New MEMS-Based Micro-Coriolis Density Measurement Technology

Density measurements have long been used within the scope of process and product quality control in a variety of applications and industries. In the petroleum industry, measuring the density or specific gravity of liquid fuels has been reported to be the preferred method for both accuracy and ease of use, for example in blending operations. In the drinking water, beverage and pharmaceutical industries, density measurement is an important quality related fluid parameter. To see wide spread use, a measurement technology must not only be capable of accurately monitoring a parameter, but it must do so in an economical way. This paper explores laboratory and field hazardous area applications of a newly developed MEMS (Micro Electro Mechanical System) technology for density measurement. This microfluidic sensor, based on the Coriolis principle, has on-chip density / specific gravity, temperature and viscosity measurement capabilities, as will be demonstrated in the experimental results. These very compact MEMS devices are immune to vehicular vibration and have an extremely fast response time, due their high resonant frequencies. The ability to differentiate between types of fuels such as gasoline, ethanol, methanol, diesel, biodiesel, butanol, and to detect water and air contamination using density measurement, will be demonstrated. Concentrations of fuel blends such as E85 and others can be accurately determined. The density of liquid ingredients, additives and pharmaceutical liquids can be measured with high reproducibility. Measuring fluids under high flow rates is accommodated with an internal by-pass design. An intrinsically safe Class 1 Div 1 (or Zone 0) circuit has been developed to enable use of this technology with flammable liquids or in explosion hazardous atmospheres.