Ryo Sakurai

The effect of blending particles with different conductivity on electrorheological properties

We have carried out a set of experiments using anhydrous carbonaceous particles to determine the effect on the electrorheological properties of blending particles of different conductivities. We find that there is a significant dip in the shear stress under an electric field as the concentration of higher conductivity particles is increased, showing that uniformity of the electrical properties among the particles is a most important factor in achieving optimum electrorheological fluid (ERF) performance. We explain this behavior by a simple model based on the strength of particle–particle interactions. Measurements of the dielectric permittivity show that the α parameter of the Cole–Cole expression provides an excellent way to express the degree of uniformity in the electrical properties. This gives a convenient method to evaluate the potential performance of an ERF.

Effect of matrix viscoelasticity on the electrorheological properties of particle suspensions

Abstract We have investigated the electrorheological properties of dispersions of semi-conducting particles in oils and elastomers. We focused on how the dynamic mechanical properties measured under oscillatory shearing change with the viscosity of the oil or the elasticity of the elastomer. The dependence on electric field and strain amplitude were also investigated. We found that the largest increment of the mechanical properties under electric fields was obtained when using oils of low viscosity and elastomers of low elasticity. The strain amplitude which produced the largest variation with electric field was found to be 0.1% for the elastomer systems, but significantly larger (1%) for the oil systems. These results are interpreted in terms of a model based on the competition between the dipole–dipole electrostatic interaction (which acts to maintain neighbouring particles together) and the shearing force due to the deformation of the matrix (which acts to separate the particles). We find that there are parallels between the electrorheological behaviour of particles dispersed in elastomers and the behaviour of particles dispersed in oils. These results should find application in the selection of suitable matrix materials for electrorheological suspensions.

A Flexible electronic-paper display with an ultra-thin and flexible LSI driver using quick-response liquid-powder technology

— A thin and flexible LSI driver with a thickness of less than 35 μm for a passive-matrix-driven Quick-Response Liquid-Powder Display (QR-LPD™) was successfully mounted onto the flexible printed circuit (FPC) and the back substrates of a flexible QR-LPD™. Amounted LSI driver on a plastic substrate shows no significant degradation in the driving performances and maintains physical flexibility without any connection failures. This technology can realize a fully flexible electronic paper in combination with a plastic-substrate QR-LPD™ fabricated by a roll-to-roll process.

10.3: Distinguished Paper: Ultra Thin and Flexible Paper‐Like Display using QR‐LPD® Technology

Really paper-like display as thin as 290 μm has been developed, which has a 160×160 array of pixels, 3.1-inch diagonal viewable image size, and white-paper appearance. Plastic substrate with 120 μm in thickness was used resulting in a flexible display which can be bent up to 20 mm in radius of curvature. This can be realized only by QR-LPD® technology.

A reflective-display QR-LPD®

Abstract— A novel reflective display [Quick-Response Liquid Powder Display (QR-LPD®)], has been developed. This paper-like display has the advantages of outstanding image stability, easy viewing, low-power consumption, and a high-response time. QR-LPD® will be promoted, initially, for use as electronic price-tag displays for merchandise. In addition, QR-LPD® is suitable for flexible display applications because it does not require TFT arrays or a high-temperature process while maintaining an excellent paper-like image as well as glass-type display compatibility.

68.2: Color and Flexible Electronic Paper Display using QR-LPD® Technology

We have developed a color and flexible electronic paper display using electronic liquid powder. Novel types of color display either colored powder or color filter are discussed. We have also developed a flexible display with low cost substrate films with a high throughput roll-to-roll manufacturing system. These technologies enable QR-LPD® to be used widely as an electronic paper display.

45.1: Invited Paper: Ultra‐thin and Flexible LSI Driver Mounted Electronic Paper Display using Quick‐Response Liquid‐Powder Technology

The thin and flexible LSI driver with a thickness of less than 40μm for passive-matrix driven Quick-Response Liquid Powder Display (QR-LPD™) was successfully mounted onto the flexible printed circuit (FPC). The mounted LSI on the plastic substrate shows no significant degradation in the driving performances and keeps physical flexibility without any failures of connection. This technology can realize the fully flexible electronic paper in combination with a plastic substrate QR-LPD™ fabricated by roll-to-roll process.

A quick‐response liquid‐powder display (QR‐LPD®) with plastic substrate

Paper-like displays as thin as 290 μm have been developed using QR-LPD technology. We fabricated two types of displays. One is a dot-matrix type with a 160 x 160 array of pixels and a 3.1-in.-diagonal viewable image size. The other is a segmented type for clock use. Each display has a paper-like appearance and exhibits high contrast. Plastic substrates with a thickness of 120 μm were used, resulting in flexible displays that can be bent up to a radius of curvature of 20 mm.

51.3: The Use of Transparent Conductive Polymer for Electrode Materials in Flexible Electronic Paper

Transparent conductive polymer of PEDOT/PSS has been applied to top electrodes of flexible electronic-paper display. High resolution electrode patterning of the polymer materials in a line shape has been performed by laser ablation method. An 8.4-in. diagonal and 82 dpi flexible electronic paper using quick response liquid-powder technology has been prepared by applying the patterned flexible substrates. The flexible electronic paper with PEDOT/PSS electrodes has exhibited comparable display properties to that consisting of ITO electrodes.

Relationship between electric current and matrix modulus in electrorheological elastomers

Abstract We have carried out a series of tests on electrorheological elastomers, which consist of semi-conducting solid particles dispersed in a low-conductivity silicone-based elastomer, with the investigations focussing on the dependence of the DC electric current on the elastomer modulus. We find that when other conditions are held constant, the electric current under a particular electric field shows a significant decrease when an elastomer of higher modulus is used. This behaviour is explained qualitatively using a simple model based on the mechanical equilibrium of two competing forces: the electrostatic attraction force between the two adjacent particles in the field direction, and the elastic squeezing force due to the elastomer between the particles which resists their approach.