Ultrafast laser structuring of graphene-based multi-zone heaters for the detection of antioxidant capacity

This study presents a non-contact processing method of heating devices using maskless ultrafast laser direct structuring of graphene (G) films coated on the alumina ceramic (Al₂O₃) substrates for antioxidant capacity (ATC). The effect of ATC temperatures on the electrode structures of the electrical resistance and electromechanical properties of G-based multi-zone (GM) device was investigated. The fabricated GM device with four electrode structures could be regarded as an on-site heater in assisting preheating treatment. The required laser processing parameters of energy fluence, pulse repetition rate, and scanning speed were 7.02 J/cm², 300 kHz, and 500 mm/s, respectively. For the GM heater, a steady-state temperature of 100 °C could be reached within 10 s under a lower applied voltage of 14 V. The experimental results demonstrated that the electrothermal performance of GM devices was used to control the ATC preheating process. The absorbance values of ATC ranged from 0.5 ± 0.01 to 1.07 ± 0.04 measured by a spectrophotometer at a wavelength of 700 nm. Moreover, the absorbance value increased with increasing concentration of standard solution that the high absorbance represented the ATC solution with high reducing power. Successful operation of GM heater with a simple and promising technique should find application in laser-ablated G electrodes for an advanced inspection instrument of ATC.