title: Retrograde and Direct Wave Locomotion in a Photosensitive Self-Oscillating Gel.
abstract: Crawling motion mediated by retrograde and direct waves, that is, in the opposite or the same direction, respectively, as the muscular wave that generates it, is a fundamental mode of biological locomotion, from which more complex and sophisticated locomotion modes involving outgrowths such as limbs and wings may have evolved. A detailed general description of muscular wave locomotion and its relationship with other modes of locomotion is a challenging task. We employ a model of a photosensitive self-oscillating gel, in which chemical pulse waves and a stimulus-responsive medium play roles analogous to nerve pulses and deformable muscles in an animal, to generate retrograde and direct waves under non-uniform illumination. Analysis reveals that the directional locomotion arises from a force asymmetry that results in unequal translation lengths in the push and pull regions associated with a pulse wave. This asymmetry can be modulated by the kinetic parameters of the photosensitive Belousov-Zhabotinsky reaction and the performance parameters of the gel, enabling a transition between retrograde and direct wave locomotion.
authors.affiliation: College of Chemical Engineering, China University of Mining and Technology, Xuzhou, 221008, Jiangsu, P. R. China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ren
authors.affiliation: College of Chemical Engineering, China University of Mining and Technology, Xuzhou, 221008, Jiangsu, P. R. China.
authors.forename: Weibing
authors.initials: W
authors.lastname: She
authors.affiliation: College of Chemical Engineering, China University of Mining and Technology, Xuzhou, 221008, Jiangsu, P. R. China. gaoqy@cumt.edu.cn.
authors.forename: Qingyu
authors.identifier: 0000-0002-8484-7828
authors.initials: Q
authors.lastname: Gao
authors.affiliation: College of Chemical Engineering, China University of Mining and Technology, Xuzhou, 221008, Jiangsu, P. R. China.
authors.forename: Changwei
authors.initials: C
authors.lastname: Pan
authors.affiliation: College of Chemical Engineering, China University of Mining and Technology, Xuzhou, 221008, Jiangsu, P. R. China.
authors.forename: Chen
authors.initials: C
authors.lastname: Ji
authors.affiliation: Department of Chemistry and Volen Center for Complex Systems, MS 015, Brandeis University, Waltham, 02454-9110, Massachusetts, USA. epstein@brandeis.edu.
authors.forename: Irving R
authors.identifier: 0000-0003-3180-4055
authors.initials: IR
authors.lastname: Epstein
keywords: Belousov-Zhabotinsky reaction; direct waves; gels; locomotion; retrograde waves