CONSENSUS: Continuous monitoring of chemical parameters using single-use sensor systems

• Research unit: EU RFP
• Project number: 99.0331

Key words (English)

Single-use sensors; oxygen sensor; microelectrode arrays; environment

Alternative project number (English)

EU project number: G6RD-1999-00171

Research programs (English)

EU-programme: 5. Frame Research Programme - 1.3.8 Generic R&D activities

Short description (English)

See abstract

Partners and International Organizations (English)

Coordinator: Unilever (UK)

Abstract (English)

The objective of the 'Consensus' project was to realize a prototype of a novel chemical sensing instrument, to be used for online monitoring of analytes in liquids. The basic principle is the use of a novel format based on a tape including a sequence of more than 1000 single-use sensors in order to achieve a reliable, cost effective monitoring system without need for calibration and that requires little maintenance. Appropriate electrochemical and colorimetric methods were developed for monitoring the concentration of a number of analytes including a photographic colour developer, iron, linear alkyl surfactants, pH and dissolved oxygen. Both optical and electrochemical versions of the tape have been produced in suitable length. The instrument prototype includes a small volume sample flow cell (approx. 100 Ill), the control mechanism for tape advancement and positioning and a voltammetric analyser.
CSEM aimed at the development of a simple, membrane-less, electrochemical sensor based on the use of microelectrode arrays integrated on silicon chips. The chip design and the low fabrication cost of the arrays are compatible with a single use sensor concept for a number of applications. Chip integration on the Consensus tape was demonstrated.
The developed analytical method was focused on dissolved oxygen. The achieved detection limit, linearity, repeatability are in good agreement with the requested values for activated sludge control. The problem of activated sludge sampling could however not be solved within the project and the method was adapted for an array being directly immersed in the sludge. A field test in a wastewater treatment plant demonstrated a stable array sensitivity of more than one week. Further work will be necessary to address either the sludge sampling or more realistically the automated replacement of the 'in-situ' sensing array. Monitoring of 'active oxygen', i.e. peroxides used as disinfecting or bleaching agents, was also investigated within the Consensus project. The results obtained for hydrogen peroxide and peracetic acid indicate that integration of the method on a tape format could be realized without major difficulty.
Due to its versatility microelectrode arrays could be a major asset for the Consensus instrument, not only for dissolved oxygen, but also for disinfectant monitoring, heavy metal detection and other electroanalytical applications. Results and know-how obtained within the project will also help the development of innovative hand-held single use sensors as well as under favourable situations on-line continuous monitoring sensors.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 99.0331