Geordende moleculen in perspectief

Rede Wageningen, 16 mei 199

Sensitivity control of ISFETs by chemical surface modification

The response of ISFETs (ion-sensitive field-effect transistors) to concentrations of ions, especially H+ ions, is determined by the type of gate surface. Both the number of active surface sites and (proton) association and dissociation constants influence the sensitivity.\ud \ud In the case of a chemically-modified gate surface, a new surface is formed, which generally has a different sensitivity.\ud \ud It is shown that the original pH response of the gate oxide can be either lowered or increased, depending on the reactivity of the added groups. In general, coverage with apolar groups and reduction of the number of sites result in a lower pH response, while addition of basic or acidic groups as well as an increase of active sites give a higher pH response.\ud \ud Using the extended site-dissociation model, which describes the behaviour of a surface composed of two types of sites, theoretical curves for surface potential versus pH are calculated. Measurements with chemically-treated siO2 and Ta2O5 ISFETs confirm the theoretical expectations. The conclusion has been drawn that by a proper choice of chemical treatment, both the point of zero charge (pzc) and the pH-insensitive rage can be changed

Ion-sensing using chemically-modified ISFETs

Synthetic macrocyclic polyether ion receptors are the active components for the selective and sensitive detection of potassium ions in chemical sensors based on modified ISFETs.\ud \ud Covalent chemical anchoring of the sensing membrane to the gate oxide of the ISFET is essential in order to increase the lifetime of the sensor system to more than three months

Chromoionophores in optical ion sensors

The feasibility of surface plasmon resonance (SPR) for ion sensing has been investigated. Emphasis is laid on a simulation-based optimization of the SP carrying structure, as well as the applicability of a specific chemo—optical interface we have developed. A preliminary result is presented

Ervaren chemie: Chemie ervaren

Applied Science

Method for manufacturing a film of arylalkyl-modified polyacetylene, said polyacetylene obtained, and the use thereof

The present invention relates to a method of manufacturing a film of arylalkyl-modified polyacetylene, wherein a layer of an arylalkyldiacetylene compound with the formula (I): X(N)-L-CC-CC-L-(N)X wherein X(N) represents a nitrogen-containing planar aromatic group L represents a linear aliphatic group -(CH2)n- with