http://nanomechanics.mit.edu/sites/default/files/documents/Gouldstone_2000.pdf

Discrete and continuous deformation during nanoindentation of thin films

This tutorial reviews various noncontact optical sensing techniques that can be used to measure distances to objects, and related parameters such as displacements, surface profiles, velocities and vibrations. The techniques that are discussed and compared include intensity-based sensing, triangulation, time-of-flight sensing, confocal sensing, Doppler sensing, and various kinds of interferometric sensing with both high- and low-coherence sources.

Optical methods for distance and displacement measurements

Catalyst preparation using plasma technologies

A novel soft strain sensor capable of withstanding strains of up to 100% is described. The sensor is made of a hyperelastic silicone elastomer that contains embedded microchannels filled with conductive liquids. This is an effort of improving the previously reported soft sensors that uses a single liquid conductor. The proposed sensor employs a hybrid approach involving two liquid conductors: an ionic solution and an eutectic gallium-indium alloy. This hybrid method reduces the sensitivity to noise that may be caused by variations in electrical resistance of the wire interface and undesired stress applied to signal routing areas. The bridge between these two liquids is made conductive by doping the elastomer locally with nickel nanoparticles. The design, fabrication, and characterization of the sensor are presented.

/pdf/a-soft-strain-sensor-based-on-ionic-and-metal-liquids-favsbzanns.pdf

A Soft Strain Sensor Based on Ionic and Metal Liquids

Investigation of the relationship between elastic modulus and hardness based on depth-sensing indentation measurements

Nanoindentation is a simple and effective means for evaluating the mechanical properties of thin films. In such circumstances, nanoindentation testers have been developed and commercialized by some companies. In this study, we tested the standard four specimens using six different types of testers and established a method to evaluate the nanoindentation data. The method requires only two correction factors; one is the frame compliance, Cf, of the testers, and the other is the error of the detection of the original surface which includes both the truncation of the indenter apex and the damage of the surface caused by the preloading of the indenter. The latter correction is conducted by adding a correction length, ΔhC, to the measured penetration depth, h. It was found that the values ΔhC increase with decrease in the hardness of material and are very sensitive to the performance of the testers.

Simplified method for analyzing nanoindentation data and evaluating performance of nanoindentation instruments

Nanoindentation load–displacement behavior of pure face centered cubic metal thin films on a hard substrate

A novel optical-fiber displacement sensor is proposed and demonstrated. It consists of a laser diode light source, an optical-fiber probe, and two photodetectors. The bundling of the probe is sectioned into three parts: a centrally positioned fiber in the bundle for illumination, the first-neighbor fibers for receiving (part I), and the remaining fibers for receiving (part II). The ratio of the difference to the sum of the output signals from the part I and the part II receiving fibers can eliminate the variation in the sensitivity of the sensor to reflectivity of the target. The performance of the sensor is geometrically analyzed. The working distance is determined by the distance from the centered illuminating fiber to the boundary between the part I and the part II receiving fibers. The experimental measurements made with three different reflectivity targets confirm that the sensor performance is independent of the three reflectivities, as predicted by the analysis.

Development of a differential optical-fiber displacement sensor

The performance of a multifiber optical lever was geometrically analyzed by extending the Cook and Hamm model [Appl. Opt. 34, 5854–5860 (1995)] for a basic seven-fiber optical lever. The generalized relationships between sensitivity and the displacement detection limit to the fiber core radius, illumination irradiance, and coupling angle were obtained by analyses of three various types of light source, i.e., a parallel beam light source, an infinite plane light source, and a point light source. The analysis of the point light source was confirmed by a measurement that used the light source of a light-emitting diode. The sensitivity of the fiber-optic lever is inversely proportional to the fiber core radius, whereas the receiving light power is proportional to the number of illuminating and receiving fibers. Thus, the bundling of the finer fiber with the larger number of illuminating and receiving fibers is more effective for improving sensitivity and the displacement detection limit.

Geometrical analysis of an optical fiber bundle displacement sensor

In a nanometer order nanoindentation test, roundness or truncation of the indenter tip cannot be avoided. In this paper, we have analyzed the indentation problem of a rounded triangular indentation into a layered elastic half-space by a finite element analysis and then established a method to estimate the intrinsic elastic modulus of the film from the nanoindentation data. The method was applied to analyze the nanoindentation data of a less-than-10 nm penetration depth on a 10 nm thick diamondlike carbon film deposited on a 50 nm thick magnetic layer.

Kohichi Tanaka

Papers

Simplified method for analyzing nanoindentation data and evaluating performance of nanoindentation instruments

Nanoindentation load–displacement behavior of pure face centered cubic metal thin films on a hard substrate

Development of a differential optical-fiber displacement sensor

Geometrical analysis of an optical fiber bundle displacement sensor

Nanoindentation of a 10 nm thick thin film