Development and implementation of a system to measure the response of quartz crystal resonator based gas sensors using a field-programmable gate array

摘要

The development of gas sensors based on quartz crystal resonators requires the use of a frequency counter to measure the sensor response. However, commercial frequency counters have at most two channels, and in odour sensory systems (electronic noses), arrays of at least eight sensors are used. Furthermore, it is also desirable that the signal processing and data analysis stage can be included in the same system. A field-programmable gate array (FPGA) can provide a solution to these kinds of problems. This work involves the development of a system to measure the response of quartz crystal resonators, which is implemented using a high resolution frequency counter using an FPGA capable of processing and storing the data in 32-bit registers. Data transfer and acquisition were performed using a microcontroller. The virtual instrumentation software LabVIEW was used for the sensor response display and data storage in a computer. A frequency range from 0 Hz to 100 MHz with a resolution and stability of 1 Hz was achieved using a timebase of 1 s. Tests were performed using gas sensors to obtain real data. The system was escalated to four channels, verifying that it behaves in a correct and stable way.