Key Engineering Materials Vols. 523-524

Abstract: In this paper, we propose a high throughput method to fabricate ordered metal nano dot array on a plastic film by combination of patterning by nano plastic forming, coating, annealing, and transferring to a plastic film. The effects of process parameters such as indentation load, annealing temperature on the formation of gold nano dot array and dot transfer ratio to a PDMS film are investigated. The results show that an ordered gold nano dot array is successfully formed on the pre-patterned substrate. The transfer of an ordered gold nano dot array to PDMS film is demonstrated.

Abstract: Heart beat measurement is useful not just for medical use but also for daily healthcare monitoring and for sports. Photoplethysmography is an optical pulse measurement method that measures the variation of light absorption of the blood flow in capillary. Fingertip and earlobe, which are suitable places for this method, are not suitable for wearing sensors in daily life. Measurement at wrist will be more favorable. Technical difficulties of applying photoplethysmography measurement on wrist are: a) blood flow variation and change of sensor orientation caused by body motions, and b) low sensitivity compared to measurement at fingertips or earlobes because of the low capillary density in the tissue. We derived a transfer function that expresses the relationship between body acceleration and change in capillary blood flow based on a simple fluid dynamics model of artery and capillary. Preliminary experiments have shown that motion the artifacts can be reduced by subtracting the change of blood flow estimated from body acceleration. This method is different from conventional frequency filtering methods that do not consider the relationship between the body motion and the changes in the capillary blood flow. Furthermore, sensor head suspension mechanism has been employed in order to stabilize the sensor orientation with respect to the skin as well as the applied force on the skin.

Abstract: Micro/nano positioning is one of important techniques to operate bio-cell and micro assembly. For realizing the precise positioning, the various piezo-driven stages have been already proposed and micro/nano scale resolution has been achieved. However, it is pointed out that the existing precision positioning tools are too large compared to operating area. Their devices are too difficult to combine other devices and use in tight environment like under microscope. In this paper, a precise positioning method with wire connected mechanism under microscope is proposed. The proposed positioning system is simply composed actuators including piezoelectric element and super extra-fine wires. By applying wire connected mechanism, the saving of larger work environment compared to traditional devices is hoped.

Abstract: In this paper, a novel Z-θZ micro-stage is designed and constructed by utilizing an impact friction drive. The stage is configured by two driving units, a moving element and a stage base. Each driving unit consists of two PZTs and a friction element. One end of each PZT is fixed on the stage base, and the other end is attached on a permanent magnet as the friction element. The moving element, which is a steel cylinder, is supported and moved by the friction element. Magnetic force generated by permanent magnet is utilized to stabilize the driving condition between the moving element and the friction element for the friction drive. The size of the stage is less than 1 cm3. The stroke and the maximum speed of the stage in the Z-direction are 3.8 mm, 5.7 mm/s, respectively. The stroke in the θZ-direction is unlimited and the maximum rotational velocity is 26 rpm.

Abstract: The vibration damping of guide ways is an important factor in the design of feed drive mechanisms for machine tools. Linear rolling bearings are often used as guide ways because of their low friction. However, there are no quantitative evaluation methods for its damping. Thus, this paper describes a quantitative estimation method for the stiffness and damping capacity of a linear roller guide through an experiment and a mathematical model. The stiffness and damping coefficient of the linear roller guide are identified through the frequency resonance function and mathematical model of the feed drive mechanism. It is shown that a lubricant film can effectively increase the stiffness and damping capacity of the linear roller guide.

Abstract: Since micro products have become smaller, the requirements concerning precision and accuracy for producing machine tools to manufacture such small parts increased. Consequently, each component of a machine tool needs to conform to these requirements. A flexure-based feed unit, a clamping system and mechanical couplings are briefly presented. These components can quickly be reconfigured, which allows for a new modular micro machine tool system. Each component incorporates individual precision and accuracy leading to an overall error budget for a machine tool system. This is methodically addressed in the contribution.

Abstract: This paper introduces a sensitivity improvement of biochemical sensor by a combination of self-assembly of particles and optical lens. Typical biochemical sensor utilizes fluorescence emitted as a result of specific reaction. The sensitivity can be enhanced with the increase in surface area of self-assembled fine particles. In addition, optical lens was used to convergent the fluorescent light to simplify the system configuration. Silica particles of 1m diameter were assembled on a convex lens and modified with protein labeled with fluorescent material. Then, the spatial distribution of fluorescence was measured by changing the angle from the optical axis and distance from the lens. The results show sensitivity improvement up to 600 %. However, it was found that the effect of scattering should be taken into account for further sensitivity improvement.

Abstract: Control of adhesion force between cells and medical materials is important for artificial tissue such as tooth, bone and joint. There are many trials to control the adhesion by modifying the surface of culture media. One of these is roughness control of culture media. In this study, the cells cultured on microstructured surface were pushed by a cantilever on a micromanipulator. The deflection of cantilever was measured to calculate the force, and the crucial force when cells were detached from media was quantified as cell adhesion force. Microstructured surface was fabricated from poly-dimethylsiloxane (PDMS). The structure was replicated from Si substrate that was etched through a mask of self-assembled particles. The profile of the mold is cone array of which pitches is same with mask particle's diameter 1 or 5 μm. Thus, the media has regular pits which correspond to the pillar. The effect of pitch and height of the structures on the adhesion force were made clear.

Abstract: Localized surface plasmon resonance (LSPR) based sensors are a well established technology utilized for label-free biochemical sensing in immunoassay, medical diagnostics and environmental monitoring. The understanding of asymmetric metal nanoparticles, new object for complex, coupled plasmon systems providing localized significantly enhanced E-field, is central to a wide range of novel applications and processes in science of higher sensitive sensing systems. However, few methods are available for actual characterization of such nanostructures at the single particle level. Here we propose a precise and large sized scale fabrication technique for asymmetric nanoshells array with nanogaps of several tens of nanometers for LSPR sensor through atmospheric pressure plasma etching processes. A nanoshell was simply constructed by laminating thin Au films on periodic isolated polymer nanoparticles template. This nanoshells array was expected to exhibit specific near-infrared plasmonic properties. When measuring the sensitivity, nanoshells array exhibited a high sensitivity to changes of surrounding refractive index and showed a higher sensor figure of merit than the alternative structures. This indicated that the enhanced plasmon E-field in the asymmetric nanostructures improved sensor performance. Our fabrication technique and the optical properties of the arrays will provide useful information for developing new plasmonic applications.

Abstract: The use of a needle-free injector (NFI) that inject drag solution into the skin by applying pressure is increasing with an increase in the number of diabetes patients. The medical treatment of diabetes involves insulin administration several times a day. Therefore, the purpose of this study is to improve the usability of the NFI and the development of the NFI that can be used for multiple injections with a one-time administration preparation. The existing the NFI inject the drag solution by the application of elastic force. The problem with these the NFI is the maintenance of a constant injection force each time that they are used, because the elastic force decreases with an increase in the number of injection times. We found that it is possible to assist the injection force by generating an impact force at the time of injection. Therefore, the impact clearance is set in the NFI. Certain experiments have been carried out to investigate the relationship between the impact clearance and injection force. The results of these experiments reveal that the injection force is maintained at a constant value by increasing the impact clearance when the spring power decreases. A trial model of the multiple-injecting the NFI is developed on the basis of these results. It is evaluated under the condition that a constant injection force is maintained even in the case of multiple injections.