MICRO (Multimaterial, Integrated, Compact, Ready-to-Plug, One-Step 3D-Printed): A Simple-to-Use Electrochemical Device for On-Site Analysis and Drug Screening

3D printing has emerged as a transformative technology in electroanalytical chemistry, enabling the rapid, low-cost, and reproducible mass fabrication of portable devices and sensors for several areas such as environmental, clinical, food, and forensic applications. Herein, we present a multimaterial, integrated, compact, ready-to-plug, and one-step additively manufactured electrochemical cell (MICRO-EC^3D). This all-in-one device was fabricated using a dual-extruder 3D printer and comprises a single unit containing the three electrodes/tracks (conductive carbon black-polylactic acid, CB-PLA) as well as the body containing an embedded mini solution reservoir (polyethylene terephthalate glycol, PETG). This arrangement eliminates the assembling of external accessories and allows the introduction of miniaturized stirrers. Unlike previous similar 3D-printed devices, the proposed microcell is readily interfaced to mobile apparatus (hand-held potentiostats and smartphones) through user-friendly USB-based connectors (wireless, crocodile clip, or banana pin). After a quick chemical (immersion in 5.0 M NaOH for 3 min) and electrochemical treatment (+1.4 V for 200 s and -1.0 V for 200 s in 0.5 M NaOH), this device showed performance comparable to a commercial carbon screen-printed electrode for model analytes (ferricyanide, paracetamol, and nitrite). The analytical use of the device was demonstrated for the square-wave voltammetric detection of anabolic steroid oxymetholone (OXM), in which two linear responses (1.0 to 5.0 and 6.0 to 10.0 μM; <i>R</i> ² > 0.99) and a limit of detection of 0.21 μM were obtained. These values were suitable for the screening of OXM in three seized samples, yielding results consistent with gas chromatography-mass spectrometry. These findings evidence the potential of MICRO-EC^3D as an easy-to-use, portable, and low-cost (<ten cents) tool for on-site preliminary forensic analysis and for increasing the acceptance and popularity of electrochemical methods, mainly among inexpert analysts.