Browsing by Author "Gao, Bo"

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LOW-COST TEMPERATURE-COMPENSATED THERMORESISTIVE MICRO CALORIMETRIC FLOW SENSOR BY USING 0.35 mu m CMOS MEMS TECHNOLOGY
(2016)
Xu, Wei
;
Gao, Bo
;
Ma, Shenhui
;
Zhang, Anping
;
Chiu, Yi
In this paper, a low-cost Temperature-compensated Thermoresistive Micro Calorimetric Flow ((TMCF)-M-2) sensor by using a commercial 0.35 mu m 2P4M CMOS MEMS technology is reported. For nitrogen flow, the fabricated (TMCF)-M-2 sensor achieves a normalized sensitivity of 230 mV/(m/s)/mW with respect to the input heating power, which is two orders of magnitude better than the reported micro calorimetric flow sensors. The experimental results of (TMCF)-M-2 sensor under different ambient temperatures T-a of 22 degrees C similar to 48 degrees C showed the excellent temperature insensitive output with the maximum normalized variation of 0.5%. Compared to the uncompensated counterpart (49%), it demonstrates our robust (TMCF)-M-2 sensor design is applicable for the integration of on-chip CMOS electronics for the Internet of Things.
Packaging Effect on the Flow Separation of CMOS Thermoresistive Micro Calorimetric Flow Sensors
(2016-01-01)
Xu, Wei
;
Gao, Bo
;
Lee, Yi-Kuen
;
Chiu, Yi
;
電機工程學系
We systematically study the packaging effect on the performance of CMOS Thermoresistive Micro Calorimetric Flow (TMCF) sensors, including two types of sensor packaging designs: S-type and E-type. For S-type design, the experimental results indicate that not only the sensitivity of TMCF sensors was significantly changed by more than 30%, but also the flow range compared to the E-type design was dramatically reduced from 0 - 11 m/s to 0 -4.5 m/s. Comprehensive CFD simulations and the concise heater transfer analysis were performed to understand the physics behind these two different designs. Accordingly, a flow regime map (the protrusion vs the reduced Reynolds number) was constructed, where the critical boundary curve for the flow separation of CMOS TMCF sensors was determined. This flow regime map is a useful guideline for designing a well packaged flow sensor system.
Systematic study of packaging designs on the performance of CMOS thermoresistive micro calorimetric flow sensors
(2017-08-01)
Xu, Wei
;
Pan, Liang
;
Gao, Bo
;
Chiu, Yi
;
Xu, Kun
We systematically study the effect of two packaging configurations for the CMOS thermoresistive micro calorimetric flow (TMCF) sensors: S-type with the sensor chip protrusion-mounted on the flow channel wall and E-type with the sensor chip flush-mounted on the flow channel wall. Although the experimental results indicated that the sensitivity of the S-type was increased by more than 30%; the corresponding flow range as compared to the E-type was dramatically reduced by 60% from 0-11 m s(-1) to 0-4.5 m s(-1). Comprehensive 2D CFD simulation and in-house developed 3D numerical simulations based on the gaskinetic scheme were applied to study the flow separation of these two packaging designs with the major parameters. Indeed, the S-type design with the large protrusion would change the local convective heat transfer of the TMCF sensor and dramatically decrease the sensors' performance. In addition, parametric CFD simulations of the packaging designs provide inspiration to propose a novel general flow regime map (FRM), i.e. normalized protrusion d* versus reduced chip Reynolds number Re*, where the critical boundary curve for the flow separation of TMCF sensors was determined at different channel aspect ratios. The proposed FRM can be a useful guideline for the packaging design and manufacturing of different micro thermal flow sensors.
Theoretical and Experimental Investigations of Thermoresistive Micro Calorimetric Flow Sensors Fabricated by CMOS MEMS Technology
(2016-10)
Xu, Wei
;
Song, Kui
;
Ma, Shenhui
;
Gao, Bo
;
Chiu, Yi
A general 1-D model was presented to predict the characteristics of CMOS thermoresistive micro calorimetric flow (TMCF) sensor with two types of packaging, i.e., open-space type and channel type, for both gases and liquids. The 1-D model was first validated by a numerical computational fluid dynamics (CFD) model and was subsequently normalized for different fluids flow. Notably, the model proposed by Nguyen and Dotzel is a special case of our 1-D model. The normalized output of TMCF sensor is a function of normalized input parameters of Reynolds number Re and Prandtl number Pr. The scaling analysis of the sensor output, sensitivity, and power consumption was performed to optimize the design of TMCF sensors in terms of key design parameters, including the thin film thickness, the height of bottom cavity, and so on. Accordingly, three pairs of TMCF sensors were designed and fabricated by using a 0.35 mu m 2P4M CMOS microelectromechanical systems technology. The fabricated sensors showed a normalized sensitivity of 230 mV/(m/s)/mW for nitrogen gas flow, which was two orders of magnitude higher than the previous CMOS flow sensors. Therefore, the proposed 1-D model is a promising tool for the sensor\'s system-level design with the on-chip microelectronics for the Internet of Things. [2016-0098]