眼角膜超声测厚及眼压测量复合传感器设计

眼角膜厚度和眼压是眼球的两个重要生理参量,是诊断屈光不正、青光眼等眼科疾病的重要指标.新型复合传感器能一次性完成两个参量的测量.使用这种传感器,可以提高眼科医学诊断的便利性,同时可以根据角膜厚度修正眼压值.通过超声传感器和使用电磁驱动的压力控制系统相结合,实现两种测量的同步完成.超声传感器采用PZT系列压电复合材料,角膜厚度采用超声波脉冲回波法测量.电磁压力控制根据眼压测量的需求,通过计算得到电磁驱动系统的结构参数和电磁参数.由实验测量结果可知,角膜厚度测量精度在±10μm范围内;电磁压力控制系统的压力范围为0~0.490 N,精度为0.0006 N.该复合传感器测量精度和范围符合传统角膜测厚和眼压计的标准,为二合一眼科仪器研制打下基础.

Design of composite sensor for ultrasound corneal thickness and intraocular pressure measurement

Corneal thickness and intraocular pressure ( IOP ) are both the significant physiological parameters of the eyeball,and have great influence on the diagnosis of refractive errors, glaucoma and other eye diseases. The new kind of composite sensor could achieve a simultaneous measurement of the two parameters. The use of this sensor, on the one hand could improve the convenience of ophthalmic diagnosis,on the other hand could correct IOP based on corneal thickness. To complete the two measurements synchronously,the ultrasonic sensor and the electromagnet-ic-driven pressure control system were combined. Ultrasonic sensor used piezoelectric composite materials,and cor-neal thickness was measured with the high frequency ultrasonic pulse-echo. The structural and electromagnetic con-trol parameters in the electromagnetic drive system were got by electromagnetic functions,the electromagnetic force was controlled according to the actual needs of IOP measuring. The experimental results showed that the accuracy of corneal thickness measurement was within ± 10 μm;in the electromagnetic pressure control system, the pressure range was 0~0.490 N,the accuracy 0.0006 N. The accuracy and range of the composite sensor were in line with the standard of traditional corneal thickness measurement and tonometer. This study laid the foundation for the fur-ther development of two-in-one measuring ophthalmic instruments.