Engineering Design of an Expandable One-dimensional Photonic Crystal Slab Biosensor Array for Joint Detection of Multiple Tumor Markers

This paper proposed a SOI based optofluidic one-dimensional(1D) photonic crystal slab biosensor array structure for multiple tumor markers detection. The array consists of multiple expandable sensing branches, each is composed of a nanobeam resonator transducer with excellent detection limit, a filter with low sidelobe jitter and a microfluidics roof. Using the 3D FDTD method, a 1D photonic crystal slot nanobeam resonator transducer consisting of a circular hole array linearly decreasing from the center to both ends was obtained. Under the influence of absorption loss of biological solution, the transducer works in the communication E-band, with the Q value up to 10487, refractive index sensitivity of 355 nm/RIU, and refractive index detection limit of 2.61×10 ^-5 RIU, corresponding to the detection of fg/mL carcinoembryonic antigen, which can be directly used for the detection of tumor marker under the capture of antibody probes in microfluidics chip. By optimizing the apertures on both sides of 1D photonic crystals with a taper shape, a cutoff filter with low sidelobe jitter can effectively filter out the high-order resonant peaks of the transducer, forming a large free spectral range. More importantly, the aforementioned sensing branch can be extended into arrays based on the frequency band effect of photonic crystals. This paper provided the expansion method and examples to verify that the extended branches have equally excellent detection performance, and analyzed the reasons why the sensing array has high MEMS preparation robustness. The array structure provides a good choice for label free point-of-care detection of multiple tumor markers.