Abstract: A light source assembly includes a first annular reflector, a second annular reflector and a plurality of first light source modules. The first annular reflector has a first reflective surface. The second annular reflector is coaxial with the first annular reflector. A radius of the first annular reflector is greater than that of the second annular reflector. The second annular reflector has a second reflective surface facing the first reflective surface. The first light source modules take a central axis of the first annular reflector as a center and annularly arranged around the center. The first light source modules provide first beams to the first reflective surface, which reflects the first beams to the second reflective surface. The second reflective surface reflects the first beams and makes the first beams emit along a direction parallel to a central axis of the second annular reflector. A projection device is also provided.

Abstract: Disclosed herein is an implantable electrical stimulator which includes two stimulating electrodes, a system-on-chip and an inductive coil. The system-on-chip can apply electric stimulation to the dorsal root ganglion via the stimulating electrodes. An external power supply can wirelessly charge the system-on-chip through the inductive coil.