Engineers from the Fraunhofer Institute in Germany developed an implant for continuous intraocular pressure monitoring, primarily for patients suffering from glaucoma:
In future, a sensor developed by researchers at the Fraunhofer Institute for Microelectric Circuits and Systems IMS in Duisburg will obviate the need for constant visits to the physician by such patients. “We integrate the 2.5 by 2.6 millimeter sensor in the artificial lens,” says Thomas van den Boom, group manager for biohybrid systems at the IMS. “This doesn’t impair the patient’s vision.” The top and bottom of the sensor are formed by electrodes; the top electrode is flexible, in contrast to its rigid counterpart on the bottom of the sensor. When the intraocular pressure increases, the top electrode is pushed in, reducing the distance between the top and bottom of the sensor and thus increasing the capacitance. Using a tiny antenna, the implant then sends the pressure data to a reader that is fitted into the frame of a pair of spectacles. The patient can view the results on an auxiliary device and determine whether the pressure has reached a critical level. An antenna in the spectacle frame supplies the sensor with the required energy via an electromagnetic field. “The power consumption of the sensor must be kept to an absolute minimum,” explains van den Boom. “All unused components are put in a kind of standby mode and only activated when needed.”
The permanent eye implant is currently undergoing clinical trials and could come into general use in two to three years’ time. But the sensor is not only suitable for use in the eye: When implanted in blood vessels in the thigh or the upper arm it can also help patients with chronic hypertension.