Dr Mercedes Vázquez

The electrochemical stability of poly(3,4-ethylenedioxythiophene) (PEDOT) is studied in view of its use as ion-to-electron transducer (solid contact) in all-solid-state ion-selective electrodes (ISEs). PEDOT is electrochemically deposited on glassy carbon (GC) and the resulting GC/PEDOT electrodes are studied by cyclic voltammetry(CV), electrochemical impedance spectroscopy (EIS) and potentiometry. Valinomycin-based all-solid-state K⁺-ISEs are constructed by placing a K⁺-selective poly(vinyl chloride) (PVC)-based membrane on the GC/PEDOT electrode (solid contact). The influence of dissolved O₂ and CO₂ on the potential of the GC/PEDOT electrodes and of all-solid-state K⁺-ISEs is studied. PEDOT is compared with polypyrrole(PPy) as the solid contact material. A significant difference between the two conducting polymers (CPs) is that PEDOT is less sensitive to O₂ and CO₂ (pH) than PPy. Therefore, PEDOT is a promising new candidate as ion-to-electron transducer (solid contact) in all-solid-state ISEs based on solvent polymeric membranes that are permeable to O₂ and CO₂.

The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes.

This review critically summarises recent novel and advanced achievements in the application of monolithic materials and related porous polymer gels in micro-fluidic devices appearing within the literature over the period of the last 5 years (2005–2010). The range of monolithic materials has developed rapidly over the past decade, with a diverse and highly versatile class of materials now available, with each exhibiting distinct porosities, pore sizes, and a wide variety of surface functionalities. A major advantage of these materials is their ease of preparation in micro-fluidic channels by in situpolymerisation, leading to monolithic materials being increasingly utilised for a larger variety of purposes in micro-fluidic platforms. Applications of porous polymer monoliths, silica-based monoliths and related homogeneous porous polymer gels in the preparation of separation columns, ion-permeable membranes, preconcentrators, extractors, electrospray emitters, micro-valves, electrokinetic pumps, micro-reactors and micro-mixers in micro-fluidic devices are discussed herein. Procedures used in the preparation of monolithic materials in micro-channels, as well as some practical aspects of the micro-fluidic chip fabrication are addressed. Recent analytical/bioanalytical and catalytic applications of the final micro-fluidic devices incorporating monolithic materials are also reviewed.