Fig. 1: Design and modelling of μLED array systems for optogenetic stimulation of the mouse cortical surface.
From: Chronically implantable μLED arrays for optogenetic cortical surface stimulation in mice
a Photograph of the fabricated side of unpackaged μLED array, highlighting ball-grade array (BGA) interconnection pads. b Sapphire (emitting) side of μLED array showing different illumination patterns and software-adjustable brightness. c Photograph of μLED array integrated to a flexible, lightweight package for chronic implantation. d Photograph of a mouse with a device chronically implanted over the auditory cortex (left). 3D model of μLED array over mouse auditory cortex (right); the 1 mW mm−2 level is shown given a single μLED illuminating a cortical surface irradiance of 10 mW mm−2; illustration produced using50,51. e Modelled optical profile of light propagation from a single illuminated μLED; irradiance levels are the same as (d). Model reflects chronic implantation with 150 μm sapphire and 15 μm parylene-C (PaC). f Irradiance-current (L-I) characteristic at the μLED surface and cortical surface (mean and standard deviation for n = 10 μLEDs). g Schematic and photograph of rigid device for acute experimentation; zoom shows gold ball-wedge wire bonds for interconnection and μLED addressing. h Schematic of chronically implantable device packaging and photograph of side-profile; bottom image shows the thermosonic flip-chip bonding process used for highly compact interconnection.
