Goßler, C.C.GoßlerBierbrauer, C.C.BierbrauerMoser, R.R.MoserKunzer, MichaelMichaelKunzerHolc, KatarzynaKatarzynaHolcPletschen, WilfriedWilfriedPletschenKöhler, KlausKlausKöhlerWagner, J.J.WagnerSchwaerzle, M.M.SchwaerzleRuther, P.P.RutherPaul, O.O.PaulNeef, J.J.NeefKeppeler, D.D.KeppelerHoch, G.G.HochMoser, T.T.MoserSchwarz, U.T.U.T.Schwarz2022-03-042022-03-042014https://publica.fraunhofer.de/handle/publica/23623210.1088/0022-3727/47/20/205401Currently available cochlear implants are based on electrical stimulation of the spiral ganglion neurons. Optical stimulation with arrays of micro-sized light-emitting diodes (µLEDs) promises to increase the number of distinguishable frequencies. Here, the development of a flexible GaN-based micro-LED array as an optical cochlear implant is reported for application in a mouse model. The fabrication of 15 µm thin and highly flexible devices is enabled by a laser-based layer transfer process of the GaN-LEDs from sapphire to a polyimide-on-silicon carrier wafer. The fabricated 50 × 50 µm(2) LEDs are contacted via conducting paths on both pand n-sides of the LEDs. Up to three separate channels could be addressed. The probes, composed of a linear array of the said µLEDs bonded to the flexible polyimide substrate, are peeled off the carrier wafer and attached to flexible printed circuit boards. Probes with four µLEDs and a width of 230 µm are successfully implanted in the mouse cochlea both in vitro and in vivo. The LEDs emit 60 µW at 1 mA after peel-off, corresponding to a radiant emittance of 6 mWmm(-2).encochlear implantsoptogeneticsmicro-LED arrayflexible substrate530journal article