Research toward photonic biosensors for point-of-care applications and personalized medicine is driven by the need for high-sensitivity, low-cost, and reliable technology. Among the most sensitive modalities, interferometry offers particularly high performance, but typically lacks the required operational simplicity and robustness. Here, we introduce a common-path interferometric sensor based on guided-mode resonances to combine high performance with inherent stability. The sensor exploits the simultaneous excitation of two orthogonally polarized modes, and detects the relative phase change caused by biomolecular binding on the sensor surface. The wide dynamic range of the sensor, which is essential for fabrication and angle tolerance, as well as versatility, is controlled by integrating multiple, tuned structures in the field of view. This approach circumvents the trade-off between sensitivity and dynamic range, typical of other phase-sensitive modalities, without increasing complexity. Our sensor enables the challenging label-free detection of procalcitonin, a small protein (13 kDa) and biomarker for infection, at the clinically relevant concentration of 1 pg mL⁻¹, with a signal-to-noise ratio of 35. This result indicates the utility for an exemplary application in antibiotic guidance, and opens possibilities for detecting further clinically or environmentally relevant small molecules with an intrinsically simple and robust sensing modality.

对高灵敏度，低成本和可靠技术的需求推动了针对即时医疗应用和个性化医学的光子生物传感器的研究。在最敏感的方式中，干涉测量法可提供特别高的性能，但通常缺乏所需的操作简便性和鲁棒性。在这里，我们介绍一种基于引导模式共振的共径干涉传感器，以将高性能与固有稳定性相结合。传感器利用两个正交极化模式的同时激发，并检测由传感器表面上生物分子结合引起的相对相变。传感器的宽动态范围对于制造和角度公差以及多功能性至关重要，可通过在视场中集成多个调谐结构来控制。这种方法避免了灵敏度和动态范围之间的折衷，这是其他对相位敏感的模式所特有的，而不会增加复杂性。我们的传感器能​​够以临床相关浓度1 pg mL进行具有挑战性的无标记检测降钙素原，一种小蛋白（13 kDa）和感染生物标志物^-1，信噪比为35。该结果表明该方法可用于抗生素指导中的示例性应用，并开辟了以本质上简单而强大的传感方式检测更多临床或环境相关小分子的可能性。