Title :
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
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;
Conference_Titel :
Micro Electro Mechanical Systems, 2009. MEMS 2009. IEEE 22nd International Conference on
Conference_Location :
Sorrento
Print_ISBN :
978-1-4244-2977-6
Electronic_ISBN :
1084-6999
DOI :
10.1109/MEMSYS.2009.4805423
