Abstract:

It was proposed to introduce graphene(GR) with electrical and thermal conductivity into the photoresist SU-8 to prepare a conductive composite photoresist. The ultra-depth microscope and multimeter were used to investigate the dispersion and the conductivity of the composite photoresist, respectively. The results show that the composite photoresist is conductive when the mass fraction of graphene reaches 3%, and the dispersion of graphene is relatively uniform. Subsequently, a novel GR/SU-8 patterned electrode(GR/SU-8/ITO) with the designed pattern was prepared by photolithography on ITO glass surface. The composite conductive photoresist with 4%GR forms a conductive path with the ITO electrode, which increases the specific surface area of the electrode. After 40 cycles of cyclic voltammetry scanning, the redox current of the composite electrode was increased and the electrode performance was further improved. Finally, a hydrogen peroxide-free enzyme sensor was prepared on the surface of composite GR/SU-8/ITO electrode by electrochemical in situ reduction of copper nanoparticles. The excellent electron transfer ability of the electrode was verified by this simple enzyme-free sensing system. The prepared sensor has good linearity detection for hydrogen peroxide in the range of 1—20 mmol/L(R²=0.999). The stability of the obtained biosensor is excellent because the current response can still be maintained above 90% after 15 d. At the same time, the obtained sensor also has good selectivity and anti-interference which reflected in the nearly same current response to hydrogen peroxide in the presence of various interferents. In conclusion, the above results prove the application of the conductive photoresist in the field of electrochemistry. It is believed that the composite non-enzymatic electrochemical sensor has great application in point of care in the future.

Key words: Graphene, Conductive photoresist, Patterned electrode, Non-enzymatic sensor