# Direct Methamphetamine Sensing in Flowing Wastewater via a 3D-Printed Flow-Through Cell

## TL;DR

A 3D-printed device was developed to detect methamphetamine in flowing wastewater, offering a portable solution for public health and law enforcement.

## Contribution

The first demonstration of direct electrochemical sensing of methamphetamine in flowing wastewater using a 3D-printed flow-through platform.

## Key findings

- The device achieved a detection limit of 15.9 µg L−1 in non-flow and 211.2 µg L−1 in flow conditions.
- The system enabled discrimination between methamphetamine and its precursor APAAN in a single run.
- The design supports portable, near-real-time sewer surveillance for methamphetamine.

## Abstract

The rapid, field-ready detection of methamphetamine (MET) directly in sewage under flow remains a bottleneck for public health and law enforcement surveillance. We engineered a low-cost, 3D-printed flow-through electrochemical cell that houses a commercial screen-printed carbon electrode and operates in both non-flow and flow regimes. The platform was validated using the [Ru(NH3)6]3+/2+ couple, confirming negligible kinetic hindrance and suitability for voltammetric sensing under convective transport. Using square wave voltammetry and chronoamperometry, MET was quantified in filtered wastewater, with limits of detection of 15.9 µg L−1 in non-flow and 211.2 µg L−1 in flow conditions. Specificity tests yielded well-separated faradaic responses for the pre precursor α-phenylacetoacetonitrile (APAAN) and for MET, while amphetamine produced only a weak signal, enabling side-by-side discrimination in a single run. To our knowledge, this is the first demonstration of direct electrochemical sensing of MET in flowing wastewater using a 3D-printed flow-through platform. The simple, disposable design provides an actionable foundation for portable, near-real-time sewer surveillance and motivates antifouling/auto-cleaning strategies for long-term deployment.