Exceptional point (EP) is referred to degeneracies in a non-Hermitian system where two or more eigenvalues and their corresponding eigenvectors coalesce. Recently there have been significantly increased interests in harnessing EPs to enhance responsivities and achieve ultrasensitive detections in optics, electronics and acoustics, although there are few similar studies focused on using surface acoustic wave (SAW) sensing technologies, probably due to its great technical challenges. Herein, we proposed a scheme for accessing EPs in an on-chip architecture consisted of coupled-SAW-resonators system, forming a passive parity-time (PT) symmetric system. We demonstrated that by tuning additional losses in one of resonators and regulating the system in the proximity of the EP, the sensor exhibited significantly enhanced responses. As an example, we present an EP-based SAW gas sensor, which showed a much-improved sensitivity compared to that of a conventional delay-line SAW sensor. The fundamental mechanisms behind this excellent sensing performance have been elucidated.

奇异点 （EP） 是指非厄米特系统中的简并性，其中两个或多个特征值及其相应的特征向量合并。最近，人们对利用 EP 来提高光学、电子和声学的响应度并实现超灵敏检测的兴趣显著增加，尽管很少有类似的研究专注于使用表面声波 （SAW） 传感技术，这可能是由于其巨大的技术挑战。在此，我们提出了一种在片上架构中访问 EP 的方案，该方案由耦合 SAW 谐振器系统组成，形成一个无源奇偶校验时间 （PT） 对称系统。我们证明，通过调整其中一个谐振器中的额外损耗并在 EP 附近调节系统，传感器表现出显着增强的响应。例如，我们提出了一种基于 EP 的 SAW 气体传感器，与传统的延迟线 SAW 传感器相比，它的灵敏度大大提高。这种出色的传感性能背后的基本机制已经阐明。