This work describes a novel thread-based microfluidic device to perform capillary electrophoresis separation and capacitively coupled contactless conductivity detection. Polyester threads with a diameter of about 315 mu m were assembled (stretched) in a 3D-printed platform containing solution reservoirs and platinum electrodes. Separation of potassium, sodium, and lithium ions was achieved within 1 min with good peak resolutions and limits of detection close to 1 mu mol L-1. Inversion of the electroosmotic flow direction by adding a cationic surfactant in the running electrolyte was demonstrated. The applicability of the thread-based microfluidic devices was successfully evaluated by the determination of sodium and potassium ions in commercial samples of diet soft drinks Ver menos