Well-ordered polystyrene colloidal spheres for light addressable potentiometric sensor

Abstract

Light addressable potentiometric sensor (LAPS) is a flexible addressable potential sensor with many advantages including simple structure, high sensitivity, low manufacturing cost and light addressability. It can help us to achieve a high performance and low cost of LAPS to combine well-ordered polystyrene (PS) colloidal monolayer with fabricating of LAPS. This paper presents an alcohol-assisted interfacial fabrication method for fabricating low-cost, large-scale and well-ordered PS colloidal monolayer for LAPS in a simple laboratory. The effects of dispersants on PS colloidal self-assembly monolayer are investigated. The mechanism of well-ordered PS colloidal monolayer fabricated with methyl alcohol as the dispersant and the mechanism of disordered PS colloidal monolayer fabricated with ethyl alcohol as the dispersant are described in detail. The PS colloidal monolayer as a template, is used in fabrication of honeycomb meshed array working electrode to optimize performance of LAPS. Moreover, it is proved that the area ratio of the honeycomb meshed array to the silicon substrate is a constant which is independent of the diameter of the PS colloidal sphere. LAPS with honeycomb meshed array has an acceptable sensitivity of 53.47 mV/pH and high linearity of 99.8% in the measurement of pH. The change of photocurrent is also compared deeply for optimization. The results show that LAPS with honeycomb meshed array can reduce signal crosstalk between the detection points and improve addressability of LAPS.