Design and Development of a Versatile Testing Setup for Volatile Organic Compound Sensors under Controlled Operating Conditions

Gas sensors are widely used in industrial, medical, and environmental applications for monitoring and quantifying gas molecules in ambient conditions. But, the absence of a dedicated characterization/testing setup limits comprehensive evaluation and development of gas sensors. This work presents the development of a cost-effective and multifunctional gas sensor testing setup using an Operational Amplifier (Op-Amp)-based electrical interfacing circuit, a multifunctional data acquisition (DAQ) card, a syringe pump, and a LabVIEW-based control program. Initial system calibration done using standard known resistors ({plus minus}1% tolerance) confirmed the setup's accuracy, with results closely matching those obtained from a Keithley DMM 2700, validating its reliability. The developed setup was tested with variable volatile organic compound (VOC) concentrations with controlled thermal conditions and fixed bias voltage operation to enable precise evaluation of gas sensors. To demonstrate its sensor characterization capability, three sensors using p- and n-type semiconductors were deposited on the fabricated Interdigitated Electrodes (IDEs). P-type sensor-1 and n-type sensor-2 evaluated V-I responses under varying VOC concentrations, revealing conductivity changes. Sensor-2 assessed thermal stability, showing staircase heating with minimal fluctuations. P-type sensor-3 examined time-dependent responses to ethanol, acetone, and toluene at room temperature, 50 {degree sign}C, and 100 {degree sign}C under a fixed bias, confirming the expected semiconducting behavior of the sensing material. These results demonstrate the VOC sensor testing setup as a robust platform for comprehensive gas-sensor characterization, enabling deeper insight into sensor behavior and advancing next-generation devices.