Display omitted •A low-cost new conductive ink based-graphite powder and commercial glue is proposed.•A new flexible electrochemical sensor was proposed using Ecoflex™ as substrate.•The proposed sensor was applied in the dopamine detection in synthetic sweat samples.•The proposed sensor was applied in the paracetamol detection in synthetic sweat and drug samples. Flexible, fully printed electrochemical sensors can be employed for non-invasive clinical analyses, which require biocompatibility and wearability. Herein, we report on a flexible electrochemical sensor printed on an Ecoflex™ substrate with a conductive ink made with craft glue, graphite, acetone, ethyl acetate, and glycerin. Under optimized conditions for the electrochemical sensor, square wave voltammetry was used to detect paracetamol in the range from 7.0 to 100 μmol L−1 and dopamine from 3.0 to 100 μmol L−1, with detection limits of 1.4 μmol L−1 and 78 nmol L−1, respectively. The sensor was suitable for rapid detection of paracetamol and dopamine in artificial sweat with recovery between 90 and 110%, being unresponsive to interference from other molecules. The electrochemical sensors can be screen printed at low cost and with mass production and adapted for microfluidic and wearable (bio)devices.