Low-Drift Flow Sensor with Zero-Offset Thermopile-Based Power Feedback
Abstract
A thermal flow sensor has been realised consisting of freely-suspended silicon-rich silicon-nitride microchannels with an integrated Al/poly-Si++ thermopile in combination with up- and downstream Al heater resistors. The inherently zero offset of the thermopile is exploited in a feedback loop controlling the dissipated power in the heater resistors, eliminating inevitable influences of resistance drift and mismatch of the thin-film metal resistors. The control system cancels the flow-induced temperature difference across the thermopile by controlling a power difference between both heater resistors, thereby giving a measure for the flow rate. The flow sensor was characterised for power difference versus water flow rates up to 1.5 ul/min, being in good agreement with a thermal model of the sensor, and the correct low-drift operation of the temperature-balancing control system has been verified.
Cite
@article{arxiv.0805.0891,
title = {Low-Drift Flow Sensor with Zero-Offset Thermopile-Based Power Feedback},
author = {M. Dijkstra and T. S. J. Lammerink and Meint De Boer and J. W. Berenschot and Remco Wiegerink and M. Elwenspoek},
journal= {arXiv preprint arXiv:0805.0891},
year = {2008}
}
Comments
Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/handle/2042/16838)