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Nowadays, there is increased demand for wearable sensors for sweat glucose monitoring in order to facilitate diabetes management in a patient-friendly and noninvasive manner. This work describes a wearable glucose monitoring device in the form of an electrochemical ring (e-ring) fabricated by 3D printing. The 3D-printed e-ring consists of three carbon-based plastic electrodes (fabricated using a conductive filament) integrated at the inner side of a ring-shaped flexible plastic holder (fabricated using a nonconductive filament). The e-ring is modified with an electrodeposited gold film and is coupled to a miniature potentiostat directly addressable by a smartphone, offering the possibility for nonenzymatic amperometric self-testing of glucose levels in human sweat. Optical and electrochemical techniques are employed for the characterization of the e-ring. The device is resistant to mechanical bending and enables noninvasive glucose detection in sweat in the physiologically relevant concentration range of 12.5–400 μmol L–1 without interference from common electroactive metabolites. The 3D-printed e-ring bridges the gap between the existing fabrication/sensing technologies and the desired operational features for glucose self-monitoring and may be employed as a paradigm of in-house fabricated wearable sensors.

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In this work, we developed a novel all-3D-printed device for the simple determination of quetiapine fumarate (QF) via voltammetric mode. The device was printed through a one-step process by a dual-extruder 3D printer and it features three thermoplastic electrodes (printed from a carbon black-loaded polylactic acid (PLA)) and an electrode holder printed from a non-conductive PLA filament. The integrated 3D-printed device can be printed on-field and it qualifies as a ready-to-use sensor, since it does not require any post-treatment (i.e., modification or activation) before use. The electrochemical parameters, which affect the performance of the sensor in QF determination, were optimized and, under the selected conditions, the quantification of QF was carried out in the concentration range of 5 × 10−7–80 × 10−7 mol × L−1. The limit of detection was 2 × 10−9 mol × L−1, which is lower than that of existing electrochemical QF sensors. The within-device and between-device reproducibility was 4.3% and 6.2% (at 50 × 10−7 mol × L−1 QF level), respectively, demonstrating the satisfactory operational and fabrication reproducibility of the device. Finally, the device was successfully applied for the determination of QF in pharmaceutical tablets and in human urine, justifying its suitability for routine and on-site analysis.