VAMP: Voltammetric autonomous measuring probes for trace metals in the water column and at water-sediment interfaces

• Research unit: EU RFP
• Project number: 95.0369-2

Key words (English)

Iridium; mercury-film microelectrodes; trace metal analysis; environmental measurements; thin-film technology; microdisk arrays

Alternative project number (English)

EU project number: MAS3-CT95-0033

Research programs (English)

EU-programme: 4. Frame Research Programme - 3.2 Marine sciences and technologies

Short description (English)

See abstract

Partners and International Organizations (English)

CABE, University of Geneva (CH), Idronaut SrI (I), AMK, University of Göteborg (S)

Abstract (English)

Two types of voltammetric probes for in situ trace metals measurements have been developed within the project. The first one, for the water column measurements and the second, more complex, for the profiling at the water/sediment interfaces. Both of these probes rely on Ir microelectrode arrays realised using thin4ilm microfabrication technology. Basic element of these arrays is an lr microdisk of 5 mm diameter arranged either in 5 x 20 interconnected microdisks geometry or in 64 individually addressable groups of three microdisks each. Moreover both types of arrays are surrounded by a containment ring made of SU - 8 epoxy deposited and patterned on a wafer level and the latter comprises on-chip reference and counter electrodes.
Established initially for the 5 x 20 interconnected array and thoroughly evaluated for the subsequent Hg-thin film deposition with respect to the reproducibility and stability of Hg-layers, the same technological parameters have been used for the fabrication of the more complex lr microdisk array tor the waterisediment interface profiling. This consists of an array of 64 groups of individually addressable microelectrodes, each group comprising a set of three interconnected microdisks. The spacing between the lines no 1 to 23 decreases from 2000 mm to 220 mm and the remains at 200 mm between the lines 23 to 32. The geometry of the lines 33 to 64 is mirror image of that for the lines 1 to 32. This design has been chosen to allow concentration profiles over a total length of 4 cm to be measured. The on chip reference and counter electrodes are completing the sensor. The epoxy containment ring 300 ~m thick has been subdivided in 9 compartments in order to minimise the internal stress ot both the ring and the subsequently deposited protective agarose gel. The chip (9 mm x 42 mm) is mounted on a specially developed 4 layers printed circuit board (PCB) featuring a penetrating tip ot ca. 160 mm.
In parallel we have participated in the development of the voltammetric probe hardware by designing and realising the first unit of the voltammetric probe analogue board. This unit consists ot 64 preamplifiers and 8 multiplexers and it is directly connected to the sensor PCB.

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: 95.0369-2