The Touch-tonometer Style Of Intraocular Pressure Measurement Based On Liquid-metal Soft Tactile Sensors

Glaucoma is the first irreversible blindness in the world.The occurrence of neurological damage caused by Glaucoma can not be recovered forever.Intraocular pressure(IOP)measurement can provide an important reference for preventation from glaucoma and the damage of high intraocular pressure to glaucoma patients.In the field of medicine,ophthalmologists are used to touching and pressing the closed eyelid with finger,feeling the pressure of intraocular pressure through the tactile feedback of the finger.Flexible tactile sensors can perfectly adapt to the complex 3D structure of the physical surface,which plays an important role as information collection front end in wearable devices,smart prosthetic limbs,biomedical fields,etc.In order to measure IOP in convenience and without injury,the touch tonometer is studied by combining the advantage of flexible tactile sensor.The fallowing researchs has been included:1.Combined the demands of IOP measurement with the advantages of tactile sensing,the whole touch-tonometer scheme of IOP measurement with soft tactile sensor is proposed,including the analysis of measurement principle and overall design of measurement system.2.A flexible tactile arrayed sensor based on Ecoflex(aliphatic aromatic random copolyester)and liquid metal(Egain alloy)was designed and made,according to the new demands of IOP measurement.It consists of liquid metal as electrodes and dielectric layer between the upper and lower electrode layers.The Mooney-Rivilin(MR)deformation parameters of Ecoflex are obtained for simulation by using the MR mechanical model.Then,the finite element simulation of the sensor under static pressure with the electromechanical coupling field was carried out by COMSOL software.Afterwards,the relation curve of capacitance-pressure is obtained.Based on the resistance-capacitance change mechanism of sensor under stress,a pressure measurement method of liquid metal array sensor is proposed.3.According to the design of measurement system and the demands of measurement,PCAP01 chip was selected as the main chip to completed the corresponding circuit module setting,including channel selection module,timing module,digital to capacitance conversion module.After PCB board was drawn and made,the software of the measurement system is completed,including the control of the main chip,the the upper computer interface for parameter configuration and data acquisition.At last,a reconstructed image of acquired data was made using Matlab.4.The measurement system and sensor under pressure were calibrated respectively with experiments.The scanning measurement experiment of sensor is carried out to verify the function of the whole touch-tonometer system.Then,the pressure identification method of liquid metal array sensor is verified.Finally,an IOP measurement experiment was carried out on the artificial eye using the touch-tonometer system,whose results reached the expected measurement requirements and verified the feasibility of the touch-tonometer IOP measurement scheme.