Micro Coriolis mass flow sensor with integrated resistive pressure sensors

We report on novel resistive pressure sensors, integrated on-chip at the inlet- and outlet-channels of a micro Coriolis mass flow sensor. The pressure sensors can be used to measure the pressure drop over the Coriolis sensor which can be used to compensate pressure-dependent behaviour that might occur and it can be used to calculate the dynamic viscosity of the fluid inside the channels

μ-Coriolis mass flow sensor with improved flow sensitivity through modelling of the sensor

In this paper we present μ-Coriolis mass flow sensor devices with improved flow sensitivity. An FEM model is set up which can estimate various parameters of a μ-Coriolis device such as resonance frequency, spring constants and Coriolis forces. These parameters are then used in an analytical model to determine flow sensitivity. The presented FEM model allows for fast simulation of these properties, enabling optimization by varying many dimensions and other properties of the designs and see their influence on flow sensitivity. Three devices have been fabricated based on simulation results. All have been characterized and a comparison was made between different devices and between measurement and simulation results. The model predicts the resonance frequencies with less than 10% error for all except 1 (out of 6) devices. The predicted sensitivities are within 6–40% accurate depending on the type of device. Flow sensitivity is improved approximately 4–11 times with respect to a reference device of typical dimensions

Magnetic field strength improvement for Lorentz actuation of a μ-Coriolis mass flow sensor

In this paper we present and compare three different magnet configurations for Lorentz actuation of a μ-Coriolis mass flow sensor. The first configuration consists of 2 cylindrical magnets, the second is based on a Halbach ring, and the third configuration consists of a single cubic magnet. The magnetic field strength of each configuration is simulated. The Halbach configuration shows a magnetic field strength of 0.3 T, the single cubic configuration reaches 0.25 T. The two cylindrical magnets have the lowest field with 0.05 T. The stray field is significantly lower for the Halbach configurations compared to the other two configurations. All configurations were used for Lorentz actuation of a μ-Coriolis mass flow sensor and the frequency response was measured. The magnitude transfer between the actuation and induction voltages for the cubic and Halbach configurations show a transfer around 26 dB higher than the cylindrical configuration. The phase transfers for the Halbach and Cubical configurations are according to simulation. For the cylindrical configuration, the EMF signal is too weak to overcome the crosstalk between the actuation and induction voltages

A MEMS Coriolis Mass Flow Sensing System with Combined Drive and Sense Interface

This paper describes an interface circuit for a MEMS Coriolis mass flow sensor that combines both drive and sense circuitry. The MEMS sensor consists of a suspended resonant tube, which is read-out by comb capacitors and driven into oscillation by current flowing through a drive coil in a magnet field. The interface circuit comprises a low-noise front-end that performs capacitance-to-voltage (C/V) conversion, and a drive-loop with automatic amplitude control. Drive motion can also be detected from the output of the front-end, allowing both drive and sense functions to be combined. The front-end is chopped to mitigate its 1/ f noise. When implemented with commercial off-the-shelf (COTS) components, the proposed interface draws 250 mA from a single 5-V supply. Mass flow measurements with Nitrogen gas (N 2 ) show that the sensor's drive frequency drifts by less than 1 mHz (rms) per hour, while its zero stability is less than 2.6 mg/h during an 80s measurement