Light-addressable potentiometric sensor based on precise light intensity modulation for eliminating measurement error caused by light source

To eliminate measurement error caused by fluctuation, distortion and noise of light source output in a light-addressable potentiometric sensor (LAPS) system, LAPS system based on precise light intensity modulation is presented in this study. A superluminescence LED (SLED) module, with a home-made multi negative feedback SLED driver, is proposed as the precise light source in this system. A high-speed optical fiber spectrometer is introduced for on-line monitoring and long period intensity compensation. The precise light source provides light output to LAPS, and keeps light intensity on sensitive surface to meet sine rules with low distortion and low noise. Furthermore, it is immune from variation of ambient temperature. Detailed optical parameters of precise light source are presented and compared with conventional light source. H+ measurements for LAPS system based on precise light intensity modulation were given and compared with system with conventional light source. From contrast experiments, it can be deduced that LAPS system based on precise light intensity modulation has better linearity, higher accuracy and lower noise than LAPS system with conventional light source. (C) 2012 Elsevier B.V. All rights reserved.