Research On 3D Printing Process And Frequency Response Characteristics Of Middle Ear Ossicular Chain

Hearing loss is a disease that affects human daily life.For patients with conductive hearing loss,hearing can only be restored through ossicular chain reconstruction surgery.Due to the fine structure,different individual shapes,and complex types of lesions of the ossicles that transmit sound waves,only prostheses with similar shape,length,and angle to the ossicles can be selected for shaping and implantation during surgery.The above process not only increases the difficulty of operation and surgical time,but also fails to consider the impact of different ossicular material reconstruction on the sound transmission of the ossicular chain.In addition,human temporal bones are often used for experiments,but fresh preparations are not easily obtainable and their performance varies over time and individuals.Therefore,it is necessary to design a reproducible environment for the evaluation of ossicular implants.To address the above problems,this thesis proposes to convert the temporal bone CT image data into a 3D model of the auditory bone,establish a finite element model of the auditory bone,predict the sound transmission performance by replacing the auditory bone material,design and manufacture an in vitro auditory bone chain vibration detection model by combining 3D printing technology,and conduct frequency response characteristics analysis.The details of the study are as follows:Firstly,titanium alloy TC4,stainless steel 316L,and composite material HA/PCL were selected as ossicular materials for exploration.Using 3D printing technology(SLM,FDM)to shape the sample,select corresponding process parameters based on its performance indicators,and then conduct mechanical properties(hardness,friction and wear,corrosion,stretching,density)and biocompatibility(cell proliferation,live death staining determination)tests,and compare and analyze with the requirements of the fake preparation.The results showed that the three materials basically met the mechanical performance requirements,and only a small number of dead cells were observed by cell staining,indicating good biocompatibility.Secondly,by converting temporal bone CT image data into an ossicular model,a finite element model was established to verify its reliability and perform modal analysis on its structure.By combining 3D printing to create an anatomical based in vitro middle ear model,the effects of tympanic membrane material,presence/absence of ligaments,and opening/closing of the middle ear cavity on hearing were analyzed under in vitro conditions.Laser vibration measurement and pure tone testing were used to validate the in vitro vibration model of the ossicular chain.The results indicate that using 3D printing technology combined with silicone rubber molding can establish an artificial model of the ossicular chain,replicate the anatomical shape of the basic components of the middle ear,and assemble it into a functional middle ear model.Finally,based on the above finite element model,investigate the frequency response effect of a single auditory ossicle(malleus,incus,stapes)after replacing the aforementioned materials.The results showed that titanium alloy TC4 and stainless steel 316L were used to replace the malleus and incus,resulting in hearing gain in the low frequency range.HA/PCL was used to replace the malleus and incus,resulting in a slight decrease in hearing in the low frequency range.Other frequency ranges were in line with normal ears.In terms of stapes replacement,all three materials showed hearing deterioration in the low and medium frequency bands,with only HA/PCL showing similar hearing to normal ears in the high frequency band.On this basis,an exploration was conducted on the simultaneous replacement of three auditory ossicles,and laser vibration measurement experiments were used to verify it.The trend of the measured data was consistent with the finite element simulation results.In the combination of ossicular chain materials,only TC4-TC4-HA/PCL had a hearing change within ± 3 d B,and it was found that under the fixation of stapes material,the hearing difference produced by different combinations of malleus and incus was very small.This thesis has 65 pictures,20 tables and 96 references.