In situ acoustomagnetic interrogation of a glaucoma valve with integrated wireless microactuator

This paper describes the design, fabrication and in situ evaluation of a system developed for interrogation of an actuator-integrated glaucoma valve. An implanted glaucoma valve facilitates drainage of aqueous humor from the eye to help lower intraocular pressure in patients with glaucoma. Here, a customized magnetoelastic actuator is integrated on the valve to limit the fibrosis and encapsulation of the valve that can otherwise lead to implant failure. The system described here excites the actuator magnetically and verifies the actuation by sensing the acoustic signals generated by the vibrating actuator. This work focuses on increasing the wireless range, reducing signal feedthrough, and establishing the clinical utility of the system. In vitro experiments performed with the system demonstrate a signal-to-noise ratio of =140. In situ experiments, performed with the actuator-integrated valves implanted in porcine eyes, achieve a signal to noise ratio of 3–6. These are the first recorded acoustic signatures through tissue from a magnetoelastic device in an implanted environment.