High-resolution of particle contacts via fluorophore exclusion in deep-imaging of jammed colloidal packings

TL;DR

This paper introduces a novel fluorescence-based method to achieve high-resolution detection of contact networks in jammed colloidal packings, enabling detailed analysis of their structural properties near marginal stability.

Contribution

The study presents a new fluorophore exclusion technique for precise contact detection in colloids, allowing for experimental insights into jamming physics and validation of theoretical models.

Findings

Determined scaling laws of force distributions and soft modes.

Measured structural properties near marginal stability.

Validated universality class predictions for jammed colloids.

Abstract

Understanding the structural properties of random packings of jammed colloids requires an unprecedented high-resolution determination of the contact network providing mechanical stability to the packing. Here, we address the determination of the contact network by a novel strategy based on fluorophore signal exclusion of quantum dot nanoparticles from the contact points. We use fluorescence labeling schemes on particles inspired by biology and biointerface science in conjunction with fluorophore exclusion at the contact region. The method provides high-resolution contact network data that allows us to measure structural properties of the colloidal packing near marginal stability. We determine scaling laws of force distributions, soft modes, correlation functions, coordination number and free volume that define the universality class of jammed colloidal packings and can be compared with theoretical predictions. The contact detection method opens up further experimental testing at the interface of jamming and glass physics.