# Green low-cost carbon nanodots-polyurethane composites with novel anisotropic anti-quenching mechanism for strain sensing

## TL;DR

This paper introduces a low-cost, non-toxic, highly stretchable carbon dot-polyurethane composite sensor that exhibits instant photoluminescence response to strain, utilizing a novel anisotropic anti-quenching mechanism for effective strain sensing.

## Contribution

It presents a scalable green fabrication method for stretchable fluorescent composites with a new anisotropic anti-quenching mechanism based on controlled distribution of carbon dots.

## Key findings

- PL intensity responds instantly to strain up to 250%
- PL peak remains non-shifted but varies in intensity under strain
- Discovered anisotropic anti-quenching mechanism based on particle distribution

## Abstract

A new type of nontoxic low-cost sensor is reported here, whose photoluminescence (PL) intensity is instantly responsive to the external strain applied over a large range (up to 250% strain). Highly stretchable fluorescent composites of carbon dots (CDs) and polyurethane (PU) are fabricated via a scalable green chemistry method by conveniently dispersing CDs in the aqueous solution of PU. It is discovered that, upon tensile deformation, the PL peak of the CD-PU film remains non-shifted but displays varied intensity. The observed PL responses to strain are ascribed to the enlarged inter-particle distance of CDs along the tensile direction (z axis), although a higher degree of aggregation is resulted in the other two axes. The PL-dependence on the anisotropic patterns of CDs in solid state points to a new mechanism to overcome aggregation-induced quenching by controlling the distribution behaviors of the fluorescent species.

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Source: https://tomesphere.com/paper/1907.13231