Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA.
Langmuir. 2013 Jun 11;29(23):7118-24. doi: 10.1021/la3034676. Epub 2013 May 28.
The emerging fields of nanomotors and optomechanics are based on the harnessing of light to generate force. However, our ability to detect small surface stresses is limited by temperature drift, environmental noise, and low-frequency flicker electronic noise. To address these limitations, we functionalized microfabricated silicon cantilevers with an azo dye, silane-based self-assembled monolayer and modulated the surface stress by exciting the optical switch with a 405-nm laser. Atomic force microscopy, contact angle analysis, ellipsometry, and X-ray photoelectron spectroscopy verified successful assembly of molecules on the cantilever. Ultraviolet and visible spectra demonstrate optical switching of the synthesized molecule in solution. By turning the laser on and off at a specific rate (e.g., 1 Hz), the cantilever deflection can be measured via Fourier techniques, thus separating the signal of interest from the noise. This technique empowers the design of highly sensitive surface stress measurements.
新兴的纳米马达和光机械学领域基于利用光来产生力。然而，我们检测小表面应力的能力受到温度漂移、环境噪声和低频闪烁电子噪声的限制。为了解决这些限制，我们用偶氮染料、硅烷基自组装单层对微加工硅悬臂梁进行功能化，并通过用 405nm 激光激发光学开关来调制表面应力。原子力显微镜、接触角分析、椭圆偏振和 X 射线光电子能谱证实了分子在悬臂梁上的成功组装。紫外和可见光谱证明了合成分子在溶液中的光学开关。通过以特定的速率（例如 1Hz）打开和关闭激光，可以通过傅里叶技术测量悬臂梁的挠度，从而将感兴趣的信号与噪声分离。这项技术使设计高灵敏度的表面应力测量成为可能。
