Research On Degradable Capacitive Displacement Sensor For Implantable Medical Treatment

A biodegradable device is a device made of degradable materials.It can not only realize the designed function,but also can be completely degraded under certain conditions after the task is completed,leaving no traces.This feature makes it easy to implant The field of medical care plays an important role.However,in the face of practical applications,biodegradable devices still have some problems: In terms of materials,traditional electronic devices mostly use non-bendable and non-degradable materials,which are not suitable for biodegradable devices.In terms of devices,displacement sensors are needed to monitor the feed rate of implantable drug delivery systems.However,there is currently no research on biodegradable displacement sensors.Therefore,this paper has developed a high-performance implantable displacement sensor that is degradable and harmless to the human body.In order to achieve the above goals,it is necessary to ensure that the sensor substrate,electrodes and packaging are all biodegradable materials.Therefore,this paper uses natural chitosan as the basic material to prepare the film substrate.In order to obtain a substrate with better flexibility and a smaller surface roughness,Insect epidermal protein is added to obtain a doped film.On this basis,this paper designs and manufactures a degradable displacement sensor.The sensor uses a doped film as a substrate,and uses magnetron sputtering to prepare interdigitated zinc metal electrodes on the substrate,and then adds a doped film as a package protection layer.The sensor uses the principle of capacitance sensing to monitor displacement by measuring the inductive capacitance generated when the human body approaches the sensor.In order to study the sensor performance,first of all,this article characterizes the electrical performance of the displacement sensor.Experiments show that the capacitance change is inversely proportional to the displacement.The sensitivity can reach up to 68.5n F/mm.It can be used to measure micron-level displacement.The detection range is 0-4mm,and has a high response speed and stability.Subsequently,this article starts from the material to study its degradation performance and characterizes the controllable degradation ability of the film substrate.The film will be completely degraded within 3 hours in deionized water.The degradation rate of the film will be the same when the p H value decreases or the temperature rises.Will increase faster.In order to study the mechanical strength of the sensor,this paper characterizes the effect of adding protein on the film substrate.The results show that compared with pure chitosan film,the elongation and toughness of the doped film at a concentration of0.5% are increased by 77% and 173,respectively.%,the root mean square roughness(Rq)is reduced by 12.8%,and the substrate has excellent flexibility and surface roughness,which is very beneficial to electronic devices.Furthermore,this article studies the degradation performance of commonly used metals,and the results show that electrodes made of zinc will complete degradation within 2 days,and this speed is suitable for the preparation of biodegradable devices.Finally,we studied the overall degradation performance of the sensor.The sensor will disintegrate and deform within 10 minutes in deionized water,the film will be completely degraded within 3 hours,and the metal will be completely degraded within 2 days,which means that the sensor is degraded.In general,the sensor designed in this paper can realize the functions of displacement monitoring and controllable degradation,and has the potential as an implantable medical device.