Knittel Joachim, Swaim Jon D, McAuslan David L, Brawley George A, Bowen Warwick P
School of Mathematics and Physics, University of Queensland, St Lucia, QLD 4072, Australia.
Sci Rep. 2013 Oct 17;3:2974. doi: 10.1038/srep02974.
Whispering gallery mode biosensors allow selective unlabelled detection of single proteins and, combined with quantum limited sensitivity, the possibility for noninvasive real-time observation of motor molecule motion. However, to date technical noise sources, most particularly low frequency laser noise, have constrained such applications. Here we introduce a new technique for whispering gallery mode sensing based on direct detection of back-scattered light. This experimentally straightforward technique is immune to frequency noise in principle, and further, acts to suppress thermorefractive noise. We demonstrate 27 dB of frequency noise suppression, eliminating frequency noise as a source of sensitivity degradation and allowing an absolute frequency shift sensitivity of 76 kHz. Our results open a new pathway towards single molecule biophysics experiments and ultrasensitive biosensors.
回音壁模式生物传感器能够对单个蛋白质进行选择性的无标记检测,并且结合量子极限灵敏度,具备对运动分子运动进行非侵入式实时观测的可能性。然而,迄今为止,技术噪声源,尤其是低频激光噪声,限制了此类应用。在此,我们介绍一种基于背向散射光直接检测的回音壁模式传感新技术。这种实验上简单直接的技术原则上不受频率噪声影响,而且还能抑制热折射噪声。我们展示了27分贝的频率噪声抑制效果,消除了频率噪声作为灵敏度下降的一个来源,并实现了76千赫的绝对频移灵敏度。我们的结果为单分子生物物理实验和超灵敏生物传感器开辟了一条新途径。