Accumulation and Analysis of Cuprous Ions in a Copper Sulfate Plating Solution

Knowledge of the behavior of cuprous ions (monovalent copper ion: Cu(I)) in a copper sulfate plating bath is important for improving the plating process. ...

Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

In this study, methods for the mechanoluminescent (ML) visualization of crack propagation and mechanical behavior to evaluate adhesive joints are ...

National Institute of Advanced Industrial Science and Technology (AIST)

We have investigated a photosensor that consists of a field emission transistor (FET) utilizing the biocomponent of the photosystem I (PSI) protein complex for use in an imaging device. The PSI was immobilized on a gold electrode via the self-assembling monolayer (SAM) of 3-mercapto-1-propanesulfonic acid sodium salt to obtain a PSI-modified gold electrode. As for the PSI-modified gold electrode, the basic photoresponses originating from the excitation of PSI, including the photocurrent (106 nA) and the photoresponse of the open-circuit voltage (photo-Voc: 28.6 mV), were characterized. Then, the PSI-modified gold electrode was linked to the gate of the FET using a lead line, and the device was successfully driven by the photoelectric signals from the PSI like a voltage follower circuit. Further, we successfully demonstrated that the PSI-based FET acts as a photosensor in imaging devices.

Photosensor based on an FET utilizing a biocomponent of photosystem I for use in imaging devices.

We have demonstrated an innovative ability of mechanoluminescent (ML) material as a light source for the first time. By appropriate smart size control and nondestructive mechanical stimulation, the ML particle can be considered a promising candidate of in situ light source for bio-imaging and photo-therapy even in a human body.

Mechanoluminescent light source for a fluorescent probe molecule.

In this study, we have investigated mechanoluminescent (ML) performance of single ML particle as ubiquitous light source. When using high-speed CCD camera with image intensifier and microscopic equipment, mechanoluminescence from single particle was observed. As to the quantitative ML evaluation of the single ML particle was carried out using photomultiplier, and successfully estimated the performance of the single ML particle as an intensity controllable light source in nW order. 

Performance of single mechanoluminescent particle as ubiquitous light source.

Plug and play: Photoinduced electron transfer occurs from photoexcited P700 in photosystem I (PSI) to a gold surface (see picture). A novel molecular connector system is used, in which an artificial molecular wire, which is assembled on the gold surface, was plugged into PSI by reconstitution. Analysis of the photoelectron transfer kinetics proved both the output of electrons from PSI and the effectiveness of the molecular wire.

Plugging a molecular wire into photosystem I: reconstitution of the photoelectric conversion system on a gold electrode.

The toughness and the durability under a high humidity condition of the interfaces in dissimilar adhesive joints of carbon-fiber-reinforced thermoplastic with a polyamide-6 matrix and Al alloy were evaluated by two test methods, in which a tensile opening load was applied to the specimens to cleave the interfaces apart in two different ways. In the double cantilever beam (DCB) test, the specimens were continuously pulled apart at a constant velocity, while in the wedge test, the specimens are pulled apart at a constant displacement. The crack growth along the interface in the DCB test was dynamically monitored with the assistance of mechanoluminescence for the accurate detection of the phenomena at the crack tip. The wedge test was employed for the evaluation of the durability of the interfaces under high humidity conditions. It was found that the adhesive joints were failed by various failure modes depending on the surface pretreatment and environmental conditions. Throughout the work, discussion was made concerned with the interfacial structures and the adhesion mechanism of dissimilar adhesive joints.

Toughness and Durability of Interfaces in Dissimilar Adhesive Joints of Aluminum and Carbon-Fiber-Reinforced Thermoplastics.

