Low-Drift flow sensor with zero-offset thermopile-based power feedback


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Dijkstra, M.A. and Lammerink, T.S.J. and Boer, M.J. de and Berenschot, J.W. and Wiegerink, R.J. and Elwenspoek, M.C. (2008) Low-Drift flow sensor with zero-offset thermopile-based power feedback. In: Proceedings of DTIP, 9-11 Apr 2008, Nice (pp. p. 4).

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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 μl·min-1, 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.
Item Type:Conference or Workshop Item
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Electrical Engineering, Mathematics and Computer Science (EEMCS)
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Link to this item:http://purl.utwente.nl/publications/65251
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