Electro-Mechanical Couplings in Liquid Crystsals

John E Harden, ,

Kent State University

With the energy demands of today, exploration for new sources is of the utmost importance. This work explores possible roles in which liquid crystals can produce electrical signals (electricity) via mechanical distortions. For example, bent core molecules have been found to have high flexoelectric coefficients when directly flexed. Typical Giant Flexoelectric coefficients are 10nC/m order. This is verified by measuring the current produced from a oscillatory bend of the sample and by measure the bending produced by application of an applied electric field. These materials may be used to produce small scale power generators. Naturally these materials need to be studied and their flexoelectric coefficients measured. Also, phospholipids, which make up a large percentage of the cell membrane, are not well studied for their liquid crystalline properties. This work found that shearing these cell membranes can produce a piezoelectric signal. The cell membrane is basically a chiral smectic A (SmA*) liquid crystal. However, a shear will produce tilt which would make it a chiral smectic C (SmC*). This symmetry breaking induces a piezoelectric signal within the cell membrane. In essence, the cell membrane is itself a generator of electricity. This newly discovered membrane piezoelectricity may play important roles in cellular processes such as ion channels, mechano-reception and magneto-reception.

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