A lift force sensor with integrated hot-chips for wide range flow measurements

摘要

The lift force gas flow sensor uses the force normal to the fluid flow to measure the flow velocity. Two thin plates mounted at an angle are deflected when they are subjected to fluid flow. By combining the mechanical lift force sensor and a thermal hot-chip sensor we now have obtained a sensor capable of high sensitivity in both high and low flows. Both the thermal and the non-thermal parts of the flow sensor have non-linear flow dependencies leading to a flow dependent sensitivity where the hot-chip part has its highest sensitivity for low flows and the lift force part has its highest sensitivity for high flows. When connected in an acceleration insensitive bridge configuration, the lift force sensor is basically insensitive to the direction of the flow but combined with a dual hot-chip configuration, bi-directionality has been accomplished. Here this has been shown by measuring the magnitude using the mechanical lift force principle and using a dual hot-chip configuration for direction detection. This is demonstrated in a simulated ventilator measurement. (C) 2003 Elsevier B.V. All rights reserved. [References: 8]