Author: Chun-Jen Chen

Presentation by Chun-Jen Chen at DPG Meeting of the Condensed Matter Section, 4th – 9th of Sep. 2022

Chun-Jen Chen in front of the big screen with his presentation slide. (Photo by Robert C. Löffler.)
On the 7th of September, Chun-Jen Chen gave a talk titled “Collective response of microrobotic swarms to external threats” during his participation of the 2022 DPG Meeting of the Condensed Matter Section in Regensburg, Germany. The 15-minute talk focused on the novel stratergy to implement extra feature into a collective social behaviour and corresponding experimental results with microrobotic colloidal particles. The talk also delivered prospective impact of such findings on microrobotic swarm design and undiscovered phase behaviours between collective behavioural states. The meeting gethered a wide range of bio-physists and active/soft-matter physists and trigged inspiring discussion across different projects.

You can find out more detail about the presented work as the contents of this talk was based on Chun-Jen and Clemens Bechinger’s publication at New J. Phys. 24 033001 (2022).

Collective response of microrobotic swarms to external threats published in New Journal of Physics

A swarm of microrobots, consist of active Janus colloids (middle right, not to scale), can form stationary swirl (upper) and respond to a threat as a whole (lower) when each individual follows cohesive “social rules”. Such rules are inspired by living animals and enable the swarm collective benefits, e.g. enhanced robustness of the response. (Image by C-J Chen.)
Collective response of microrobotic swarms to external threats

Chun-Jen Chen and Clemens Bechinger
New J. Phys. 24 033001 (2022)
doi: 10.1088/1367-2630/ac5374
repository: KOPS:56911

Many animal species organize within groups to achieve advantages compared to being isolated. Such advantages can be found e.g. in collective responses which are less prone to individual failures or noise and thus provide better group performance. Inspired by social animals, here we demonstrate with a swarm of microrobots made from programmable active colloidal particles (APs) that their escape from a hazardous area can originate from a cooperative group formation. As a consequence, the escape efficiency remains almost unchanged even when half of the APs are not responding to the threat. Our results not only confirm that incomplete or missing individual information in robotic swarms can be compensated by other group members but also suggest strategies to increase the responsiveness and fault-tolerance of robotic swarms when performing tasks in complex environments.

Press release at Universität Konstanz website:
How animal swarms respond to threats: With the help of microrobots, Konstanz physicists decode how swarms of animals respond effectively to danger [in English]

Talk by Chun-Jen Chen at Institute of Physics, Academia Sinica (Taiwan), 21 January 2022

This talk focused on the social collective response of a group of active particles to a threat, demonstrated in the figure above (the threat appeared at t = 0s). (Image by C-J Chen.)
On the 21st of January 2022, Chun-Jen gave a talk at Institute of Physics, Academia Sinica (Taipei, Taiwan) with title “Collective response of microrobotic swarms to external threats”. Chun-Jen shared and discussed about his most recent scientific work, which involves active Janus colloids and animal collective behaviours, with researchers and students of several fields, including biophysics, soft-matter, and surface/nano science.

Chun-Jen Chen attended the “Mobility, self-organization and swimming strategies” school, 18-29 October 2021

The school brought about a new collaboration on a simulation project with Vicsek-like model in complex environment (an example in upper with swimmers in black arrows showing their orientations), e.g. a turbulent flow (heatmap in upper panel), considered microswimmers that try to align to neighbors in a spatially-correlated noise (cartoon in lower). (Image by C-J Chen.)
From the 18th to the 29th of October 2021, Chun-Jen and two of his colleagues working on programmable active Janus colloids participated in the The 1st UCA FOX, UCA Fall program on Complex Systems 2021 “Mobility, self-organization and swimming strategies” hosted by Université Côte d’Azur in Nice and Fréjus.

The school was focused on three main topics: Swimming into complex environment – micro-swimming, Collective motion, and Machine learning applied to active particles, and covered a wide range of models regarding chemical and biological microswimmers.

The school was organised in lecture sections and project sessions for participants to collaborate in groups, in which PhD students and post-doctoral researchers could develop a research project in one of the three main topics of the school. Chun-Jen was involved in a simulation project on a Vicsek-like model in complex environment which is still ongoing.

Talk by Chun-Jen Chen at Institute of Physics, Academia Sinica (Taiwan), 25 February 2021

The topic of this talk covered the laser experiments enabling active particle steering (upper left), collective motion of such particles (middle) and connection to social animal behaviours, eg. fish school (lower). (Image by C-J Chen.)
On the 25th of February 2021, Chun-Jen gave a talk at the Institute of Physics, Academia Sinica (Taipei, Taiwan) about his research project at University of Konstanz. He explained how active Janus micro-spheres can be propelled and steered at the indivitual level in his experiment system and how such experiments are linked to studies of collective behaviours in living systems. The talk induced vivid discussions with audience of different backgrounds. Chun-Jen also shared experiences regarding PhD life in Germany with prospective young researchers in Taiwan.

Chun-Jen Chen presents his PhD project at the ActiveMatter online meeting, 10 September 2020

As our first event with full participation of both PIs and ESRs took place on the 10th of September 2020, all ESRs had a chance to introduce their PhD projects, and benefit from the collective discussion and feedback from the other members of the network.

Chun-Jen Chen (UKONS) briefly explained the Active Brownian Colloidal (ABC) system with real-time controls to displacements and orientations of each individual ABC particles. He further demonstrated the application of such ABC system in the investigation of spontaneous collective behaviours of living systems (also more detail here by UKONS), and how he would extend the study to higher non-equilibrium and more stimulus-interactive cases, e.g. collective prey-predator interactions.

Chun-Jen presentation is published along with all other ESR presentations on the network’s Youtube channel. You can also read about the meeting and get the full list of ESR presentation videos in the Event post.