A MEMS nanoindenter with an integrated AFM cantilever gripper for nanomechanical characterization of compliant materials

Abstract

This work presents the development of a MEMS nanoindenter that uses exchangeable AFM probes for quasi-static nanomechanical characterization of compliant and ultra-compliant materials. While the electrostatic micro-force transducer of the MEMS nanoindenter provides a maximum indentation depth up to 9.5 µm with a maximum output force of 600 µN, experimental investigations reveal that it can achieve a depth and force resolution better than 4 pm Hz−1/2 and 0.3 nN Hz−1/2, in air for f≥ 1 Hz. A passive AFM probe gripper is integrated into the MEMS nanoindenter, allowing the nanoindenter to utilize various AFM probes as an indenter for material testing. A proof-of-principle experimental setup has been built to investigate the performance of the MEMS nanoindenter prototype. In proof-of-principle experiments, the prototype with a clamped diamond AFM probe successfully identified an atomic step (∼0.31 nm) within a Si < 111 > ultraflat sample using the scanning probe microscopy mode. The nanomechanical measurement capability of the MEMS nanoindenter prototype has been verified by means of measurements of reference polymer samples using a silicon AFM probe and by means of measurements of the elastic properties of a PDMS sample using a spherical diamond-coated AFM probe. Owing to its compact and low-cost but high-resolution capacitive readout system, this MEMS nanoindenter head can be further applied for in-situ quantitative nanomechanical measurements in AFMs and SEMs.

An area-variant type MEMS capacitive sensor based on a novel bionic swallow structure for high sensitive nano-indentation measurement

“…Sensing performances of the proposed sensor were summarized and compared with existing MEMS capacitive sensors in the aspects of sensitivity, linearity, measurement range, resolution, noise floor, and Allan deviation, as shown in Table 6. The proposed sensor presented a higher force sensitivity of 98.54 aF/nN, which was much higher than that in the gap-variant type devices utilizing narrow initial comb spacing with the value of 58.82 aF/nm [22] and the areavariant type devices utilizing flexible springs with values of 8.18 aF/nN [25] and 27.29 aF/nN [27]. The proposed sensor also exhibited excellent linearity larger than 0.9996, which was only smaller than the area-variant type devices with the value of 0.9997 [27], but the measurement range of the proposed sensor was 142 µN and much larger than that in [27] with a small value of 0.97 µN.…”

“…Besides, some supporting flexures were implemented to decrease the sensor stiffness and increase force sensitivity. An area-variant type sensor with folded springs has been proposed with the sensitivity of 8.18 af/nN [25]. Based on the non-linear buckling behavior [26], asymmetric three buckling springs was developed for an area-variant type sensor for an improved sensitivity of 27.29 af/nN [27], but the spring buckling effect only exists within a small range of 109.38 nm.…”

C2.2 - Development of a conductive MEMS-SPM for nanoelectrical characterisation of nanostructured materials

“…It is worth noting that averaged properties of energy harvesting devices can now be measured, but a quantitative link and correlation between the performance of single NWs and that of the overall device is lacking. Within the frame of the EMPIR project 19ENG05 NanoWires, a microelectromechanical system (MEMS) based scanning probe microscope (MEMS-SPM) head [1] has been developed, with the aim to characterize the electrical properties of single nanowires with diameters <100 nm.…”

Nanoindentation of tungsten: From interatomic potentials to dislocation plasticity mechanisms

“…A pop-in event that defines the elastic to plastic deformation transition is produced as the indenter tip starts to penetrate the surface; it is often used as a reference point for analyzing the mechanical behavior of a material, as it can provide insight into the internal structure of the sample, which gives the opportunity to explore the mechanisms of plastic deformation initiation responsible for modification of mechanical properties of the material [5]. In addition, nanoindentation-induced plastic patterning is a process that involves the creation of patterns or structures in a material at the nanoscale with a wide range of applications, including the fabrication of nanostructured surfaces with enhanced functionalities and the development of new materials with tailored mechanical properties [6]. Plastic patterning due to nanoindentation is highly affected by the applied load, surface orientation, temperature, and the properties of the material itself, which needs a fundamental understanding of the materials deformation at the plastic zone beneath the indented surface region [2].…”