Laser Induced Formation of Functional Metal Oxides for Enhanced Electrochemical Sensing

The use of electrochemical sensors in different sectors has highlighted the need for sensors with high sensitivity, low cost and high stability over time. However, the high cost, and low long-term stability of biomolecule electrochemical sensors have yielded the need for other approaches. Alternatively, metal oxides have shown promise to be used for sensing applications without the need of receptors but have yet to be widely adopted due to the complicated and expensive multistep manufacturing process associated with producing them. To develop the functional metal oxide surfaces, laser processing has been seen as an alternative, owing to the low costs, high degree of control and rapid processing time which can be adapted to more scalable manufacturing processes. The use of laser induced oxidation has shown great promise by creating highly localized modifications of the surface morphology without affecting the bulk properties of the metal, while providing a more stable and robust electrical connection between the oxide and bulk metal layer. Laser induced oxidation was used to develop of low cost, rapid detection electrochemical sensors, taking advantage of the create three-dimensional micro/nano oxide structures which exhibit enhanced electrocatalytic properties compared to that of bulk metal. Copper and nickel were laser processed to obtain the rapid, low cost and scalable manufacturing of electrochemical sensors for the detection of nonenzymatic glucose. The obtained laser-induced oxidized copper (LIO-Cu) and laser-induced oxidized nickel (LIO-Ni) contained highly nano/micro porous oxide structures which greatly increased the electrocatalytic activity enabling the detection of glucose. A systematic study of the composition, crystallinity, microstructure and wettability was conducted through the use characterization techniques including scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and water contact angle measurement. The electrochemical sensing performance of the devised sensors were tested against a range of glucose concentrations to test sensitivity and detection limit. The LIO-Ni sensor demonstrated a high linear sensitivity of 5222μA mM⁻¹cm^-2 over glucose concentration range of 5μM to 1.1mM, and the LIO-CU sensor demonstrated exceptional sensitivity of 6950μA mM⁻¹cm^-2over a wide range of 0.01 to 5 mM glucose concentration. The obtained results demonstrate the capability for laser processing to be adapted for a scalable manufacturing environment to produce rapid, low-cost and highly sensitive electrochemical sensors, which have application in various field of study including medicine and agriculture.