Crecea Vasilica, Oldenburg Amy L, Liang Xing, Ralston Tyler S, Boppart Stephen A
Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green St., Urbana, IL 61801, USA.
Opt Express. 2009 Dec 7;17(25):23114-22. doi: 10.1364/OE.17.023114.
The availability of a real-time non-destructive modality to interrogate the mechanical properties of viscoelastic materials would facilitate many new investigations. We introduce a new optical method for measuring elastic properties of samples which employs magnetite nanoparticles as perturbative agents. Magnetic nanoparticles distributed in silicone-based samples are displaced upon probing with a small external magnetic field gradient and depth-resolved optical coherence phase shifts allow for the tracking of scatterers in the sample with nanometer-scale sensitivity. The scatterers undergo underdamped oscillations when the magnetic field is applied step-wise, allowing for the measurement of the natural frequencies of oscillation of the samples. Validation of the measurements is accomplished using a commercial indentation apparatus to determine the elastic moduli of the samples. This real-time non-destructive technique constitutes a novel way of probing the natural frequencies of viscoelastic materials in which magnetic nanoparticles can be introduced.
一种用于探测粘弹性材料力学性能的实时无损方法的出现将推动许多新的研究。我们引入了一种新的光学方法来测量样品的弹性特性，该方法采用磁铁矿纳米颗粒作为微扰剂。分布在硅基样品中的磁性纳米颗粒在受到小的外部磁场梯度探测时会发生位移，并且深度分辨的光学相干相移允许以纳米级灵敏度跟踪样品中的散射体。当磁场以阶梯方式施加时，散射体会经历欠阻尼振荡，从而能够测量样品的固有振荡频率。使用商业压痕设备来确定样品的弹性模量，从而完成测量的验证。这种实时无损技术构成了一种探测可引入磁性纳米颗粒的粘弹性材料固有频率的新方法。
