Research On A Human Esophagus-inspired Peristalsis Device

The purpose of developing a human esophagus-inspired peristalsis device is to generate peristaltic movements and to investigate the relationship between peristalsis motion and food bolus properties quantitatively,based on engineering techniques.The novel device will provide a solution on food categorization and diet management for dysphagia patients.To investigate the insight relationship between peristalsis motion and food bolus properties,the contraction pressure,the speed and the profile of peristalsis must satisfy the requirement specifications which have been measured clinically.Due to the limitations in structure,material composition and actuation system,most of the current humanoid peristalsis devices fail to meet the specifications relative to contract pressure,speed or profile of peristalsis.A novel soft-bodied peristalsis device with multiple embedded layers of inflatable chambers is proposed and developed to generate peristalsis.To achieve the peristalsis requirements,the research has been divided into four sections:soft body structure design,theoretical model of structure deformation,experiments on soft body deformation and experiments on food bolus conveyance.To overcome the limitations of peristalsis devices on contraction pressure,peristalsis velocity and perisltasis continuity,a novel soft-bodied structure with four-chamber stacked is presented and implemented to mimick the human esophageal peristalsis.The structure is fabricated with soft silicon rubber,with a cylinder located at its central axis and twelve stacked layers of inflatable chambers around the cylinder.Four chambers are arranged evenly at each layer.Finite element analysis(FEA)was used to determine the structure parameters of the device,ensuring a continuous and smooth shape of the deformed food passage.The prototype of the peristalsis device was fabricated using silicon rubber.The food passage,which lies in the middle of the device,is with length of 250mm and internal diameter of 20mm,according to the geometrical size of adults' esophagus.For the purposed of generating smooth and continuous peristalsis,a control model which includeing a geometry model and a food bolus internal pressure model,is established for the peristalsis device.A geometrically simplified model composed of seven elastic beam-shaped elements was presented,based on the device structure in which embedded chambers are evenly arranged along the food passage.In this model,the mechanical properties of the silicon material,the geometry deformation of elastic elements and the force constraint of each element are considered.The geometric deformation and the force balance system of each element were analysed,as well as the force balance system of differential element.The simulation results show that the deformed profile of the food passage element is smooth and continuous.A mathematical model was presented to study the internal pressure of food bolus during peristalsis movement.Simulation results show that the food bolus internal pressure is affected by its location and dynamic parameters of the device.The model results ensure the achievement of food bolus transport in the novel device.The performance of circumferential constriction and peristaltic transport of the peristalsis device was investigated experimentally.The air pressures inside chambers were regulated by pneumatic proportional valves.The deformation of the internal conduit was captured and recorded by electromagnetic ar ticulography.The profile of the conduit could be altered by controlling air pressures.And a continuous shape could be achieved while three layers of chambers were pumped simultaneously.The recorded displacement of articulography sensor rise up to around 8mm when pressures climbs up to 64kPa in three layers of chambers,which indicates that the developed peristalsis device is capable of modelling the circular muscle constriction and making a completely closure.The deformation results in simulation and experiment were compared and analysed.All average relative differences of the conduit deformation at seven articulography sensors',positions were less than 10%.The minimum average relative difference was about 2.1%.The food boluses were formulated on a fluid concentration basis covering a wide range viscosity,from 0.8Pa·s to 16.0Pa·s.IBP,of which the value was between 0.15kPa and 6.2kPa,was found to increase significantly with higher food bolus viscosity.MILP was non-sensitive to food viscosity.The minimum MILP was about22kPa and was greater than specification of 4kPa.The value of PFI increases with the viscosity of food bolus.The performance of the peristalsis device meets the technical requirements.