DocumentCode :
2688413
Title :
Characterization of the thermal transients of an Ultra Low Power micromachined sensor
Author :
Rastrello, F. ; Placidi, P. ; Bissi, L. ; Scorzoni, A. ; Cozzani, E. ; Elmi, I. ; Zampolli, S. ; Cardinali, G.C.
Author_Institution :
DIEI, Univ. of Perugia, Perugia, Italy
fYear :
2010
fDate :
3-6 May 2010
Firstpage :
1591
Lastpage :
1595
Abstract :
This paper describes an embedded system for the simultaneous dynamic control and thermal characterization of the heating phase of an Ultra Low Power (ULP) micromachined sensor, featuring thermal characteristics quite similar to those of innovative ULP semiconducting metal oxide (MOX) sensors. A Pulse Width Modulated (PWM) powering system has been realized using a microcontroller featuring an ARM7 core to characterize the thermal behavior of a device formed by a Pt microheater and a Pt temperature sensor, over an insulating membrane. Two operating modes, namely constant target heater resistance and constant heating power, were implemented. The aim was to analyze the relation between heating period and operating temperature, to observe the thermal time constants of the device and the total thermal conductance. Repeatability of experimental results was assessed by guaranteeing the standard deviation of the controlled temperature was within ±5.5°C in worst case conditions. Experimental results show quantitatively a unique time constant τ both for the heater and the T-sensor, that changes dependently on the temperature rise ΔT between the ambient and the operating temperature in a range from 2 ms to 2.4 ms. The dependence of the operating temperature of such ULP micromachined systems on the frequency and duty cycle of the PWM signal was also characterized and guidelines for minimizing the temperature ripple were defined. Finally, we observed that in the chosen operating temperature range the thermal conductance is a linear function of the heating power.
Keywords :
embedded systems; gas sensors; heat conduction; low-power electronics; microcontrollers; microsensors; temperature control; temperature sensors; ARM7 core; Pt; constant heating power; constant target heater resistance; dynamic control; embedded system; gas sensor; heating phase; microcontroller; microheater; pulse width modulated powering system; temperature sensor; thermal conductance; thermal transients; ultra low power micromachined sensor; Heating; Pulse width modulation; Sensor phenomena and characterization; Sensor systems; Temperature control; Temperature dependence; Temperature distribution; Temperature sensors; Thermal conductivity; Thermal sensors; ARM processor; Gas Microsensor; MOX sensor; Microheater; Temperature Dependence; Thermal Transient Response; ULP;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Instrumentation and Measurement Technology Conference (I2MTC), 2010 IEEE
Conference_Location :
Austin, TX
ISSN :
1091-5281
Print_ISBN :
978-1-4244-2832-8
Electronic_ISBN :
1091-5281
Type :
conf
DOI :
10.1109/IMTC.2010.5488153
Filename :
5488153
Link To Document :
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