Instituto de Microelectrónica de Madrid, CSIC, Isaac Newton 8 (PTM), Tres Cantos, 28760 Madrid, Spain.
ACS Nano. 2011 Jun 28;5(6):4269-75. doi: 10.1021/nn200623c. Epub 2011 May 16.
The detection back-action phenomenon has received little attention in physical, chemical, and biological sensors based on nanomechanical systems. We show that this effect is very significant in ultrathin bimetallic cantilevers, in which the laser beam that probes the picometer scale vibration largely modifies the resonant frequencies of the system. The light back-action effect is nonlinear, and some resonant frequencies can even be reduced to a half with laser power intensities of 2 mW. We demonstrate that this effect arises from the stress and strain generated by the laser heating. The experiments are explained by two-dimensional nonlinear elasticity theory and supported by finite element simulations. The found phenomenology is intimately connected to the old unsolved problem about the effect of surface stress on the resonance frequency of singly clamped beams. The results indicate that to achieve the ultimate detection limits with nanomechanical resonators one must consider the uncertainty due to the detection back-action.
基于纳米机械系统的物理、化学和生物传感器中，对检测反向作用现象的关注较少。我们表明，在超薄的双金属悬臂梁中，探测皮米级振动的激光束极大地改变了系统的共振频率，这种效应非常显著。光反向作用效应是非线性的，甚至在激光功率强度为 2 mW 时，某些共振频率甚至可以降低到一半。我们证明，这种效应是由激光加热产生的应力和应变引起的。实验由二维非线性弹性理论解释，并通过有限元模拟得到支持。所发现的现象与关于表面应力对单夹梁共振频率影响的旧未解决问题密切相关。结果表明，为了使用纳米机械谐振器达到极限检测极限，必须考虑检测反向作用的不确定性。
