Miniaturized LED light source with an excitation filter for fluorescent imaging

In this study, we developed a miniaturized InGaN blue μLED-based excitation source intended for an implantable lens-less brain imaging system. To enhance its implantability, the μLED was thinned further through the laser lift-off process. A filtering component comprising a short-pass interference filter and a low-NA fiber optic plate (FOP), was loaded onto the μLED. The addition of an interference filter reduced normal incident green-end band emissions from the μLED by two orders of magnitude. The application of FOP enables the resolution of the angle-dependent problem of the interference filter. Further, a fluorescent imaging experiment was carried out on the proposed excitation source. The proposed device produced bright fluorescence images that are sufficient for implantable in vivo application. The thickness of the proposed excitation device was 180 μm, making it suitable for implantable brain fluorescent imaging applications.