Evaluation of a new disposable screen‐printed sensor strip for the measurement of NADH and its modification to produce a lactate biosensor employing microliter volumes

A combined sensor strip was fabricated by screen‐printing a Meldola Blue modified carbon working electrode and a Ag/AgCl combined reference/counter electrode alongside each other on a PVC substrate. This was investigated as an amperometric sensor for NADH, at an applied potential of 0 V, both in bulk solutions under hydrodynamic conditions and using 20 μL volumes without agitation. The former technique gave linear responses in the range 3–60 × 10−6mol dm−3 and the latter in the range 10−5 × 10−4 mol dm−3 of NADH. Further modification of the electrodes with NAD+ and lactate dehydrogenase converted the device to a biosensor for lactate both in spiked phosphate buffer and bovine serum. The sensors demonstrated good linear responses in the range 0–20 × 10−3 mol dm−3.