Implantable wirelessly powered optoelectronic device for optogenetics

In vivo optogenetics provide special and powerful capabilities in regulation of neurons, research of neural circuits and even in treatment of brain diseases. However, conventional hardware for such studies tethers the experimental animals to remote light sources, power sources, or other functional modules, which imposes considerable physical constrains on natural behaviors and limits the range of the experiment. To enable flexible and convenient optogenetic manipulation of neural circuit with finite disruption of animal behavior, a wirelessly powered optoelectronic device, composing mainly of a radio frequency (RF) energy harvester and a high-performance GaN-based light-emitting diode (LED), is demonstrated and can be used to construct an implantable optrode for optogenetics. The wireless RF power signal is collected through an antenna and a two-stage voltage doubling rectifier circuit, and finally converted into high-amplitude DC voltage. Provided with 25-dBm RF power with a distance of 0.2 m, the RF energy harvesting and processing circuit can output a stable 2.81 V DC voltage and drive the designed GaN-based LED to work normally. After being successfully lit, the emission peak wavelength of the LED locates 455 nm and the output optical power density reaches 214.9 mW / mm2, which is fully capable of activating light-sensitive ion channel channelrhodopsin-2. The total area of the device is 3 mm × 3.2 mm, which is suitable for subdermal implantation.