Application of light emitting diodes as solid state light sources in analytical chemistry



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Several analytical systems were developed with light emitting diodes (LEDs) as solid state light sources. With an LED as a light source, liquid core waveguide (LCW) channels on silicon were fabricated and showed much higher light transmittance than similar untreated channels. This chip-scale optical measurement system can be used for microanalysis of chemical and biological samples. An LED-based planar flow-through detector was fabricated and used for absorbance, fluorescence, and spectroelectrochemical measurements. This small, inexpensive, and versatile detector can be used both for dedicated chemical analyses and for pedagogical purposes. The Dual-wavelength LED-based absorbance detector has been used to compensate the effects of refractive index change and sample turbidity. Cost-effective balanced demodulators have been used to collect and separate two LED signals from a single photodiode. Several UV-LEDs have been used to develop NO2 photolytic converters. Many benefits can be obtained from the use of UV-LEDs as light sources for NO2 photolytic converters: light weight, low power consumption, higher energy efficiency, and compactness of design.