The precise, continuous monitoring of pollutants such as nitrogen oxides (NOx) in high humidity is a tough challenge for low-cost and stretchable gas sensors.
A recent article published in Microsystems & Nanoengineering describes the design and implementation of a novel, moisture-resistant, and wearable NOx gas sensor based on laser-induced graphene (LIG) that has proven successful in monitoring the environment and classifying individuals with breathing problems.
Importance of Nitrogen Oxides (NOx) Detection
Nitrogen oxides (collectively referred to as NOx) produced by combustion processes and petroleum refineries are significant air pollutants that cause bronchitis, asthma, and heart-aggravating disorders.
Nitric oxide (NO), a key biomarker for pulmonary inflammation, is of great relevance for the non-invasive detection and treatment of respiratory disorders such as lung cancer and ventilator-associated pneumonitis. This is because the level of nitric oxide in exhaled breath of asthma patients surpasses hundreds of parts per billion (ppb), but this amount is less than a few tens of ppb in healthy individuals.
Consequently, it is of the utmost significance to create new, inexpensive, and dependable gas sensors for continuously and precisely detecting nitrogen oxide (NOx) in human breath.
Wearable Graphene-based Gas Sensors for Detection of NOx
Several technologies using nanoparticles such as metal oxides, graphene, carbon nanotubes, and conductive polymers have been developed to detect NOx in human breath.
In contrast to the electrolytic cells, field-effect semiconductors and other conventional gas sensors, wearable NOx gas sensors based on graphene exhibit low noise and good mechanical robustness.
Wearable electronic devices can gather electrical, biochemical, thermal, physical, and biological information for comprehensive health management. The growing interest in personalized air quality assessment and breath testing has also increased the need for wearable graphene-based gas sensors that can detect different harmful chemicals, such as nitrogen oxides (NOx), precisely and continuously.
Graphene-based gas sensors with unmodified surfaces show low accuracy due to the absence of active sites. To tackle this issue, the newly discovered 3D laser-induced graphene (LIG) can be utilized because it provides a large number of active sites on the surface for gas-solid interactions.
Relative Humidity: A Major Limitation in Accurate Gas Sensing
As water particles populate the active surface functional sites of sensing nanomaterials, the relative humidity (RH) significantly affects the absorption and equilibrium mechanisms of the target gas, resulting in substantial response changes in breath samples with an RH between 50 and 95 percent.
The impact of relative humidity on gas sensing can be minimized by utilizing coated integrated heating components, hydrophobic self-assembled monolayers (SAMs), or electronic nose algorithms. However, these technologies often increase the sophistication and expense of gas sensor production.
Therefore, it is crucial to establish a simple method for designing and fabricating moisture-resistant NOx gas sensors with a large response rate, quick response/recovery, and a low limit of detection (LOD) for monitoring local air pollution and analyzing breath samples for disease diagnoses.
A Novel Moisture-Resistant LIG-based NOx Gas Sensor
In this study, the researchers created a novel, flexible, and moisture-resistant LIG-based NOx gas sensor by sandwiching the LIG sensing area between a semi-permeable polydimethylsiloxane (PDMS) layer and a flexible elastomeric platform.
The flexible, extremely sensitive, and selective LIG-based gas sensor is composed of a straight LIG sensing area and a serpentine electrode on a soft elastomeric platform. The LIG sensing region has a much narrower width (150 micro-meter) than the electrodes to produce substantially stronger resistance and concentrated Joule heating in the sensing zone,
The rapid and low-cost manufacturing method is also scalable, promising rapid large-scale production for commercial applications in the future.
Key Developments of the Research
At room temperature, the as-prepared gas sensor displays a high response rate, rapid response/recovery, and an ultralow limit of detection (LOD) for various nitrogen oxides (NOx). By adjusting laser processing parameters such as laser intensity, image frequency, and defocus distance, the laser direct writing method can produce LIG sensing zones with varying morphologies.
This unique water-resistant LIG-based gas sensor can detect the outside air quality at various times of the day by combining a high stretchability of 30 percent and a moisture-resistant capability against a relative humidity of 90 percent. In addition, it can promptly evaluate clinical breath samples to properly distinguish between patients with respiratory illnesses and healthy human beings.
News
Biopharma Creates New Generation LNPs In A Run For A More Efficient COVID-19 Vaccine
The COVID-19 pandemic highlighted the need for fast-produced and adaptable vaccines that could be equally distributed around the world. Developing an efficient mRNA vaccine that is effective, thermostable, and has fewer side effects strongly [...]
