Toward low-noise on-chip plasmonic three-dimensional biological cell imaging

Enhancing accessibility to affordable and efficient cell imaging tools has been a longstanding worldwide objective for rapid disease detection and diagnosis. We present an innovative approach to this goal, introducing a compact, portable, and user-friendly three-dimensional (3D) cell imaging platform leveraging silicon photonics and the surface plasmon coupled emission (SPCE) phenomenon. Central to our method is a specially designed slide that incorporates a fundamental SPCE structure seamlessly integrated with a silicon nitride (SiN) waveguide. We introduce a grooved array on the slide to couple light into the waveguide, interfacing with a broadband light source. This source is employed to excite fluorescently labeled cells. The excitation is achieved using edge coupling through the SiN waveguide, directing the excitation light to the specimen placed on the SPCE platform. This integrated architecture eliminates the necessity for an additional filter to extract the required light for fluorophore excitation while enabling precise excitation of labeled cells. Following the fluorophore excitation, the emitted SPCE signals are captured and subjected to analysis. We have developed an imaging algorithm based on the emitted light patterns, which we comprehensively detail through theoretical demonstration. This algorithm has the remarkable capability of achieving 3D cell imaging. This fusion of optics and computational techniques can significantly impact the domain of cell imaging by enabling the development of easily accessible and portable point-of-care (POC) imaging tools.