# Hydrophobic Deep Eutectic Solvent‐Enhanced Filaments: A Green Breakthrough for Additive‐Manufactured Electrodes

## TL;DR

A new sustainable filament using a hydrophobic deep eutectic solvent improves the performance of 3D-printed electrochemical sensors.

## Contribution

This is the first integration of hydrophobic deep eutectic solvents into a sustainable, additive-manufactured electrode filament.

## Key findings

- The filament's electrical conductivity improved with HDES, reducing resistance significantly.
- The electrode showed enhanced electrochemical performance and was successfully used to detect acetaminophen in water.
- The material combines recycled and bio-based components, supporting green analytical technologies.

## Abstract

Advancing sustainable materials for functional devices is a key challenge in green chemistry. This study reports, for the first time, the integration of a hydrophobic deep eutectic solvent (HDES) into a conductive filament composed of recycled polylactic acid (rPLA), carbon black, cellulose, and bio‐based castor oil, yielding a sustainable material with enhanced performance. The resulting composite not only incorporates renewable and recycled components but also exhibits enhanced mechanical and electrochemical performance. Cellulose enhanced the mechanical properties and printability of the filament, while HDES significantly improved its electrical conductivity, reducing bulk resistance from (1.16 ± 0.1) to (0.86 ± 0.02) kΩ representing an improvement over the previously reported CB/cellulose/rPLA electrode, and increased electrochemical performance. Electrochemical characterization of the fabricated electrodes demonstrated superior redox behavior, with enhanced charge‐transfer rates and electroactive surface areas compared to other bespoke filaments. The CB/cellulose/HDES/rPLA electrodes were successfully applied to the voltammetric determination of acetaminophen in water samples, achieving a linear concentration range of 5.0–300 µM and a limit of detection of 0.12 µM. These findings highlight the potential of HDES‐modified filaments in the development of novel, sustainable, high‐performance additive‐manufactured electrochemical sensors, combining additive manufacturing with green materials with enhanced functionality.

This study presents the first use of hydrophobic deep eutectic solvents (HDESs) in a sustainable filament for additive manufacturing electrochemistry. The HDES–cellulose synergy enhances printability and conductivity. Made from recycled and bio‐based materials, the filament offers improved performance with reduced plastic and carbon content, advancing green analytical technologies.© 2026 WILEY‐VCH GmbH