The viscoelastic properties of fluids are key to their performance in industries ranging from biotechnology to the automotive industry. Traditionally, fluid viscoelastic properties are monitored with rheometers but these are expensive, require a skilled operator, function over a relatively limited frequency range and are not suitable for in situ monitoring. Piezoelectric cantilevers capable of in situ assessment of the rheological properties of relatively small fluid volumes have the potential to overcome many of these limitations and can be fabricated into low cost probes. Rheological assessment of test fluids using piezoelectric cantilevers is typically made through analysis of the cantilever's resonant oscillation in the fluids. For accurate results, the damping of the cantilever should be low as quantified by a high quality factor Q. This can be difficult in fluids of high viscosity particularly for microscopic cantilevers. In this paper, a "mesoscale" piezoelectric bimorph cantilever was used. The mesoscale refers to a size regime intermediate between microscopic and macroscopic, in this work the cantilever used has dimensions of the order of millimeters. This mesoscale cantilever displayed a sufficiently high Q to probe the rheological properties of highly damping and elastic fluids in situ. The developed probe will be ideally suited to in-process monitoring of high value products such as those in the biotechnology industry. (C) 2012 The Society of Rheology. [DOI: 10.1122/1.3670732]