# Surface exciton polaritons: a promising mechanism for sensing applications

## TL;DR

This paper explores a novel surface exciton polariton (SEP) sensor at room temperature, replacing metal films with dye films in a Kretschmann-Raether setup, achieving higher sensitivity than traditional SPR sensors.

## Contribution

It introduces a new SEP-based sensing mechanism using J-aggregate dye films, demonstrating significantly improved sensitivity over conventional gold-based SPR sensors.

## Key findings

- Sensitivity of 118.18 °/RIU for gaseous analytes
- Sensitivity of 140.43 °/RIU for aqueous solutions
- SEP sensor outperforms traditional SPR sensors in sensitivity

## Abstract

The possibility of constructing a surface exciton polariton (SEP) based sensor at room temperature is explored. The proposed SEP sensor is based on the Kretschmann-Raether configuration of conventional surface plasmon resonance (SPR) sensor, where the metal thin film was replaced by the J-aggregate cyanine dye film. The excitation of SEP results in a strong electric field at the interface of TDBC and analyte, and exponentially decaying into the analyte, which is sensitive to the refractive index variations of analyte. The sensitivity of 118.1818 $^\circ/\text{RIU}$ (140.4286 $^\circ/\text{RIU}$) was achieved for the proposed SEP sensor within the refractive index range 1.0-1.001 (1.33-1.36) of gaseous analyte (aqueous solutions), which is about 2 (3.5) times higher than that of conventional gold-based SPR sensor. The significant superiority of the SEP sensor in sensitivity revealing SEP as a new promising mechanism for sensing applications.