Fig. 2: Design and structure of FIMOSS implant for long-term multisite optogenetic stimulation.

a, b Photographs of a FIMOSS implant that consists of a cuff optrode (MOSD II), interconnect, driver and antenna (scale bar = 5 mm); image of the front side of a FIMOSS implant placed near a coin (a), image of the reverse side of a FIMOSS implant (b). c Intraoperative photographs of a FIMOSS implant during the implantation surgery. (scale bar = 1 mm) Three parts of the FIMOSS implant were fixed at the designed positions: (i) MOSD II wrapped around the brachial plexus (C7 nerve as an example), (ii) the interconnect through an incision on the pectoralis major, (iii) the driver and antenna on the surface of the ipsilateral pectoral major. d A layered schematic illustration of FIMOSS implant. e The interface between the nerve and MOSD II. (scale bar = 500 μm) f–h Different stitching and fixation method (left, scale bar = 500 μm) and cross-section diagram (right, scale bar = 250 μm) of MOSD II adapted to nerves of different diameters. f The outer and inner suture eyelets were sacrificed and overlapped respectively to wrap around the nerve with a diameter of around 250 μm. g The outer suture eyelets were sacrificed while the inner eyelets were sutured to adapt to a nerve with diameter of 380 μm. h The outer suture eyelets were sutured to adapt to a nerve with a diameter of 600 μm.