<p>A viscosity sensor for, e.g., outputting a signal representing the viscosity of engine oil has one or more piezoelectric diaphragms disposed in a fluid chamber (28) of a housing (20). An elongated amplification channel (30) is formed in the housing (20) and extends away from the chamber (28). The diaphragm can be excited to induce fluid movement that in turn induces the diaphragm to output a sensor signal representative of the viscosity of the fluid.</p>
