2022 Fiscal Year Final Research Report

Elucidation of the mechanism of liquid crystal piezoelectric effect induced by flow and development of power generation devices

Research Project

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Project/Area Number	20H02059
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	一般
Review Section	Basic Section 18040:Machine elements and tribology-related
Research Institution	Kochi University of Technology
Principal Investigator	Chono Shigeomi 高知工科大学, システム工学群, 教授 (20155328)
Co-Investigator(Kenkyū-buntansha)	辻知宏高知工科大学, システム工学群, 教授 (60309721) 西脇永敏高知工科大学, 環境理工学群, 教授 (30237763)
Project Period (FY)	2020-04-01 – 2023-03-31
Keywords	液晶 / 非ニュートン流体力学 / 圧電効果 / MEMS
Outline of Final Research Achievements	From molecular dynamics simulations to quantify the effects of molecular aspect ratio, temperature, and shear rate, as well as continuum mechanics simulations, it was found that some liquid crystal molecules that were in rotational motion in the shear plane oriented outside the shear plane to reduce their torque when they were subjected to shear strain above a threshold value. We assumed that this out-of-plane orientation behavior is related to the onset of the piezoelectric effect. Using the Leslie-Ericksen theory, the relationship between the viscoelastic coefficients and the induced shear force was studied numerically. The L-E theory has nine viscoelastic coefficients that depend on the posture of the liquid crystal molecules. By finding out a coefficient that is dominant in piezoelectric properties, we attempted to synthesize a new liquid crystal with excellent piezoelectric properties.
Free Research Field	流体工学
Academic Significance and Societal Importance of the Research Achievements	我々の周囲には、微小ではあるが未利用なエネルギーが多数存在しており、これらを電気エネルギーに変換できる新技術の創出と、高効率変換が可能な新しい物質の創製が求められている。液晶は弾性率が低い柔らかい物質「ソフトマター」であり、巨視的には通常の液体のように振る舞うが、微視的には結晶の異方性を有しているので、圧電効果を発現すると予想される。つまり、省資源・省エネルギー化に貢献するだけでなく、電力供給が困難な環境下で、センサー等の電子デバイスのユビキタス自立電源としても期待される。応用形態としては、軸受けの潤滑剤として用いる軸受け発電や、歩行や車両の踏圧で発電する発電床を想定している。