A 120 dB Dynamic range logarithmic multispectral imager for near-infrared fluorescence image-guided surgery

Despite tremendous developments in preoperative imaging that have enabled physicians to identify cancers with remarkable precision, limited options for intraoperative imaging have left many surgeons ill-equipped to locate tumors in the operating room. Near-infrared fluorescence image-guided surgery has offered to use near-infrared fluorescent dyes and near-infrared sensitive cameras to highlight diseased tissue, but state-of-the-art imaging systems have been unable to provide both the single sensor architecture and the high dynamic range required to facilitate precise surgical procedures under operating room illumination. In seeking a solution, we have monolithically integrated an array of forward-biased photodiodes and an array of interference filters to provide a logarithmic photoresponse across four spectral channels. The resulting single-chip snapshot multispectral imaging system provides an instantaneous dynamic range of >120 dB and a maximum signal-to-noise ratio of ~56 dB across three color channels and one near-infrared channel. Capable of detecting less than 50 nM of the clinically-relevant fluorescent dye indocyanine green, this image sensor offers the high performance required for real-world surgical application.