Graduation Year
2025
Document Type
Thesis
Degree
M.S.E.E.
Degree Name
MS in Electrical Engineering (M.S.E.E.)
Degree Granting Department
Electrical Engineering
Major Professor
Arash Takshi, Ph.D.
Committee Member
Sylvia Thomas, Ph.D.
Committee Member
Ehsan Sheybani, Ph.D.
Keywords
Auto Ranging Circuit, Chemiresistor, Electronic Nose, Interdigitated Electrode, Thin Film Sensor
Abstract
This thesis presents the development, characterization, and integration of a novel low-cost, high-dynamic-range sensor platform for the detection of volatile organic compounds (VOCs), leveraging the unique electrical properties of carbon nanotube (CNT) thin films. The platform introduces a fully integrated auto-ranging analog front-end circuit capable of real-time resistance measurement spanning over eight orders of magnitude ranging from tens of ohms to hundreds of megaohms, without compromising signal resolution or precision. This was achieved through a digitally controlled, multi-path feedback architecture and controllable current source.
To further enhance sensor performance, the system incorporates a copper trace heater beneath the sensor array, allowing programmable thermal modulation via PWM control. This heater accelerates sensor recovery and enables temperature-programmed analyte discrimination. The platform also integrates environmental monitoring via an HTU21D sensor for real-time temperature and humidity logging, ensuring the accuracy and repeatability of experiments.
Sensor fabrication involved drop-casting multi-walled CNT (MWCNT) dispersions onto three custom-designed interdigitated and gapped electrode geometries. Electrical and thermal tests confirmed stable and reproducible sensor responses to ethanol vapor, with the heater significantly reducing recovery time.
Altogether, this work demonstrates a flexible, scalable, and highly customizable VOC sensing platform that combines hardware adaptability with signal processing capability. Its compact architecture and modular design lay the foundation for future development in smart sensing systems, material optimization studies, and multi-analyte detection.
Scholar Commons Citation
Kalach, Thomas, "An Integrated PCB-Based Heating and Auto-Ranging Platform for Volatile Organic Compound (VOC) Detection Using Carbon Nanotube Based Sensors" (2025). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/11057
