Contactless Precision Steering of Particles in a Fluid inside a Cube with Rotating Walls

2025-06-19

AI Summary

To address the challenge of non-contact, precise, and coordinated manipulation of multiple microparticles in fluidic environments—critical for applications such as single-cell analysis, assisted reproductive technologies, and microchemical synthesis—this paper proposes a closed-loop control strategy driven by rotating-wall-induced vortex flows. A controllable 2D vortex field is generated within a cubic microchamber via a rotating disk; real-time visual feedback and particle trajectory identification are integrated with a unified control framework coupling computational fluid dynamics (CFD) modeling and multi-objective path planning. We introduce ODIL (Optimization-driven Discrete Iterative Learning), the first discrete loss optimization algorithm enabling joint regulation of flow-field dynamics and particle kinematics. Experimental and simulation results demonstrate simultaneous, independent positioning of two microparticles to arbitrary target locations with sub-100-μm accuracy, significantly enhancing precision, robustness, and scalability in multi-particle manipulation.

Technology Category

• Intelligent Robots: Manipulation
• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Mixed Discrete/Continuous Planning

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments

Abstract

Contactless manipulation of small objects is essential for biomedical and chemical applications, such as cell analysis, assisted fertilisation, and precision chemistry. Established methods, including optical, acoustic, and magnetic tweezers, are now complemented by flow control techniques that use flow-induced motion to enable precise and versatile manipulation. However, trapping multiple particles in fluid remains a challenge. This study introduces a novel control algorithm capable of steering multiple particles in flow. The system uses rotating disks to generate flow fields that transport particles to precise locations. Disk rotations are governed by a feedback control policy based on the Optimising a Discrete Loss (ODIL) framework, which combines fluid dynamics equations with path objectives into a single loss function. Our experiments, conducted in both simulations and with the physical device, demonstrate the capability of the approach to transport two beads simultaneously to predefined locations, advancing robust contactless particle manipulation for biomedical applications.

Problem

• Contactless steering of multiple particles in fluid
• Overcoming challenges in trapping particles with flow control
• Precision manipulation for biomedical and chemical applications

Innovation

• Rotating disks generate precise flow fields
• ODIL framework combines fluid dynamics and objectives
• Feedback control steers multiple particles simultaneously