Trident-shaped fully 3D-printed electrochemical sensor for real-time measurements

Accurate analysis of fresh fruit and vegetable samples typically relies on complex instrumentation, skilled personnel, and extensive sample preparation, limiting its accessibility for decentralized testing. To overcome these challenges, we developed a fully 3D-printed, trident-shaped electrochemical sensor for direct, in situ detection of target analytes without any sample pre-treatment. The device was fabricated using low-cost, commercially available conductive and insulating filaments, and designed for seamless integration with portable or smartphone-connected potentiostats. The custom trident geometry enabled direct insertion into fruit and vegetable samples, eliminating the need for sample pre-treatment steps. Among tested configurations, rectangular working electrodes printed with simple infill patterns at 70 % printing speed exhibited optimal electrochemical performance, underscoring the critical impact of electrode design and printing parameters on sensor response. Linear sweep voltammetry was selected for its simplicity, rapid data acquisition, and compatibility with field-based applications. As a proof of concept, the sensor was used to quantify ascorbic acid in fresh orange, tomato, and kiwi samples. The results showed excellent correlation (≥99 %) with gold-standard LC-MS/MS analysis, validating the sensor's reliability for direct, on-site measurements. The device also exhibited strong intra- and inter-batch reproducibility (RSD < 5 %) and reusability (up to 18 measurements per sensor). With an estimated manufacturing cost of only €0.32, the platform presents a robust, low-cost, and sustainable solution for real-time quality monitoring. Its versatility supports future adaptation for detecting additional compounds such as pesticides and sugars, advancing on-field diagnostics in agriculture and food safety.