¤ Results 2021

in Romanian

Development of the portable system

VOC-DETECT General diagram of the Smart system for VOCs detection

In the current phase of the project, the main functional elements of the portable system were identified and the block diagram was defined, then the components necessary for the implementation of each block were identified and the signal conditioning circuit was designed to interface the sensors with the programmable logic module.

The main functional elements of the portable system for the detection of volatile organic compounds are:
- electrical interface block for converting the sensor response into an easy-to-read electrical signal;
- the ability to acquire measurement data from sensors and their local storage;
- display of measurement results locally, the portable system having a touch display for user interaction;
- wireless communication capability, for remote accessibility and data transmission to a general database, independent of the portable system.

Based on these functionality considerations, the chosen solution is based on a Raspberry Pi 4 (RPi) single-board computer module, with the possibility of WiFi and Bluetooth connections, with a touch display attached to facilitate user interaction and presentation of results on the spot; to these modules is added a module that provides the digital-analog interface with the sensors, the module made on an independent printed wiring (PCB), designed to meet the particular requirements of the project.

Rasperry Pi 4 module for the portable system control logic implementation; touch screen  for local data display

The circuit that makes the electrical interface with the sensors is shown in the electrical diagram in figure 2.2 above. It comprises four blocks of signal conditioning, one for each sensor, the output signal of which is a voltage level inversely proportional to the resistance of the sensor, a relation expressed by the formula:
In the next stage, the resistance values ​​will be optimized so that the measurement range is optimal for each type of sensor developed in the project.

Also during this 3rd stage of the project, the preparation and deposition of sensitive materials for the detection of volatile organic compounds (formaldehyde, benzene) was performed. Morphological and structural characterizations of the deposited sensitive materials were also performed, as well as tests on the sensitivity of the deposited materials to volatile organic compounds.
The VOC-DETECT project continues in the next stage with the stage of testing and demonstrating the functionality of the integrated system.

The circuit that ensures the electrical interface with the sensors comprises four blocks of signal conditioning, one for each sensor, whose output signal is a voltage level inversely proportional to the resistance of the sensor, relation expressed by the formula:
In the next stage, the resistance values will be optimized so that the measurement range is optimal for each type of sensor developed in the project.
Also during this 3rd stage of the project, the preparation and deposition of sensitive materials for the detection of volatile organic compounds (formaldehyde, benzene) was performed. Morphological and structural characterizations of the deposited sensitive materials were also performed, as well as tests on the sensitivity of the deposited materials to volatile organic compounds.

The VOC-DETECT project continues in the next stage with the stage of testing and demonstrating the functionality of the integrated system.