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Non-Hermitian fluctuations enable model-free particle manipulation
Summary
Scientists have developed a new way to precisely move and sort microscopic particles—like tumor cells in a blood test or microplastic bits in water—using electric fields, without needing to pre-map the system in detail. Instead of relying on complex calibrations, their method reads energy loss patterns in real time to figure out how to steer particles, even when other objects are floating around unpredictably nearby. This could make tools for early cancer detection and water contaminant removal more practical to build and use in messy, real-world conditions rather than only in tightly controlled lab setups.
Contactless manipulation of microscopic matter is central to applications ranging from the isolation of circulating tumor cells in liquid biopsies to the removal of microplastics from environmental water. Electromagnetic approaches are particularly attractive because fields can be structured within compact microfluidic systems using either light or simple electrode architectures. However, precise manipulation requires calibrated models of the field distribution and accurate knowledge of the properties of both the object and the surrounding medium, which limits applicability to well-characterized, static systems. Here we show that energy dissipation itself provides sufficient information for deterministic particle control. Instead of relying on explicit field calibration, our approach exploits an original relationship between particle position, energy dissipation, and electromagnetic body forces, which can be accessed experimentally through variations of conductance matrices. By extracting force-shaping voltage patterns from these measurements, we demonstrate fully automated closed-loop manipulation of silica microbeads in one and two dimensions, including in the presence of other freely moving particles in a disordered background. These results establish a pathway toward deterministic force control by deliberately measuring and exploiting the non-Hermitian response of the system to engineer electromagnetic momentum transfer. This framework expands micromanipulation into realistic, dynamically evolving environments, where wave-matter interactions cannot be fully pre-characterized or eliminated through design.