Study On Intraocular Pressure Monitoring And Micro-drainage Technology For Glaucoma Treatment

Glaucoma is a disease caused by the continuous or intermittent elevation of intraocular pressure(IOP) over eyeball tolerance and then damaging optic nerve owing to undue aqueous humor. Current treatment methods for glaucoma cannot achieve a desired effect or even produce side-effects. Therefore, it is of great significance to glaucoma diagnosis and treatment by accurately monitoring intraocular pressure in real time for a long period of time. However, the current measurement and monitoring technology flaws in dimension, measuring accuracy, power consumption and intelligence could hardly meet the diagnosing and monitoring requirement for glaucoma patients. For this purpose, an implantable intelligent intraocular pressure monitoring and micro drainage system is proposed in this paper, regarding to the glaucoma therapy. The target IOP is set based on the damage extent of patient’s optic nerve and visual field. And it is essential for personalized and precise treatment that internal microelectronic system automatically controls the switch of micro-pump system to deliver drug or drainage the aqueous humor when IOP is beyond the set value after the target IOP is set based on the damage extent of patient’s optic nerve and visual field. The main contents and conclusions of this paper are as follows:Firstly, in view of the demand for glaucoma therapy, a summary of the structure and function of IOP monitoring and micro-drainage system is presented. The implantation systems are divided into IOP sensor, diversion control tube, processing circuit, wireless communication, power supply module and other parts. The specific working process of implantation systems is: implant the IOP monitoring devices into patient’s eyes and then is diverted to the sensitive area of IOP sensor and venaeciliares to realize the 24 hours real-time monitoring of IOP and aqueous humor drainage. After the IOP measurement value is amplified by the processing circuit, it will be transmitted to extraocular reception and monitoring system through wireless communication module where the patient and doctor can monitor the changes of intraocular pressure. The proposed device is helpful for doctors to conduct therapy accordingly in order to maintain the patient’s IOP in a safe and stable state.Secondly, a kind of thin film capacitor micro pressure sensor based on flexible electrode structure is proposed according to the analysis of research status of IOP sensor. The thin film capacitor micro pressure sensor is made through modeling, simulation as well as optimization and exploration of processing technique. Besides, the small scale and high sensitivity pressure detection is realized by establishing the test system. On one hand, the manufacturing processes and methods of micro/nano-structure of that sensor are studied and aim at the requirement of long time implanted in human body. The surface treatments and packaging processes are investigated to avoid the human body fluid influencing on the long-term stability of sensor. On the other hand, by combining the standard micro/nano machining technology with soft lithography, the chemical vapor deposition, sputtering and other methods are studied for surface processing and packaging the sensor. This kind of flexible electrode thin film capacitor micro pressure sensor with micro structure owns a simpler process flow and higher pressure sensitivity than the capacitive pressure sensor with cavity structure. What’s more, compared with the conventional electrodes deposition method, it’s not only more simple and easy to directly use the flexible conductive adhesive as electrode, but also bringing the advantages of low cost and high technical success ratio. The work of this paper provides a new idea for the research of flexible micro capacitance sensor.Furthermore, based on the investigation, analysis and selection of commercial devices, the commercial devices are modified with biological compatibility technology, given the demand of IOP sensor. The test results show that the pressure sensitivity, accuracy and power consumption of modified commercial devices basically meet the monitoring requirement of IOP. In addition, the package size of the sensor can be reduced, but the reliability needs to be further studied.Finally, by analyzing the driving principle of micro drainage device and comparing with existing devices and equipment, two driving principles are proposed for the subject of this paper: piezoelectric driving and electrochemical driving. The structure of micro drainage device is designed by analyzing the micro drainage device of aqueous humor so as to achieve the unidirectionality of drainage, which means the designed micro pump just needs to realize the one-way flow. Next, the material for preparing micro drainage device is selected and analyzed, in which the selected material needs to be in possessions of compatibility, stability, corrosion resistance and heat-resistant ability. Then, the structure of micro drainage device is processed with appropriate processing technique and the performance of micro drainage device is tested as well. At last, the capability for the micro drainage device to meet the conditions of the water in the room is verified by changing the voltage.