# Development of in situ real-time sensor for molecular contamination

## TL;DR

This paper introduces a new sensor to detect organic contamination in real-time for space applications.

## Contribution

The paper presents a novel microwave-based method for measuring thin organic contaminant layers in low-pressure environments.

## Key findings

- The microwave sensor shows a linear response to the thickness of paraffin and silicone oil deposits.
- The method can measure contamination from a few nanometers to several hundred nanometers.
- This approach is suitable for integration into on-board contamination detection systems.

## Abstract

Organic contamination is a major problem in the space industry, particularly for satellite optical devices. Although the standards governing this problem are extremely strict, there is no efficient method to measure the in situ, real-time deposition of organic contaminants. An original method based on thickness measurement is reported and tested in this paper. The use of microwave transduction allows to estimate the thickness of paraffin oil and silicone oil deposits from a few nanometers to several hundred nanometers in a low-pressure (mbar) environment. A linear response of the microwave sensor as a function of contaminant layer thickness is thus evidenced for both silicone and paraffin oils, paving the way for the integration of this method as an on-board contamination detection device.