Can we visualise static electricity, which everyone in the world knows about? Since static electricity is generated by contact or peeling, it may be a source of malfunction of electronic components, whose importance is steadily increasing, and even cause explosion and fire. As static electricity is invisible, makeshift measures of static electricity are taken on various surfaces; there is also a common view that it is hard to take effective measures. Here we present a specific luminescent material, SrAlO: Eu, which emits light at excitation by an electrostatic charge in the air. Till now, in the interaction between electricity and luminescent materials, it was considered that emission of light is enabled by accelerated particles colliding with the luminescent material in vacuo. There have been no reports on luminescent materials being responsive to low-energy electrostatic charges under atmospheric pressure. Using SrAlO: Eu luminescent material discovered by us, we succeeded for the first time in static electricity visualisation in the form of green light. In addition to the fact that such static electricity induced luminescence assists in solving electrostatic-related problems in the industry, it also provides a new measurement method that facilitates the observation of previously invisible electric charges in the air.

Demonstration of static electricity induced luminescence.

Owing to their high thermal and optical performances, carbon nanotube (CNT) films are used in various photo-thermo-electric (PTE) applications, such as terahertz (THz) sensing and energy harvesting. To improve the performance of PTE devices, a device structure should be designed based on a deep understanding of the thermal and optical responses of the CNT film. However, the optical properties of CNT films in the THz frequency region remain unclear because of the difficulties associated with device processing and measurements. Herein, we report our findings on the thermal and optical characteristics of CNT films. The shape of the CNT film that maximizes the product of the thermal and optical factors (optimal structure of the PTE sensor) depends on the frequency of the irradiating electromagnetic wave. The optimal film thickness and width values for THz irradiation range from 300-600 nm and 50-70 µm, respectively. Subsequently, we fabricated a serially connected, multi-element PTE sensor with an optimal device structure and enhanced the detection sensitivity by approximately 13 times compared with a single-element PTE sensor. In addition, we demonstrated the first THz spectroscopy application using a PTE sensor. The findings of this study, thermal/optical factor enhancement, and micro-sized CNT film processing technology can be used to improve the performance of all CNT-based photothermal devices, including PTE sensors and thermoelectric generators.

Carbon nanotube-based, serially connected terahertz sensor with enhanced thermal and optical efficiencies.

Non-destructive testing of carbon-fiber-reinforced plastic (CFRP) laminates with bidirectional fiber bundles (twill-weave) using a mechanoluminescence (ML) technique was proposed. The dynamic strain distributions and fracture phenomena of the CFRP laminates in the tensile testing were evaluated by the fabricated ML sensor consisting of SrAlO:Eu (SAOE) powder and epoxy resin. The ML images for the ML sensor attached to the CFRP laminates with bidirectional fiber bundles gave a net-like ML intensity distribution similar to the original twill weave pattern. Specifically, it was found that the ML intensity on the longitudinal fiber bundle, which is the same as the tensile direction, is higher than that on the transverse fiber bundle. This indicates that the ML sensor can visualize the load share between fiber bundles in different directions of the CFRP laminate with high spatial resolution. Meanwhile, the ML sensor could also visualize the ultrafast discontinuous fracture process of the CFRP laminates and its stress distribution. The amount of SAOE powder in the ML sensor affects the tracking performance of the crack propagation. A higher SAOE amount leads to a fracture of the ML sensor itself, and a lower SAOE amount leads to poor ML characteristics.

Nao Terasaki

Advanced Manufacturing Research Institute,
Department of Electronics and Manufacturing,
Sensing System Research Center (SSRC),
Advanced Manufacturing Research Institute, Department of Electronics and Manufacturing

National Institute of Advanced Industrial Science and Technology (AIST)

Accumulation and Analysis of Cuprous Ions in a Copper Sulfate Plating Solution

Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

Nao Terasaki

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Advanced Manufacturing Research Institute,Department of Electronics and Manufacturing,Sensing System Research Center (SSRC),Advanced Manufacturing Research Institute, Department of Electronics and Manufacturing

National Institute of Advanced Industrial Science and Technology (AIST)

Accumulation and Analysis of Cuprous Ions in a Copper Sulfate Plating Solution

Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

Advanced Manufacturing Research Institute,
Department of Electronics and Manufacturing,
Sensing System Research Center (SSRC),
Advanced Manufacturing Research Institute, Department of Electronics and Manufacturing