Why we use microsensors

Dirk DeBeer, Ph.D.
Max Planck Institute for Marine Microbiology

Friday, August 3, 2001
12:00 Noon–Pacific Forum

Microsensors are needle type sensors with tips from 1 micron to 20 microns in diameter. With these devices a range of compounds can be measured. Most relevant for microbial ecology are O₂, pH, H₂S, Ca²⁺, CH₄, CO₂, NH₄, NO₃^-, and NO₂^-. Due to the small tips, disturbance is minimal and spatial resolution is optimal. The response times are usually in the order of seconds. We use microsensors to study (micro) biological activities on and inside interfaces. Examples are marine and freshwater sediments, biofilms covering solid surfaces, microbial mats, corals and calcifying algae, and burrowing fauna. The processes we focus on are photosynthesis, calcification, sulfate reduction, sulfide oxidation, nitrification, and denitrification.

The microanalyses allow, in principle, two types of studies. First, conversion rates can be measured, which allows budget studies in ecosystems. Second, the fast response times and highly localized nature of the measurements allow studies about the mechanisms of processes.

Two studies will be presented. A study on mineralization rates in intertidal sediments shows that direct measurement with microsensors is a unique and convincing method. Another study will be presented on the mechanism of calcification in corals and calcifying algae.

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