Researchers Assess How Well Machine Learning Predicts Nanotoxicology
Engineered nanomaterials (ENMs) have found their applications in various technologies and consumer products. Manipulating chemicals at the nanoscale range introduces unique characteristics to these materials and makes them desirable for technological applications. With the [...]
Smart nanoparticle shows that intermittent fasting may protect the heart from damage during chemotherapy
Although chemotherapy can be a lifesaving treatment for patients with cancer, some of these medications can damage the heart. A team led by researchers at Massachusetts General Hospital (MGH) recently developed a nanoparticle probe [...]
From nasal vaccines to pills: the next defences against Covid
When the autumn booster programme begins next month, many people are likely to receive Moderna’s new bivalent vaccine, designed to protect against the original Covid strain and the more transmissible Omicron variant. As Covid continues [...]
Novel design for nanoparticles that train immune cells into fighting cancer
Scientists of the department of Advanced Organ Bioengineering and Therapeutics (TechMed Centre) recently published a novel cancer immune therapy in the scientific journal Nature Communications ("Cancer immune therapy using engineered ‛tail-flipping’ nanoliposomes targeting alternatively activated macrophages"). [...]
Smart contact lenses for cancer diagnostics and screening
Scientists from the Terasaki Institute for Biomedical Innovation (TIBI) have developed a contact lens that can capture and detect exosomes, nanometer-sized vesicles found in bodily secretions which have the potential for being diagnostic cancer [...]
Novel Nanoplatform Found Effective Against Esophageal Cancer
Among the total number of deaths caused by different types of cancer, esophageal cancer is the sixth most significant. Several conventional treatments, such as radiotherapy, chemotherapy, and surgery have multiple side effects, including off-target [...]
Stem Cell Membrane-Coated Nanoparticles in Tumor Therapy
Cell membrane-coated nanoparticles, applied in targeted drug delivery strategies, combine the intrinsic advantages of synthetic nanoparticles and cell membranes. Although stem cell-based delivery systems were highlighted for their targeting capability in tumor therapy, inappropriate [...]
The TB Vaccine Mysteriously Protects Against Lots of Things. Now We Know Why
When babies in the African countries of Guinea Bissau and Uganda were given the tuberculosis vaccine, something remarkable happened. Instead of the vaccine only protecting against the target bacteria – Myocbacterium tuberculosis – the tuberculosis vaccine offered broad protection against a [...]
Extinct Pathogens Ushered The Fall of Ancient Civilizations, Scientists Say
Thousands of years ago, across the Eastern Mediterranean, multiple Bronze Age civilizations took a distinct turn for the worse at around the same time. The Old Kingdom of Egypt and the Akkadian Empire both collapsed, and there was [...]
The Origins of Covid-19 Are More Complicated Than Once Thought
IN OCTOBER 2014, virologist Edward Holmes took a tour of the Huanan Seafood Wholesale Market in Wuhan, a once relatively overlooked city of about 11 million people in the central Chinese province of Hubei. The market would [...]
Self-Healable, Human-Like Artificial Skin
Self-healable ionic sensing materials with fatigue resistance are imperative in robotics and soft electronics for extended service life. The existing artificial ionic skins with self-healing capacity were prepared by network reconfiguration, constituting low-energy amorphous [...]
Nanoparticles increase light scattering, boost solar cell performance
As demand for solar energy rises around the world, scientists are working to improve the performance of solar devices—important if the technology is to compete with traditional fuels. But researchers face theoretical limits on [...]
Scientists Use Shrimp Shell Nanoparticles to Strengthen Cement
When shrimp shell nanoparticles were mixed into cement paste, the material became substantially stronger — researchers propose an innovation that could lead to less seafood waste and fewer carbon dioxide emissions from concrete production. [...]
Does This Video Show A Nanobot Inseminating Egg With “Lazy” Sperm?
A black-and-white video shared on social media showed a microscopic corkscrew-shaped helix as it appeared to consume a sperm, transport it, and ultimately lead the little swimmer into the wall of an [...]
Study Could Help Reduce Environmental Risk of Quantum Dots
Polymers containing quantum dots (QDs) are considered crucial components of next-generation consumer items, but ambiguity remains regarding how these compounds may negatively affect public health and the environment. A pre-proof paper from the Journal of Hazardous [...]
