Optimized Na+/Cl–Selective Colorimetric Optode Arrays for Wearable Sweat Analysis: Paving the Way for Cystic Fibrosis Diagnostics

August 9, 2026

Preprints.org Unknown

Overview

Na+ and Cl–selective colorimetric optode arrays and their measurement protocols have been optimized as a portable point-of-care (POC) alternative to the traditional sweat test for cystic fibrosis (CF) diagnosis. This research aims to provide an analytical foundation for integration into wearable devices, enabling in-situ sweat analysis. Fifteen chromoionophore-based sensor compositions were screened across physiologically relevant ranges (5–100 mmol/L), demonstrating that smartphone-based digital color analysis offers robust performance superior to research-grade cameras.

In Depth

Key Findings

As a portable point-of-care (POC) alternative to the crucial sweat test for cystic fibrosis (CF) diagnosis, Na+ and Cl–selective colorimetric optode arrays, along with their measurement protocols, have been successfully optimized. This research aims to establish an analytical foundation for integrating these sensors into wearable devices, thereby enabling on-site sweat analysis.

Technical/Clinical Details

The study systematically screened fifteen different chromoionophore-based sensor compositions within the physiologically relevant Na+ and Cl- concentration range of 5–100 mmol/L. Chromoionophores are dyes that change color upon binding to specific ions, allowing ion concentration to be measured by detecting this color shift. The optimized compositions demonstrated clear color changes in the high chloride concentration range, which is critical for CF diagnosis. A significant finding of this research was the demonstration that smartphone cameras, used for digital color analysis, provide accurate and robust quantification of sensor color changes, outperforming expensive research-grade cameras. This directly translates to cost reduction and improved accessibility by eliminating the need for specialized laboratory equipment. Designed for integration into wearable devices, this sensor system can deliver rapid results from even small sweat samples, making it suitable for continuous monitoring and regular self-testing.

Background & Context

Cystic fibrosis diagnosis traditionally relies on specialized sweat tests (Pilocarpine Iontophoresis Sweat Test) performed in professional laboratories. While accurate, this test requires specialized equipment and trained personnel, posing accessibility challenges, particularly in developing countries and remote areas. The development of portable POC diagnostic devices holds the potential to overcome these geographical and economic barriers, facilitating early diagnosis and contributing to improved patient outcomes. Advances in wearable technology enable the seamless integration of such POC diagnostics into patients’ daily lives.

Strategic Significance & Outlook

The optimized Na+ and Cl–selective colorimetric optode arrays form a critical foundation for the future of wearable sweat analysis technology. Future developments are expected to involve multiplexing this technology to create integrated wearable sensors capable of simultaneously measuring other CF-related biomarkers (e.g., pH, glucose, lactate). Given the widespread adoption of smartphones, this device could become an extremely valuable tool for patients in remote areas or individuals requiring regular self-monitoring. While larger-scale validation trials and regulatory approvals are necessary for clinical implementation, its potential is immense, promising to revolutionize the diagnosis and management of CF patients.

Source: https://www.preprints.org/manuscript/202608.0334

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