Micro Coriolis mass flow sensor for chemical micropropulsion systems

We have designed a micromachined micro Coriolis flow sensor for the measurement of hydrazine (N2H4, High Purity Grade) propellant flow in micro chemical propulsion systems [1]. The sensor measures mass flow up to 6 mg/s for a single thruster or up to 24 mg/s for four thrusters. The sensor will first be used for measurement and characterization of the micro thruster system in a simulated space vacuum environment. Integration of the sensor chip within the micro thruster flight hardware will be considered at a later stage. The new chip has an increased flow range because of an integrated on-chip bypass channel

Micro Coriolis mass flow censor with extended range for a monopropellant micro propulsion system

We have designed and realised a micromachined micro Coriolis flow sensor for the measurement of hydrazine (N2H4, High Purity Grade) propellant flow in micro chemical propulsion systems. The sensor should be able to measure mass flow up to 6 mg/s for a single thruster or up to 24 mg/s for four thrusters. The sensor will first be used for measurement and characterisation of the micro thruster system in a simulated space vacuum environment. Integration of the sensor chip within the micro thruster flight hardware will be considered at a later stage. The new chip has an increased flow range because of an integrated on-chip bypass channel. First measurement results have demonstrated an increase in flow range which corresponds well to the designed bypass ratio

Micro Coriolis Mass Flow Sensor with Piezoelectric Transducers for Both Actuation and Readout

We have realized a micro Coriolis mass flow sensor with piezoelectric transducers for both actuation and readout, resulting in lower power consumption and improved robustness to shock in comparison to the current actuation and readout methods. The PZT thin film in the parallel plate piezoelectric transducers was deposited by pulsed laser deposition (PLD). This paper presents the design, fabrication process and initial characterization results with mass flow of water and nitrogen.</p

Integrated pressure sensing using capacitive Coriolis mass flow sensors

The cross-sectional shape of microchannels is, dependent on the fabrication method, never perfectly circular. Consequently, the channels deform with the pressure, which is a non-ideal effect in flow sensors, but may be used for pressure sensing. Multiple suspended channels with different lengths were modeled, fabricated, and characterized to verify the use and the scalability of this effect for pressure sensing. Furthermore, it is shown that the pressure dependence can be distinguished from the Coriolis effect in microfabricated Coriolis mass flow sensors, enabling the measurement of the pressure next to flow and density with only the flow sensor itself. In addition, this allows for further improvement in the accuracy of the flow measurement by correcting for the small pressure dependence

A compact micro Coriolis mass flow sensor with flow bypass for a monopropellant micro propulsion system

We have designed, fabricated and tested a micromachined Coriolis flow sensor for the measurement of hydrazine (N2H4) propellant flow in a micro chemical propulsion system (uCPS). The sensor will be used for measurement and characterization of the uCPS in a simulated space vacuum environment. To reach the required flow range a bypass system is integrated. Initial measurements demonstrate an increase of the flow range in accordance with the designed bypass ratio. The sensor is operated as a two-port resonator in an oscillator circuit to improve frequency stability

A novel capacitive detection principle for Coriolis mass flow sensors enabling range/sensitivity tuning

We report on a novel capacitive detection principle for Coriolis mass flow sensors which allows for one order of magnitude increased sensitivity. The detection principle consists of two pairs of comb-structures: one pair produces two signals with a phase shift directly dependent on the mass flow, the other pair is used to cancel the actuation signal. This results in larger phase shifts for the same mass flows. The range and sensitivity of the sensor can be tuned by changing the amount of cancellation of the actuation frequency, e.g. the size ratio between the comb-pairs