LAUSR

Neural stimulation with infrared radiation has been explored for brain tissue, peripheral nerves, and cranial nerves including the auditory nerve. Initial experiments were conducted at wavelengths between λ = 1,850 and λ = 2,140 nm and the radiant energy was delivered with square pulses. Water absorption of the infrared radiation at λ = 1,860 nm is similar to absorption at wavelengths between λ = 1,310 and λ = 1,600 nm, which are in the radiation wavelength range used for the communication industry. Technology for those wavelengths has already been developed and miniaturized and is readily available. The possibility of the infrared light to evoke compound action potentials (CAP) in the cochlea at λ = 1,375, λ = 1,460, and λ = 1,550 nm was explored and compared to that of λ = 1,860 nm in guinea pigs. Furthermore, rise and fall times of the 100 μs long pulses were changed and four basic pulse shapes (square, triangular, ramp-up, and ramp-down) were explored in their ability to evoke a CAP. In animals with pure tone threshold averages (PTAs) above 70 dB SPL, the results show that the favorable wavelength is λ = 1,460 nm to reach threshold for stimulation and λ = 1,375 nm or λ = 1,460 nm for obtaining maximum amplitude. The most favorable pulse shape is either ramp-up or triangular.