Development of a neural probe integrated with high-efficiency MicroLEDs for in vivo application

A neural probe with six micro-light-emitting diodes (MicroLEDs) and 15 neural electrodes was fabricated for optogenetic application. Local field potentials, which provide information about the neural activity, were successfully recorded using the neural probe, indicating the effectiveness of the neural electrodes. The MicroLEDs on the probe exhibited highly consistent current-voltage characteristics and sufficient light output of 20 mW mm(-2) at 1 mA to manipulate neural activity. The light distribution in brain tissue was simulated to estimate the optical stimulation area and a number of optically stimulated neurons. The increase in LED temperature, i.e. Delta T, was investigated because high temperatures can damage brain tissue. A curve illustrating the relationship between Delta T and the wall-plug efficiency was derived. The wall-plug efficiency was increased 1.8 times by installing an Ag mirror on the back of a MicroLED. These results suggest that the MicroLED neural probe would significantly contribute to the development of neuroscience research-purposed optogenetic technology. (c) 2020 The Japan Society of Applied Physics