# Simple Optical Fiber Sensor for Express and Cross-Sensitive Hydrogen Detection

## TL;DR

This paper introduces a simple and fast optical fiber sensor for detecting hydrogen that works well under various conditions and is resistant to interference from other gases.

## Contribution

A novel optical hydrogen sensor using a plasmon-active fiber with Pd and PDMS layers is proposed, offering cross-sensitivity protection and rapid response.

## Key findings

- The sensor detects hydrogen within tens of seconds and regenerates in about 2 minutes.
- The sensor is resistant to interference from gases like NO2, CH4, CO2, CO, and NH3.
- The sensor functions effectively from room temperature up to 80 °C with minor performance reduction at higher temperatures.

## Abstract

The utilization of hydrogen as an energy source is becoming
more
and more widespread. Since hydrogen is a highly explosive gas, its
use requires the development of inexpensive and simple sensors capable
of measuring hydrogen concentrations under a variety of conditions.
These sensors must meet several parameters, such as small size, light
weight, corrosion resistance, and remote operation capability. The
ideal hydrogen sensors should also be insensitive to the presence
of various interfering gases and humidity or temperature variation
and be protected against potential poisoning. In this work, we present
a simple optical hydrogen sensor that satisfies most of the above
criteria. The sensor is based on a plasmon-active multimode optical
fiber coated with Pd and PDM layers in a stepwise manner. The Pd layer,
deposited on the plasmon active area, ensures sensitivity toward hydrogen
through hydrogenation of Pd, leading to a significant shift in the
plasmon absorption band wavelength position. An additional PDMS layer
ensures sensor protection against various interfering gases (NO2, CH4, CO2, CO, and NH3),
including the moisture of sulfur-containing compounds. The sensor
response is measured within tens of seconds, while its regeneration
takes approximately 2 min. The operating temperature range is from
RT to 80 °C, with a slight decrease in sensor functionality at
an elevated temperature. The proposed structure is simple, allows
the removal of hydrogen detection, and can be used under various operation
conditions.