Neural optical probe with monolithically integrated intensity-monitoring μLED and polymer waveguide for optogenetics

A neural optical probe that is monolithically integrated with a micro-light-emitting diode (mu LED), a micro-photodiode (mu PD), and a cyclo-olefin polymer (COP) waveguide is a novel optogenetic tool that can suppress the influence of heat while utilising the advantage of LED. Although a mu LED temperature increased by 0.3 degrees C at a light output of 100 mW/mm(2), heat did not spread to the optical stimulation area. The emission from the mu LED is propagated through a 2 mm long COP waveguide, suggesting that the mu LED placed on the outside of the brain can optically stimulate the deep region of brain tissue. Furthermore, it is successfully detected at the mu PD located close to the mu LED, which proved that the mu PD was effective to monitor the light output of the mu LED.