Direct measurement of the adhesive strength of biofilms in pipes by micromanipulation

A novel micromanipulation technique has been developed to measure directly the adhesive strength of biofilms formed in pipe flows. A T-shaped probe wa s specially designed to pull Pseudomonas fluorescens biofilms away from the inner surface of a pipe to which they were attached. The adhesive strength between biofilms and the substratum was defined as the work required to re move the biofilms per unit area from the substratum. Results showed that th e adhesive strength increased with the fluid velocity in which the biofilms were grown, with a typical value of 0.05 similar to 0.2 J/m(2).