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Laser microperforation of poly(dimethylsiloxane) (PDMS) for the durable fixation of a retina implant


Denney, P. ; Laser Institute of America -LIA-:
Laser Materials Processing Conference 1999. Proceedings
Orlando, Fla.: LIA, 1999 (LIA 87)
ISBN: 0-912035-60-9
International Congress on Applications of Lasers and Electro Optics (ICALEO) <1999, San Diego/Calif.>
Laser Materials Processing Conference <1999, San Diego/Calif.>
Fraunhofer ILT ()
excimer laser; microperforation; biomaterial; siloxane polymer; Retina-Implant; surface modification

Patients who are suffering from Retinitis pigmentosa shall be given back a sight impression by an implant which stimulates the retinal ganglion cells by electrical pulses. The implant is placed on top of- the retina and must be fixed permanently. This is achieved by proliferation of' retinal glia cells into microperforated regions of the implant. The stimulator electronics is embedded into crosslinked poly(dimethylsiloxane) (PDMS). The haptic area perforated by a laser ablation process using excimer laser radiation (lambda = 193 nm) to produce conical holes of 50 mu m average diameter in a screen of 100 mu m. To prevent potentially toxic recondensation products (debris) from the ablation process, the PDMS is temporarily coated with poly(vinylalcohol) (PVA). After laser treatment the coating with debris is washed off. Subsequently the PDMS-surface is chemically modified by plasma treatment and graft- copolymerization, which facilitates Mueller-cells to grow into the perforation holes. Cell proliferation is proven in In vitro and in vivo experiments. The sensor part is also laser treated. To optimize the stimulation of ganglion cells their close contact to the electrodes is essential. Therefore the electrodes are exposed by scanning the area with an excimer laser beam. This process preserves the hydrophobicity of the PDMS, which prevents other cells from disturbing the contact.