3D-Printed Optogenetic Device with a Recording-Channel-Embedded Waveguide

This paper presents an optogenetic device featuring a 3D-printed waveguide that integrates a recording wire within the waveguide itself. The recording channel is exposed at the tip of the waveguide, enabling direct neural signal monitoring at the exact site of light delivery. By placing the recording site precisely where optical stimulation occurs, the device reduces the spatial mismatch between the stimulated area and the recording location. The waveguide is coupled with four micrometer-sized light-emitting diodes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mu \text{LEDs})$</tex> on a 3D-printed substrate, and electrical connections are made using thin gold wires. We validate the device through electrical, optical, and electrochemical measurements.