Flexible Dispense-Printed Electrochemical Biosensor for Aflatoxin M1 Detection Employing NaOH and Oxygen Plasma Electrode Pre-treatment

In this work, flexible dispense-printed biosensors for AFM1 detection in milk were fabricated on polyethylene terephthalate (PET) substrate employing sodium hydroxide (NaOH) bath and oxygen plasma (OP) pre-treatment. Thanks to the use of dispense-printed silver and silver/silver chloride electrodes, our flexible biosensors are able to detect a minimum AFM1 concentration of 0.010 μg/L, which is to the best of our knowledge the the best lower level of detection ever reported for AFM1 sensors. Even if sensors with untreated and treated electrodes yield the same sensitivity, NaOH bath and OP pre-treatments result in a reduction of the electrode resistance by 46%, and 21.6%, respectively. These results prove that pre-treatment is a useful technique to modify the electrical and surface properties of the dispense-printed electrodes, by removing binder polymers and impurities of the employed ink paste. Bendability tests showed a maintaned fuctionality even after 1000 bending cycles down to 9 mm radius with variations below 11%.