Biosensors & Bioelectronics Vol. 11 No. 10 (1996)

The 4th New Zealand Symposium on Chemical and Biosensors

4 - 5th June 1996

Alan Hart

Though considered by some to be geographically distant, antipodean scientific meetings lack for nothing in their content, relevance and speakers. This report is a taster of what can be expected at meetings to be held in the southern hemisphere.

Many sensor scientists have felt there is a certain art in getting sensors to work, so it was perhaps appropriate that this symposium was held in the rico-Gothic buildings of the Arts Centre of Christchurch. The Arts Centre provided an elegant, yet cosy venue for this congenial meeting attended by scientists from New Zealand, Australia, USA and the United Kingdom.

Of the 26 presentations (papers and posters), 13 were on biosensors, eight on chemical sensors, 4 on physical or biophysical sensing techniques and one other on the assessment of ecosystem health. This last-rnentioned presentation was an interesting account of the application of biochemical tests, derived from clinical chemistry, to vertebrate and invertebrate animals. The results of these tests are used to provide early warnings of possible future ecosytem damage from xenobiotic compounds. The speaker hoped that sensor researchers would be able to develop suitable in vitro test systems to replace the use of whole organisms as environmental markers.

Screen-printing as a means ofbiosensor production was well-represented in presentations by scientists from New Zealand and the United Kingdom; the speaker from the United Kingdom gave an exemplary account of a sensor which had been

developed in the light of market research and discussions with an end-user. The other main technique for construction of biosensors discussed - principally by Australian delegates - at the symposium was the use of conducting polymers. Conducting polymers had also been used to make dmnieal ion and gas sensors. It was suggested, by a New Zealander, that the performance of conducting polymer sensors could be improved by monitoring the development of the polymer by changes in resistance rather than by passing a particular quantity of charge. A commercially available odour sensor, based on conducting polymers, was demonstrated. There was keen interest in this demonstration, as it was an example of seining technology which had been brought onto the market - something which a great many sensing scientists around the world are required to aspire to.

Electrochemists at the symposium reminded delegates of their ability to make sensors without using biological molecules, and also of the contribution they can make in explaining phenomena which underlie many biosensors.

A biophysicist showed how, by careful attention to, and control of, physical parameters governing the behaviour of electrodes, impedance spectroscopy

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Blosensors & Bioelectronics Vol. 11 No. I0 (1996)

can be used to monitor biological properties of organisms. The interpretation of imlxxtance measurements can be aided, by data on the transport of ions across membranes using patch clamp techniques - data from tomatoes was used to illustrate this point by another speaker.

The use of whole cells in biosensors may yet prove to be feasible and practical. Prospects for the use of freeze-dried bacteria in BOD sensors were discussed, as was the behaviour of bacteria, genetically engineered to emit fight in the presence of analytes, in matrices designed to maintain them in a viable state.

This meeting was the last in its present form. The meetings 'down under' will continue in the form of a combined meeting of scientists from New Zealand and Australia - others are most welcome, of course. The first meeting in the new series will be in December 1997. It will be in New Zealand (exact venue to be decided) and organised from Australia! Watch out for the notices!

Contact: Dr Alan Hart, AgResearch Grasslands (Sensors Group), Private Bag 11008, Palmerston North, New Zealand, tel: [64] 6 356 8019, fax: [64] 6 351 8042, email: HartA@ Agresearch.cri.nz

Apart from providing an opportunity for scientists to meet and discuss their work, what the symposium showed most of all, was that sensor research is well established in New Zealand and Australia. There was a good balance of pure and applied work - most of the presentations were concerned with analysing real samples or motivated by the desire to do so.

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