Ambient Temperature-Gradient Compensated Low-Drift Thermopile Flow Sensor

Author

Dijkstra, Marcel ; Lammerink, T.S.J. ; de Boer, M.J. ; Wiegerink, R.J. ; Elwenspoek, M.

Author_Institution

MESA+ Inst. for Nanotechnol., Univ. of Twente

fYear

2009

fDate

25-29 Jan. 2009

Firstpage

479

Lastpage

482

Abstract

A highly-sensitive thermal flow sensor for liquid flow with nl-min^-1 resolution has been realised. The sensor consists of freely-suspended silicon-rich silicon-nitride microchannels with integrated Al heater resistors and Al/poly-Si⁺⁺ thermopiles. The influence of drift in the thin-film metal resistors is effectively eliminated by using thermopiles combined with an adequate measurement method, where the power in the heater resistors is controlled, e.g. constant-power calorimetric method or temperature balancing method. The special meandering layout of the microchannels and the placement of thermopile junctions increases sensitivity by summing the thermopile voltages due to convection by fluid flow, whereas the influence of ambient temperature gradients is compensated for.

Keywords

aluminium; calorimeters; convection; flow sensors; microchannel flow; microsensors; silicon; silicon compounds; thermopiles; Al; Si; Si₃N₄; aluminium-polysilicon thermopile; constant power calorimetric method; drift effects; fluid convection; freely suspended silicon nitride microchannels; heater resistor power control; integrated aluminium heater resistors; low drift capability; meandering microchannel structure; temperature balancing method; temperature gradient compensation; thermopile flow sensor; thermopile junction location; thermopile voltage; thin film metal resistors; Cogeneration; Fluid flow; Fluid flow control; Microchannel; Power measurement; Resistors; Temperature control; Temperature sensors; Thermal sensors; Transistors;

fLanguage

English

Publisher

ieee

Conference_Titel

Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on

Conference_Location

Sorrento

ISSN

1084-6999

Print_ISBN

978-1-4244-2977-6

Electronic_ISBN

1084-6999

Type

conf

DOI

10.1109/MEMSYS.2009.4805423

Filename

4805423