Xia Fangzhou, Yang Chen, Wang Yi, Youcef-Toumi Kamal, Reuter Christoph, Ivanov Tzvetan, Holz Mathias, Rangelow Ivo W
Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Nano analytik GmbH, Ehrenbergstraße 1, 98693 Ilmenau, Germany.
Nanomaterials (Basel). 2019 Jul 14;9(7):1013. doi: 10.3390/nano9071013.
Atomic force microscopy is a powerful topography imaging method used widely in nanoscale metrology and manipulation. A conventional Atomic Force Microscope (AFM) utilizes an optical lever system typically composed of a laser source, lenses and a four quadrant photodetector to amplify and measure the deflection of the cantilever probe. This optical method for deflection sensing limits the capability of AFM to obtaining images in transparent environments only. In addition, tapping mode imaging in liquid environments with transparent sample chamber can be difficult for laser-probe alignment due to multiple different refraction indices of materials. Spurious structure resonance can be excited from piezo actuator excitation. Photothermal actuation resolves the resonance confusion but makes optical setup more complicated. In this paper, we present the design and fabrication method of coated active scanning probes with piezoresistive deflection sensing, thermomechanical actuation and thin photoresist polymer surface coating. The newly developed probes are capable of conducting topography imaging in opaque liquids without the need of an optical system. The selected coating can withstand harsh chemical environments with high acidity (e.g., 35% sulfuric acid). The probes are operated in various opaque liquid environments with a custom designed AFM system to demonstrate the imaging performance. The development of coated active probes opens up possibilities for observing samples in their native environments.
原子力显微镜是一种在纳米级计量和操作中广泛使用的强大的形貌成像方法。传统的原子力显微镜（AFM）利用一个通常由激光源、透镜和四象限光电探测器组成的光学杠杆系统来放大和测量悬臂探针的偏转。这种用于偏转传感的光学方法限制了AFM仅在透明环境中获取图像的能力。此外，由于材料的多种不同折射率，在具有透明样品室的液体环境中进行轻敲模式成像时，激光探头对准可能会很困难。压电致动器激励可能会激发杂散结构共振。光热驱动解决了共振混淆问题，但使光学设置更加复杂。在本文中，我们展示了具有压阻式偏转传感、热机械驱动和薄光刻胶聚合物表面涂层的涂层有源扫描探针的设计和制造方法。新开发的探针能够在不透明液体中进行形貌成像，而无需光学系统。所选涂层能够承受高酸度的恶劣化学环境（例如，35%的硫酸）。这些探针通过定制设计的AFM系统在各种不透明液体环境中运行，以展示成像性能。涂层有源探针的开发为在自然环境中观察样品开辟了可能性。
