Li Wenjian, Li Longfei, Shi Qingfan, Yang Mingcheng, Zheng Ning
School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Soft Matter. 2022 Jul 27;18(29):5459-5464. doi: 10.1039/d2sm00134a.
Spontaneous collective oscillation may emerge from seemingly irregular active matter systems. Here, we experimentally demonstrate a spontaneous population oscillation of active granular particles confined in two chambers connected by a narrow channel, and verify the intriguing behavior predicted in simulation [M. Paoluzzi, R. Di Leonardo and L. Angelani, Self-sustained density oscillations of swimming bacteria confined in microchambers, , 2015, (18), 188303]. During the oscillation, the two chambers are alternately (nearly) filled up and emptied by the self-propelled particles in a periodic manner. We show that the stable unidirectional flow induced due to the confined channel and its periodic reversal triggered by the particle concentration difference between two chambers jointly give rise to the oscillatory collective behavior. Furthermore, we propose a minimal theoretical model that properly reproduces the experimental results without free parameters. This self-sustained collective oscillation could serve as a robust active granular clock, capable of providing rhythmic signals.
自发的集体振荡可能出现在看似不规则的活性物质系统中。在此，我们通过实验证明了限制在由狭窄通道连接的两个腔室中的活性颗粒的自发群体振荡，并验证了模拟中预测的有趣行为[M. 保卢齐、R. 迪莱昂纳多和L. 安杰拉尼，《限制在微腔室中的游泳细菌的自持密度振荡》，《物理评论快报》，2015年，(18)，188303]。在振荡过程中，两个腔室被自推进颗粒以周期性的方式交替（几乎）填满和排空。我们表明，由受限通道引起的稳定单向流动及其由两个腔室之间的颗粒浓度差异触发的周期性反转共同导致了振荡集体行为。此外，我们提出了一个最小理论模型，该模型能够在没有自由参数的情况下正确再现实验结果。这种自持集体振荡可以作为一个强大的活性颗粒时钟，能够提供有节奏的信号。
