An optical chemical sensor using self-assembled monolayers based on surface plasmon resonance

A novel optical chemical sensor based on surface plasmon resonance (SPR) was presented. The sensor was different from popular SPR sensors that modulated angle of incident light at fixed excitation wavelength. The sensor presented here is designed on the basis of fixing the angle of incident light and measuring the change of resonant wavelength in the wavelength range of 400-800 nm. The intensity of the reflected light is the minimum at the resonant wavelength. Molecular self-assembly in solution is used to form a sensing membrane on the silver substrate. The compound used to form the monolayer is SH(CH2)OSO(CH2)(2)SH. Because -SH and silver can easily yield a silver-thiolate bond and the monolayer is firmly stuck on the silver substrate, the sensitivity of the sensor is improved clearly. Dimethylamine in water was determined by using this sensor and quantitative determination limit is 6.7x 10(-5) mol/L.