Thermal properties design strategy

A remaining crucial technological milestone to pass for an implanted device remains the stability of the biocatalytic fuel cell, which should be expressed in months or years rather than days or weeks. Recent reports on the use of BOD biocatalytic electrodes in serum have, for example, highlighted instabilities associated with the presence of 02, urate or metal ions [99, 100], and enzyme deactivation in its oxidized state [101]. Strategies to be considered include the use of new biocatalysts with improved thermal properties, or stability towards interferences and inhibitors, the use of nanostructured electrode surfaces and chemical coupling of films to such surfaces, to improve film stability, and the design of redox mediator libraries tailored towards both mediation and immobilization. 

The remainder of this overview chapter provides fimdamental background information related to transport of small molecules in polymers and then describes materials design strategies to prepare polymers with excellent permeability and selectivity properties for both supercriticd gas separations and vapor separations. In addition to high permeability and selectivity, membranes must also be stable in industrial process environments, which may be chemically and/or thermally challenging. For example, due to chemical stability and thermal transition temperatures of polymers used in gas separations, these materials are typically used at or near ambient temperatures. The chapter by Bayer et al. in this book describes the use of selective crosslinking of polyimides to prepare high performance membrane materials that are stable to 300°C. 

Properties of the analyte, such as volatility, sensitivity to light, thermal stability and chemical reactivity, all have to be considered when designing a sampling strategy. These factors need to be taken into account to ensure the quality of the sample does not degrade before the measurements are made. 

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