Microelectromechanical Systems for Nanomechanical Testing: Electrostatic Actuation and Capacitive Sensing for High-Strain-Rate Testing
Microelectromechanical Systems for Nanomechanical Testing: Electrostatic Actuation and Capacitive Sensing for High-Strain-Rate Testing
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DOI：
10.1007/s11340-019-00565-5
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发表时间：
2020-03
影响因子：
2.4
通讯作者：
Chengjun Li;D. Zhang;G. Cheng;Yong Zhu
中科院分区：
文献类型：
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作者：
Chengjun Li;D. Zhang;G. Cheng;Yong Zhu
关于纳米材料在高应变率下的力学性能的研究相对较少，这主要是由于缺乏有能力的纳米机械测试装置。本文介绍了一种用于高应变率纳米机械测试的新型片上微电子机械系统(MEMS)。该MEMS器件由一个静电梳状驱动器、两个电容式位移传感器和一个称重传感器组成。系统地模拟了装置在空气和真空中在交变和斜坡力作用下的动态响应。采用电容读数和高速成像两种方法对动态位移进行了测量，结果与建模结果吻合较好。虽然我们演示了在斜坡力作用下，S−1的最大恒定应变率超过200g，但有趣的是，本工作中使用的电容式读数由于带宽限制，只能测量高达22g S−1的应变率。为了证明这种新装置的实用性，在扫描电子显微镜下以10−5和10−S 1的应变率测试了金纳米线。提高应变速率可以获得更高的屈服强度和更大的塑性。
There have been relatively few studies on mechanical properties of nanomaterials under high strain rates, mainly due to the lack of capable nanomechanical testing devices. Here we present a new on-chip microelectromechanical system (MEMS) for high strain-rate nanomechanical testing. The MEMS device consists of an electrostatic comb drive actuator, two capacitive displacement sensors and a load cell. The dynamic responses of the device in air and in vacuum are systematically modeled under both alternating and ramp forces. Two methods, capacitive readout and high-speed imaging, are used to measure the dynamic displacements, which agree well with the modeling results. While we demonstrate the maximum constant strain rate over 200 s−1under ramp force, it is interesting to find that the capacitive readout used in this work can only measure strain rate up to 22 s−1due to its limit in bandwidth. To demonstrate the utility of this new device, gold nanowires are tested at strain rates of 10−5and 10 s−1inside a scanning electron microscope. Increasing strain rate is found to yield higher yield strength and larger ductility.