Low-pressure treatment control of glaucoma using an electromagnetic valve in actuator with a piezoresistive pressure sensor

This paper concerns the control of intraocular pressure (IOP, eye pressure) for the treatment of glaucoma within a hundred pascal out of a total of a few thousand pascal by using an electromagnetic valve actuator and a pressure sensor. The proposed valve actuator is electromagnetically driven to change the area of the outlet by moving a membrane vertically, which is optimally designed to give the maximum pressure sensitivity over the applied voltage. The pressure sensor is piezoresistive type whose geometric parameters such as length and number of turns of the piezoresistor are optimally designed to give the maximum signal to noise ratio, which becomes critical in this low-pressure regime, in the case of constant voltage excitation and measurement. It is experimentally demonstrated that the pressure can be controlled below a 100 Pa resolution by using the proposed valve actuator and the pressure sensor.