Modular biosensor reaction-cell

An approach to simultaneously monitor the processes of a biosensor transducer surface and the bulk of the sample solution is presented. A novel PDMS (Poly-DiMethyl-Syloxane) based modular biosensor reaction-cell is described, which is suitable for the parallelised electrochemical monitoring of biosensor electrode arrays by means of its dual connector array and for optical spectroscopic monitoring of the bulk of the surrounding sample solution by means of micro transmission dip probes insertable inside the reaction cell. An experimental setup with 280 and 520 mm3 reaction-cell volumes was tested and characterized. 2 x 13 individually addressable electrode connectors were easily realisable in order to meet the requirements of electrochemical functionalities. For the optical spectroscopic capabilities 0.13 O.D. (Optical Density unit), corresponding to 0.68 pmol/&mu l concentration of the DNA (Deoxyribo Nucleic Acid) used was found to be the minimum, and 3.43 O.D., corresponding to 20.59 pmol/&mu l concentration of the DNA used was found to be the maximum of the absorbance range which can be monitored with ca. 5\% standard deviation using a certain parameter setting during a certain measurement

Toward reliable morphology assessment of thermosets via physical etching: Vinyl ester resin as an example

The morphology of peroxide-cured, styrene crosslinked, bisphenol A-based vinyl ester (VE) resin was investigated by atomic force microscopy (AFM) after ‘physical’ etching with different methods. Etching was achieved by laser ablation, atmospheric plasma treatment and argon ion bombardment. Parameters of the etching were varied to get AFM scans of high topography resolution. VE exhibited a nanoscaled nodular structure the formation of which was ascribed to complex intra- and intermolecular reactions during crosslinking. The microstructure resolved after all the above physical etching techniques was similar provided that optimized etching and suitable AFM scanning conditions were selected. Nevertheless, with respect to the ‘morphology visualization’ these methods follow the power ranking: argon bombardment > plasma treatment > laser ablation