Needle-Type Imager Sensor With Band-Pass Composite Emission Filter and Parallel Fiber-Coupled Laser Excitation

This paper presents an implantable fluorescence system with a composite emission filter and fiber-coupled laser excitation. The composite structure of the short-pass interference filter and absorption filters exhibited a band-pass spectrum between 510 and 570 nm, which is close to green fluorescent protein (GFP) emission. A high-quality excitation light was achieved by utilizing a blue laser through a low-numerical-aperture optical fiber. This coupling method is beneficial in delivering a narrow spectrum and controllable irradiation light in a specific area to minimize auto-fluorescence from the tissue. The fabricated lensless system performance is experimentally validated by imaging emission. The proposed device is capable of perceiving fluorescence emission from microspheres and GFP noticeably.