Shin ChaeHo, Jeon InSu, Khim Zheong G, Hong J W, Nam HyoJin
Interdisciplinary Program of Nano-Science and Technology, Seoul National University, Seoul 151-742, Korea.
Rev Sci Instrum. 2010 Mar;81(3):035109. doi: 10.1063/1.3327822.
A detection method using a self-sensing cantilever is more desirable than other detection methods (optical fiber and laser beam bounce detection) that are bulky and require alignment. The advantage of the self-sensing cantilever is its simplicity, particularly its simple structure. It can be used for the construction of an atomic force microscopy system with a vacuum, fluids, and a low temperature chamber. Additionally, the self-actuating cantilever can be used for a high speed scanning system because the bandwidth is larger than the bulk scanner. Frequently, ZnO film has been used as an actuator in a self-actuating cantilever. In this paper, we studied the characteristics of the self-sensing and self-actuating cantilever with an integrated Wheatstone bridge circuit substituting the ZnO film with a lead zirconate titanate (PZT) film as the actuator. We can reduce the leakage current (to less than 10(-4) A/cm(2)) in the PZT cantilever and improve sensor sensitivity through a reduction of noise level from the external sensor circuit using the Wheatstone bridge circuit embedded into the cantilever. The self-sensing and actuating cantilever with an integrated Wheatstone bridge circuit was compared with a commercial self-sensing cantilever or self-sensing and actuating cantilever without an integrated Wheatstone bridge circuit. The measurement results have shown that sensing the signal to noise level and the minimum detectable deflection improved to 4.78 mV and 1.18 nm, respectively. We believe that this cantilever allows for easier system integration and miniaturization, provides better controllability and higher scan speeds, and offers the potential for full automation.
一种使用自感应悬臂的检测方法比其他检测方法(光纤和激光束反射检测)更具优势,因为其他方法体积庞大且需要校准。自感应悬臂的优点在于其简单性,特别是结构简单。它可用于构建具有真空、流体和低温腔的原子力显微镜系统。此外,自驱动悬臂可用于高速扫描系统,因为其带宽大于整体扫描仪。通常,氧化锌薄膜已被用作自驱动悬臂中的致动器。在本文中,我们研究了集成惠斯通电桥电路的自感应和自驱动悬臂的特性,该悬臂用锆钛酸铅(PZT)薄膜替代氧化锌薄膜作为致动器。通过使用嵌入悬臂的惠斯通电桥电路降低外部传感器电路的噪声水平,我们可以降低PZT悬臂中的漏电流(至小于10^(-4) A/cm²)并提高传感器灵敏度。将集成惠斯通电桥电路的自感应和自驱动悬臂与商用自感应悬臂或无集成惠斯通电桥电路的自感应和自驱动悬臂进行了比较。测量结果表明,信号噪声水平和最小可检测挠度分别提高到了4.78 mV和1.18 nm。我们认为这种悬臂便于系统集成和小型化,提供更好的可控性和更高的扫描速度,并具有实现完全自动化的潜力。