsule in the viscoelastic esophageal model was carried out.At the same time,the damage stress?₀ was put forward as a parameter index to evaluate the degree of esophageal damage caused by capsule.The result was analyzed by the pole variance analysis,and the influence and significance of the shape coefficient?_h and the outer diameter of capsuleD_a on the stress of esophagus are obtained.The results are valuable for the shape optimization of esophageal capsule endoscopy.A reference mathematical model of intestinal peristalsis was proposed.Combined with the two resistance models of capsule movement in the intestine,the magnetically controlled capsule endoscope was driven in the intestinal tract,and the viscous fluid and viscoelastic intestinal wall were coupled.Characteristic study.Firstly,according to the movement characteristics of the capsule endoscope in the intestine,the model of the movement resistance of the capsule in the intestine was proposed.Secondly,the Texture Profile Analysis?TPA?experiment and puncture experiment of the isolated pig intestinal wall were performed on the texture analyzer.The physical parameters were analyzed to verify that it could replace the human intestinal tract for capsule ex vivo experiments;combined with the obtained intestinal physical parameters,the capsules of the two shapes were carried out under different fluid dynamics?and intestinal diameter D fluid-solid coupling intestinal environment.The simulation was carried out to analyze the numerical characteristics of the force of the capsule,the stress and strain of the intestinal wall,and the viscous fluid.Finally,the relationship between the driving characteristics of the capsule and the structural parameters of the intestine was given.The driving characteristics of the internal permanent magnet?IPM?of the capsule controlled by the external permanent magnet?EPM?were studied.Firstly,U-type EPM is taken as an example to give the control principle and control conditions of magnetic drive,and three kinds of control attitudes between permanent magnets are proposed.The columnar shape of axial and radial magnetization is established under the condition of external magnetic field.The spatial force model of IPM;on the basis of the proposed theory,the influence of the relative position parameters of EPM and IPM on the driving electromagnetic force and torque is analyzed by magnetic field simulation;the shape optimization simulation of EPM is carried out to improve the driving of the capsule.The effects of non-magnetic solid and fluid fields on the EPM magnetic field were analyzed by intestinal magnetic fluid-solid coupling simulation.The Helmholtz coil group model was established by analyzing the magnetic drive characteristics of the capsule with the Helmholtz coil as the fixed magnetic source.Firstly,the basic principle and driving characteristics of electromagnetically driven capsules are expounded.The magnetic field model of the corresponding coils is given.The characteristics of the energized magnetic field of Helmholtz coils are analyzed.The conditions for generating a uniform magnetic field in a single coil are determined by electromagnetic simulation.A square coil magnetic field model with more practical applications has been established.Based on the above research,combined with the safety standard of electromagnetic protection,two sets of orthogonal Helmholtz coil group models are designed.Finally,by applying harmonic currents with?/2 phase differences in the electromagnetic field,the capsules can be driven.The spatial rotating magnetic field verifies the feasibility of the spatial rotating magnetic field driving method.