Department of Physics and Astronomy, Living Systems Institute, University of Exeter, Exeter, EX4 4QD, UK.
School of Biomedical Sciences, University of Plymouth, Plymouth, PL4 8AA, UK.
Small. 2022 Apr;18(15):e2107597. doi: 10.1002/smll.202107597. Epub 2022 Feb 26.
On-chip silicon microcavity sensors are advantageous for the detection of virus and biomolecules due to their compactness and the enhanced light-matter interaction with the analyte. While their theoretical sensitivity is at the single-molecule level, the fabrication of high quality (Q) factor silicon cavities and their integration with optical couplers remain as major hurdles in applications such as single virus detection. Here, label-free single virus detection using silicon photonic crystal random cavities is proposed and demonstrated. The sensor chips consist of free-standing silicon photonic crystal waveguides and do not require pre-fabricated defect cavities or optical couplers. Residual fabrication disorder results in Anderson-localized cavity modes which are excited by a free space beam. The Q ≈10 is sufficient for observing discrete step-changes in resonance wavelength for the binding of single adenoviruses (≈50 nm radius). The authors' findings point to future applications of CMOS-compatible silicon sensor chips supporting Anderson-localized modes that have detection capabilities at the level of single nanoparticles and molecules.
片上硅微腔传感器由于其紧凑性和与分析物的增强光物质相互作用，在病毒和生物分子的检测方面具有优势。虽然它们的理论灵敏度达到了单分子水平，但高质量 (Q) 因子硅腔的制造及其与光耦合器的集成仍然是单病毒检测等应用中的主要障碍。在这里，提出并演示了使用硅光子晶体随机腔的无标记单病毒检测。传感器芯片由独立的硅光子晶体波导组成，不需要预制缺陷腔或光耦合器。残余的制造无序导致安德森局域腔模式，这些模式由自由空间光束激发。Q ≈ 10 足以观察到单个腺病毒（≈50nm 半径）结合时共振波长的离散阶跃变化。作者的发现指出了具有单纳米粒子和分子检测能力的支持安德森局域模式的 CMOS 兼容硅传感器芯片的未来应用。
