Optimisation of a two-wire thermal sensor for flow and sound measurements

Honschoten van, J.W. and Krijnen, G.J.M. and Svetovoy, V.B. and Bree de, H.E. and Elwenspoek, M.C. (2001) Optimisation of a two-wire thermal sensor for flow and sound measurements. In: 14th IEEE International Conference on Micro Electro Mechanical Systems, MEMS, 21-25 Jan. 2001, Interlaken, Switzerland.

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Abstract:	The Microflown is an acoustic sensor measuring particle velocity instead of pressure, which is usually measured by conventional microphones. In this paper an analytical model is presented to describe the physical processes that govern the behaviour of the sensor and determine its sensitivity. The Microflown consists of two heaters that act simultaneously as sensors. Forced convection by an acoustic wave leads to a small perturbation of this temperature profile, resulting in a temperature difference between the two sensors. This temperature difference, to which the sensitivity is proportional, is calculated with perturbation theory. Consequently the frequency dependent behaviour of the sensitivity is analysed; it is found that there are two important corner frequencies, the first related to the time constant velocity of heat diffusion between the sensors, the second related to the heat capacity of the heaters. The developed model is verified by experiments. Previously a very good model has been given for the performance of the Microflown in a channel, i.e. with both heaters between fixed walls walls in the positive and negative z-direction. Here, a model is presented that describes the situation of the present used sensors: without walls under and above them. Model predictions are compared to experimental results
Item Type:	Conference or Workshop Item
Copyright:	© 2001 IEEE
Faculty:	Electrical Engineering, Mathematics and Computer Science (EEMCS)
Research Group:	Transducers Science and Technology (TST)
Link to this item:	http://purl.utwente.nl/publications/42033
Official URL:	http://dx.doi.org/10.1109/MEMSYS.2001.906594
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