An integrated μLED optrode for optogenetic stimulation and electrical recording.

In this letter, we developed an integrated neural probe prototype for optogenetic stimulation by microscale light-emitting diode (μLED) and simultaneous recording of neural activities with microelectrodes on a single-polyimide platform. Optogenetics stimulates in vivo neural circuits with high-cellular specificity achieved by genetic targeting and precise temporal resolution by interaction of light-gated ion channels with optical beam. In our newly developed optrode probe, during optogenetic stimulation of neurons, continuous sensing of neuronal activities in vicinity of the activation site can provide feedback to stimulation or examine local responses in signal pathways. In the device, focusing the light from the μLED was achieved with an integrated photo-polymerized lens. The efficacy of the optrode for cortical stimulation and recording was tested on mice visual cortex neurons expressing channelrhodopsin-2. Stimulation intensity and frequency-dependent spiking activities of visual cortex were recorded. Our device has shown advantages over fiber-coupled laser-based optrode in terms of closed-loop integration, single-implant compactness and lower electrical power requirements, which would be clinically applicable for future prosthetic applications in personalized medicine.