Dr. Franz Irlinger
Technische Universität München
Institute for Micro Technology and Medical Device Technology

Prof. Dr. Tim Lüth
Technische Universität München
Institute for Micro Technology and Medical Device Technology

Prof. Frank Talke
University of California, San Diego
Center for Memory and Recording Research

The Talke Lab at UC San Diego is developing a novel implantable intra-ocular pressure (IOP) sensor for glaucoma research. The sensor can be integrated with an intraocular lens and surgically inserted in the eye through cataract surgery. The technology allows monitoring of IOP on a regular basis at the convenience of the patients’ home and would be a major landmark advance in ophthalmology. The sensor is a MEMS device, based on the formation and read-out of interference fringes developing between the sensor base and a deformable membrane on the top of the sensor. For implantation in the eye, the size of the sensor must be reduced to the sub-mm range, and bio-compatibility must be established. During the next stage of the project, the sensor will be miniaturized and integrated to an intraocular lens to form a function-augmented IOL. In-vivo tests will be undertaken after miniaturization and biocompatibility are accomplished.

Final report:

A miniaturized optical pressure sensor has been developed at CMRR/UCSD in Professor Talke’s laboratory for measuring the intra ocular pressure in the eye of glaucoma patients. The sensor consists of a small chamber (800 µm in diameter), closed off with a SiNi membrane. Light rays reflected from the top surface of the sensor membrane and the bottom surface of the sensor cavity form interference fringes that can be used to determine the intraocular pressure in the eye.

As part of a joint UCSD/TUM research project funded by BaCaTeC, a portable handheld reader was designed and built to capture the interference fringe pattern of the sensor. The handheld reader unit (Fig. 1) consists of an objective lens, a beam splitter, a 635 nm LED light source, a 5nm band pass filter, and a camera. In vitro pressure measurements were obtained with the handheld reader. The reader has been merged with a smart phone for data acquisition and tests with life rabbits have been performed successfully. Further improvements of the reader and miniaturization of the reader have been implemented.

Alexander Kief, who participated in this project in San Diego, was able to complete his master thesis at the Chair MiMed at TUM with the support of BaCaTeC.