Volatile organic compounds (VOCs) are gases emitted by various products, including paints, pharmaceuticals, and refrigerants, which can have harmful effects on health. They also serve as indicators for explosives, insect infestation, food spoilage, and diseases.
Detecting and tracing VOCs is crucial for public safety and addressing odor-related concerns. Liu and colleagues have developed a new design for an electronic nose (e-nose) that employs fluid mechanics principles to consistently detect VOCs at low concentrations. Their approach involves utilizing a shunt-like device to control the behavior of fluid flow, representing a significant advancement in e-nose technology. Their study, titled “Controlling fluidic behavior for ultrasensitive volatile sensing,” was recently published in Applied Physics Reviews on May 23, 2023.
Detecting VOCs poses numerous challenges, including selectivity, sensitivity, reproducibility, and stability. E-noses, inspired by the human olfactory system, offer a solution by combining arrays of chemical sensors with pattern recognition techniques to identify odors.
However, many e-noses exhibit variations in signal responses to VOCs of the same concentration when the sensor is placed in different regions of the “nose” chamber.
Author Weiwei Wu explains, “To address this issue, it is essential to precisely control the fluidic behavior of gas flow, ensuring a uniform fluidic field and VOC concentration within the chamber, thereby eliminating any spurious sensing characteristics.”
The initial e-nose design comprises a vertical chamber resembling a showerhead, facilitating vertical gas flow as it spreads through holes at the device’s base and reaches evenly distributed sensors.
By employing fluid mechanics simulations, the research team optimized the chamber’s volume, symmetry, hole placement, and sensor locations. They introduced a shunt-like device to enhance fluid flow and reduce response time.
Based on simulation results, the researchers constructed a Teflon chamber and evaluated the e-nose’s sensing performance. They compared two chambers—one with the shunt device and one without. The chamber featuring the shunt consistently outperformed the other, achieving approximately 1.3 times better sensing of a sample VOC.
In the future, the authors intend to focus on further reducing response and recovery times by refining the chamber design and structure.
“E-nose research requires a highly interdisciplinary approach,” emphasizes Wu. “Chemists, physicists, biologists, electronics engineers, and data scientists must collaborate to address various issues, such as effective sensing that considers the fundamental mechanisms of absorption and desorption, developing algorithms for rapid and precise VOC recognition with lower energy consumption, and exploring the integration of emerging technologies like memristors.”
Source: American Institute of Physics
