Development Of Testing Device For Applanation Tonometer

With the continuous promotion and application of biomedical related technologies in the medical field,intraocular pressure detection technology has gradually entered the field of clinical ophthalmology and achieved good results.The design and research of intraocular pressure detection instruments have been continuously proposed by scholars.Applanation tonometer is the most commonly used type of special measuring instrument for the detection of intraocular pressure,and its measuring value is relatively accurate,and is widely used in ophthalmic clinics of hospitals at all levels.In order to ensure the accuracy and reliability of the pressure gauge,the operator needs to conduct the error test regularly.There is still a shortage of existing ophthalmograph verification ability,the technology is relatively backward,and the calibration standard is not unified,so the device that is used to check the accuracy of the examination of the ophthalmoscopy has been required,and the development of this device is of great significance to the clinical safety of the measurement of the accuracy of the eye pressure.In this paper,the Imber-Fick theory and the working principle of Goldmann tonometer is analyzed,and the working principle of the existing applanation tonometer detection device is discussed,and the measurement error of the simulation is carried out,and the measuring error of the device is carried out,and the measuring device of the pressure gauge is developed by using the micromechanical sensor.The research content and work of this paper mainly include the following parts:(1)Based on the biomechanical characteristics of cornea,the development of simulated human eyes is carried out.In this paper,the analysis of biomechanical properties of cornea,the finite element simulation of simulated cornea,and the comparison of the properties of existing materials in the laboratory,it is proposed that polydimethylsiloxane(PDMS)can be used as a polymer hyperelastic material to produce simulated cornea.The compression model and eyeball model for simulating cornea were designed and manufactured.In the eye model,the simulated cornea prepared was pressed together with the device through the gland structure to form a cavity of certain shape,which can be simulated in the eye pressure within the range of 0～70mm Hg,and the simulated intraocular pressure can properly adjust the intraocular pressure normally.However,due to the limited conditions,the measurement accuracy of the simulated human eye designed in this paper is not enough,and the reaction time of the IOP is too long,which cannot achieve the real-time and accurate detection of the tonometer.Therefore,the design scheme of the device that can directly detect the tonometer with the help of the micro force sensor is proposed.(2)The detection device of flattening tonometer was built with the help of micro force sensor.The device mainly includes three parts: hardware system of lower computer,software system of upper computer and mechanical device.Among them,the hardware system of the lower computer mainly includes power module,pressure detection unit,analog-digital conversion unit,data processing and display unit,communication unit and so on.The upper computer software mainly uses C# language to design,write and debug the operation program on Visual Studio software.The interface can realize the real-time dynamic display of the test value and real-time dynamic drawing of test values on the flatting tonometer,meanwhile,the test results can be selectively saved in Excel,so as to facilitate post-processing of data and other operations.(3)Using standard weight and SB-650 GAT(Goldmann leveling tonometer)provided by a company,the performance verification experiment of the device is designed.The experiment measured the device data response time about 2.2s for the first time in 0 ～ 10 g measurement range inner device sensitivity to 20 mg,the maximum error is 0.011,the biggest value for the standard deviation is 0.007,have can meet such as over-voltage alarm function,the test device which can realize PC during testing of the measurement data of real-time display and storage,and other functions,meet the design requirements of detection device.This device realizes the integration of the whole device,with the advantages of high accuracy of measured values,strong usability and simple operation,which can provide a feasible means for the measurement and detection of flattened intraocular pressure gauge,and has positive significance for ensuring the accuracy of clinical intraocular pressure.