Concave 2D Ring Array Transducer for Ultrasound Visual Stimulation of the Brain

Restoration of vision of blind people has been successful by implanting electrode arrays into the eyes near the retina. However, this method is invasive and may have a chance to cause surgical complications. Recently, both in vitro and in vivo studies show that ultrasound can be used to stimulate cells on the retina and subsequently stimulate the corresponding parts of the neurons in the brain to produce a perception of vision for certain blind people. Unlike implant of electrodes, ultrasound is non-invasive. In this paper, we studied a concave two-dimensional (2D) ring array transducer to produce high-resolution ultrasound images of objects on the retina to stimulate the brain for a perception of vision. The advantages of using concave 2D ring array transducer (20-MHz frequency or 0.075-mm wavelength, 14-mm outer diameter, 9-mm inner diameter, 18-mm curvature, a pitch of 4 wavelengths, and about 1000 elements) are that the array can fit the eyeballs better in shape, can reduce the number of transducer elements needed due to its curvature, and can avoid the heating to the lens of the eye due to the high ultrasound attenuation of the lens tissues. The high ultrasound frequency used allows a high full-width-at-half-maximum (FWHM) resolution about 0.147 mm.