A low-shear-rate version of the BiODE solid-state ViSmart viscosity sensor instantaneously measures samples of fluids with low- to mid-range viscosities. The sensor provides continuous, real-time, in-line viscosity measurements for in-line process control systems that require high resolution and accuracy. The acoustic sensor measures 1.3 by 1.1 by 0.4 in. (see the figure) and weighs only 4 oz. Using robust and reliable semiconductor technology, it has no moving parts and is sealed, so it can be completely immersed in the process stream, where it would be unaffected by vibration or flow conditions. In addition to viscosity from 1 to 500 centipoise, the sensor simultaneously measures up to 125°C. It requires no field calibration. Testing confirmed the sensor's accuracy of 2%, reproducibility of 3%, and repeatability of 1%. Custom options and configurations are available for specific industry applications and process requirements.