Im Projekt wurden neuar­tige Mikro-Elektro­den auf der Basis von High-Tech-Materia­lien zur räumlich und zeitlich hochauf­lö­sen­den elektri­schen Stimu­la­tion von neuro­na­lem Gewebe entwi­ckelt. Diese hochef­fi­zi­en­ten Elektro­den sollen in Zukunft in Retina­im­plan­ta­ten Anwen­dung finden und zu einer Verbes­se­rung der Sehleis­tung beitragen.

Es handelt sich um eine Koope­ra­tion der Hector Fellows Manfred Kappes, Karl Leo, Martin Wegener und Eberhart Zrenner sowie der HFA Postdok­to­ran­den Dr. Wadood Haq (Eberhard Karls Univer­si­tät Tübin­gen) und Dr. Franz Selzer (TU Dresden).

World­wide milli­ons of people suffer from blind­ness due to degene­ra­tion of the light sensi­tive photo­re­cep­tor cells of the retina. To date there are no thera­pies available to cure this progres­sive disease. However, promi­sing results for resto­ra­tion of vision have been achie­ved in clini­cal trials with electro­nic retinal implants [Zrenner et al., 2013]. Blind patients with heredi­tary retinal degene­ra­tion were enabled to experi­ence some visual sensa­ti­ons again: they locali­zed objects of daily life; some of them could even identify large letters.

This inter­di­sci­pli­nary project aims at optimi­zing the inter­face of electrode material and neuron in order to improve tempo­ral and spatial resolu­tion of retinal implants by bringing together experts in the field of ophthal­mo­logy and retinal implants, of novel electrode materi­als as well as of the synthe­sis and struc­tu­ring of such materi­als. The chall­enge on the one hand is the limited choice of electrode materi­als that are bio-compa­ti­ble and on the other hand the high density of diffe­rent neurons to be stimu­la­ted.
This optimiza­tion process will iterate through the loop of three steps:

1. Exper­tise in fabri­ca­tion of highly effici­ent electro­des (Prof. Leo & Dr. Selzer): To improve the spatial resolu­tion of the implant, the develo­p­ment of micro electro­des is planned. These electro­des will ideally allow the addres­sing of single or few retinal cells by electri­cal stimulation.

2. Fabri­ca­tion of conduc­tive 3D micros­truc­tures (Prof. Kappes & Prof. Wegener): Not only the size but also the topology and the electric conduc­ti­vity of electro­des have impact on the excita­tion of diffe­rent functional cell types of the retina as well as on selec­ti­vity and safety. Electrode arrays are being develo­ped that are suffi­ci­ently conduc­tive and that can be struc­tu­red into three-dimen­sio­nal archi­tec­tures by using laser lithography.

3. Exper­tise of ophthal­mo­logy and retinal implants (Prof. Zrenner & Dr. Haq): The effici­ency and safety of the develo­ped electro­des for neuro­nal stimu­la­tion will be inves­ti­ga­ted and evalua­ted in the ex-vivo retina of mouse models for retinal degeneration.

The inter­ac­tive feedback between the partners will allow conti­nuous impro­ve­ment of the electro­des. The final milestone of the project is to incor­po­rate the optimi­zed electro­des in an implant (demons­tra­tor) for impro­ved retinal stimulation.

Referen­ces:

[Zrenner et al., 2013] "Fight­ing Blind­ness with Microelec­tro­nics", Eberhart Zrenner, Science Trans­la­tio­nal Medicine 2013, Vol. 5, Issue 210, pp. 210ps16, DOI: 10.1126/scitranslmed.3007399