Detection and discrimination of low concentration gas contaminants by means of interferometrically-sensed polymers

Two optical techniques for bio- and chemical sensing were investigated. The methods are based on deviation of the optical properties of polymer transducers due to change in either index of refraction or dimension of the sensing element under molecular impact. The holographic interferometer technology developed at the University of Colorado observes interactions between an analyte and a transducer's surface and bulk. The second approach, a common path interferometer proposed by Dr. John Hall, focuses on surface interactions only. The two techniques complement each other, enabling the separation of surface and bulk interactions. This is critical for accurate description of chemical uptake and release dynamics, and therefore for obtaining parameters necessary for the analyte identification process. Preliminary sensitivity level of the systems is on the order of 10-5 RTU (refractive index units) with possible improvement down to 10-7 RTU