<title>Spectro-electrochemical sensors: materials, incorporation of planar waveguide technologies, and instrumentation</title>

Abstract

The detailed kinetics and associated optical waveforms of the spectroelectrochemical sensor in competitive binary mixtures of analytes are presented. The extension of the sensor concept to planar waveguide structures is described. Two different planar waveguide designs have been made and evaluated. One design was an asymmetric slab waveguide with the waveguide layer sandwiched between a silica substrate and a chemically-selective film. The other design was a channel waveguide, which consisted of an ion-exchanged channel between two gold electrodes in a "bus bar" configuration. These new designs are described in detail and evaluation of them with respect to operation of the sensor in the near ultraviolet region is discussed. Results with the devices in demonstration of the novel spectroelectrochemical concept with three modes of selectivity are given. Instrumentation developed specifically for operation of the sensors and acquisition of sensor data is described.

Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 9. Incorporation of Planar Waveguide Technology

“…Another possibility is that the modulation might, at least in part, be caused by the refractive index of the electrode varying with potential. Several studies 14,34,46 have shown, however, that the contribution from such a variation is negligible. The net result of our measurements is that there is an inherently large optical absorbance change in our ITO to be expected as the potential is cycled in electromodulation experiments and that this change scales linearly with applied potential.…”

“…The potential advantages of waveguides − over MIR devices are several: (1) increased sensitivity and better detection limits due to higher density of reflections; (2) greater versatility in choice of optical designs, including more sophisticated configurations, such as Mach Zehnder interferometers; and (3) the ability to micromachine sensors in complex platforms. The uses of waveguides for chemical sensing have been amply reported in the literature. , Previously reported types of planar waveguide chemical sensors include channel − and slab (or planar) − designs and Mach Zehnder interferometers. − …”

“…The uses of waveguides for chemical sensing have been amply reported in the literature. 9,10 Previously reported types of planar waveguide chemical sensors include channel [11][12][13][14] and slab (or planar) [15][16][17] designs and Mach Zehnder interferometers. [18][19][20] There have been several reports of waveguide designs for spectroelectrochemical sensing.…”