# A single-particle mechanofluorescent sensor

## TL;DR

A new sensor using PDA particles detects mechanical stress in microchannels, with fluorescence changes indicating fluid properties and aiding in body simulations.

## Contribution

A novel mechanofluorescent sensor system using PDA particles is developed for real-time monitoring of mechanical stresses in microchannels.

## Key findings

- PDA particles show nonlinear fluorescence emissions influenced by fluid viscosity and nanoparticle/biomolecule presence.
- Computational simulations suggest a blue-to-red fluorescence transition requires ~307 μJ of torsion energy.
- The sensor system can simulate problematic human body regions in vitro, aiding future medical exploration.

## Abstract

Monitoring mechanical stresses in microchannels is challenging. Herein, we report the development of a mechanofluorescence sensor system featuring a fluorogenic single polydiacetylene (PDA) particle, fabricated using a co-flow microfluidic method. We construct a stenotic vessel-mimicking capillary channel, in which the hydrodynamically captured PDA particle is subjected to controlled fluid flows. Fluorescence responses of the PDA particle are directly monitored in real time using fluorescent microscopy. The PDA particle displays significant nonlinear fluorescence emissions influenced by fluid viscosity and the presence of nanoparticles and biomolecules in the fluid. This nonlinear response is likely attributed to the torsion energy along the PDA’s main chain backbone. Computational fluid dynamic simulations indicate that the complete blue-to-red transition necessitates ~307 μJ, aligning with prior research. We believe this study offers a unique advantage for simulating specific problematic regions of the human body in an in vitro environment, potentially paving the way for future exploration of difficult-to-access areas within the body.

A mechano-fluorescence sensor system using polydiacetylene (PDA) particles monitors mechanical stresses in microchannels mimicking stenotic vessels, with fluorescence varying by fluid viscosity and particle collisions, aiding in in-vitro simulations.