Hardware Design for Low Power Integrated Sensor System

Maher Rizkalla, An Feng, Michael Knieser, Francis Bowen, Paul Salama, Brian King, Jasmin Radadia, Sarang Gadkari, Hossein Jafarian

CSIRO Department of Electrical and Computer Engineering, Purdue School of Engineering and Technology, Indiana University Purdue University Indianapolis, Indianapolis, USA.
CSIRO Department of Electrical and Computer Engineering, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, USA.
Smart Systems Technology Inc., Loveland-Madeira Corridor, USA.

DOI: 10.4236/ijcns.2012.53018                

Abstract

An integrated sensor system is implemented using inter-integrated circuit mode (I2C) software, utilizing the PIC182585 MPLAB embedded control system utilizing hardware. The hardware implementation features high level of integration, reliability, high precision, and high speed communications. The system was demonstrated by temperature and CO₂ sensors. An extension for Zigbee system is proposed to enhance the security of the integrated system. A bi-directional air/liquid flow sensor is also added to detect the flow magnitude and direction that can be applied to heating, ventilating, and air-conditioning (HVAC), local and national security within subway systems, and medical equipment. The hardware design of the flow sensor included one heating element and two sensing elements to detect the bi-directional flow. Platinum sensors were found to be of high sensitivity and linear characteristics within 0℃ to 100℃ range, and their high temperature coefficient (0.00385 Ω/Ω/℃). Polyimide thin film heater was used as the heating element due to its high throughput and good thermal efficiency. Two bridge circuits were also designed to sense the temperature distribution in the vicinity of the sensing elements. Three high precision instrumentation low power amplifiers with offset voltage ~2.5 μV (50 μV max) were used for the overall design. The system security is also enhanced with the detection of poison gas using Carbon Nanotube devices (CNT). An antenna system was designed, and a frequency shift was detected to designate the type of poison gas used for a general threat.

Keywords

Smart Sensors; Embedded Systems; HVAC; PIC18 Microprocessor; I2C Bus; Bidirectional Airflow; Wireless

Conflicts of Interest

The authors declare no conflicts of interest.

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