Towards system-level modeling and characterization of components for intravenous therapy

Problems occur regularly with intravenous therapy, especially with the flow behavior. A mechanical model can predict which components of intravenous therapy systems introduce non-ideal effects in the flow. This study concentrates on gaining quantitative information of each separate component for intravenous therapy, characterize its non-ideal effects and combine these quantities in one system-level model. The model will help in the development of a mass flow sensor which can be used in a control system for intravenous therapy

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

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

Inline pressure sensing mechanisms enabling scalable range and sensitivity

We report on two novel capacitive pressure sensing mechanisms that allow measurements inline with other fluidic devices on one chip, without introducing a large internal volume to the fluid path. The first sensing mechanism is based on out-of-plane bending of a U-shaped channel and the same structure could be used for thermal flow sensing simultaneously. The second mechanism is based on deformation of the cross-section of the tube and allows for differential capacitive readout. The sensitivity and range of both mechanisms are scalable. The current implementations are tested up to 2.45 bar and 1 bar respectively

Vortex generation and sensing in microfabricated surface channels

We realized a structure that is able to generate vortices inside a microfluidic channel. The structure is compatible with surface channel technology, enabling integration with other devices on the same chip. Characterization of the structure is done by scanning the top membrane of the channel using laser Doppler velocimetry. A novel method for finding the phase relation between the incoherent measured scan points is developed. Initial measurements show that the structure is able to act as a vortex flow sensor, since the vortex frequency is dependent on the flow velocity, making this the first microfluidic vortex flow sensor with a characterized range from 735 mg/h to 1335 mg/h with a sensitivity of 100 Hz/(mg/h). The structure can also be used for passive mixing

A Large Range Multi-Axis Capacitive Force/Torque Sensor Realized in a Single SOI Wafer

A silicon capacitive force/torque sensor is designed and realized to be used for biomechanical applications and robotics. The sensor is able to measure the forces in three directions and two torques using four parallel capacitor plates and four comb-structures. Novel spring and lever structures are designed to separate the different force components and minimize mechanical crosstalk. The fabrication process is based on deep reactive ion etching on both sides of a single silicon-on-insulator wafer and uses only two masks making it a straight-forward and robust process. The sensor has a force range of 2 N in shear and normal direction and a torque range of more than 6 Nmm. It has a high sensitivity of 38 fF/N and 550 fF/N in shear and normal direction respectively

Improved capacitive detection method 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 three times increased sensitivity. Capacitive Coriolis mass flow sensors are normally read out by two electrodes that measure the ratio between the actuation mode and the Coriolis mode, which is induced by the mass flow. This ratio results in a phase shift between the two electrodes. By adding two additional read out electrodes, the actuation mode signal is partially canceled, allowing for higher sensitivity to the Coriolis mode, and thus larger phase shifts for the same mass flows. An analytical model is derived and corresponds with the measurements. It is also proven that the range and sensitivity of the sensor can be tuned by changing the size of the additional readout electrodes. This readout method does not increase the readout time