标题： 形状依赖的方向反转在各向异性催化微游动器中 显示英文标题

标题： Shape-dependent direction reversal in anisotropic catalytic microswimmers

摘要： 活性粒子的推进方向是自推进系统的一个关键特征，它取决于推进机制和环境条件。 在这里，我们使用3D微打印的催化活性粒子，实验表明，当活性粒子具有各向异性形状时，推进方向会随着燃料浓度的增加而改变。 我们发现，圆盘、环形体和弯曲杆在过氧化氢浓度增加时会反转运动方向——在低浓度时以惰性侧向前运动，在高浓度时以催化侧向前运动。 相反，球体和直杆不会出现这种反转。 我们观察到，方向反转与游泳者的基底材料组成及其尺寸无关，仅发生在各向异性粒子中，由于它们的伸长形状，溶质浓度最大值的位置不稳定，可以被底物诱导的限制所改变。 我们的测量结果表明，除了铂催化的过氧化氢反应发生变化外，具有伸长形状并能产生足够限制的粒子对此变化更为敏感。 显示英文摘要

摘要： The propulsion direction of active particles is a key feature in self-propelled systems and depends on the propulsion mechanism and environmental conditions. Here, using 3D micro-printed catalytically active particles, we experimentally show that the propulsion direction can change with increasing fuel concentration when the active particle possesses an anisotropic shape. We find that discs, tori, and bent rods reverse their direction of motion with increasing hydrogen peroxide concentration--moving with their inert side forward at low concentrations and with their catalytic side forward at high concentrations. In contrast, spheres and straight rods do not exhibit this reversal. We observe that direction reversal is independent of the base material composition of the swimmer and its size, and only occurs for anisotropic particles where, due to their elongated shape, the location of the solute concentration maximum is unstable and can be shifted by substrate-induced confinements. Our measurements suggest that in addition a change in the platinum-catalyzed reaction of hydrogen peroxide occurs, to which particles with elongated shapes that induce sufficient confinement are more sensitive.