Liane Rheinschmitt

Progress in the Development of the Artificial Accommodation System

Due to presbyopia or the treatment of cataract, the ability of the human eye to adapt its refractive power to objects situated in varying distances gets lost. Cataract is treated in a standard surgery. After extraction of the opaque human lens an artificial intraocular lens (IOL) is being implanted, which up to now does not allow to restore the accommodation ability like the one of a young person. Currently no method is available which enables sufficient long term amplitude of accommodation. Therefore the Artificial Accommodation System is in development at the Forschungszentrum Karlsruhe GmbH and the Department of Ophthalmology of the University of Rostock. This fully integrated mechatronic system is composed of a sensor system which acquires the actual accommodation demand, an active optical system with refractive power adjustable by an actuator, an energy supply for autonomous operation and a control unit. One major goal is to integrate all subsystems into an IOL sized, fully implantable device.

Robust intraocular acquisition of the accommodation demand using eyeball movements

The Artificial Accommodation System is a mechatronic lens implant that will restore the ability of the human eye to accommodate. Therefore, the accommodation demand has to be acquired. One possibility is to measure the vergence angle of the eyeballs in reference to an external field. Using the earth magnetic field as reference the proof of this measuring principle was possible. Still there are drawbacks like high responsivity to interferences and limitations of the measuring range. The new approach is to use the gravity field as reference and thus reduce the responsivity to interferences. The measuring range can be expanded by combining both sensing principles.

Investigation of the use of Solderjet Bumping for joining the thinwalled glass package of a complex mechatronic lens implant

The Artificial Accommodation System is a lens implant that shall restore the accommodation ability of the eye. This complex mechatronic micro system has to be encapsulated by a transparent hermetic package that also permits electromagnetic transfer of energy and data. Moreover, the production process of the package must not apply thermal stress to the internal components. This paper introduces an approach to build a glass package consisting of two glass parts manufactured by ultrasonic grinding. In order to join both parts, Solderjet Bumping is used. During this laser-based process single bumps of metal solder can be placed in order to connect the assembly parts. The hermeticity of the thereby produced glass packages is tested using helium leak tests. Furthermore, the influence of the metal ring on the power transfer efficiency is measured.

Low temperature production process for hermetic transparent implant packages

In order to produce a hermetic transparent package, two glass parts are manufactured using ultrasonic grinding. These parts are joined adhesively. Since polymers are not hermetic, water can diffuse through the adhesive and harm the internal components. Therefore, the bond seam is coated by sputtering a hermetic material onto the surface of the adhesive and the neighbouring areas of the glass parts. Different samples are produced using titanium coating and SiO2 coating. In order to determine the hermeticity of the produced packages, helium leak tests are used.