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
Platelet-inspired nanoparticles could improve treatment of inflammatory diseases
Scientists have developed platelet-inspired nanoparticles that deliver anti-inflammatory drugs directly to brain-computer interface implants, doubling their effectiveness. Scientists have found a way to improve the performance of brain-computer interface (BCI) electrodes by delivering anti-inflammatory drugs directly [...]
After 150 years, a new chapter in cancer therapy is finally beginning
For decades, researchers have been looking for ways to destroy cancer cells in a targeted manner without further weakening the body. But for many patients whose immune system is severely impaired by chemotherapy or radiation, [...]
Older chemical libraries show promise for fighting resistant strains of COVID-19 virus
SARS‑CoV‑2, the virus that causes COVID-19, continues to mutate, with some newer strains becoming less responsive to current antiviral treatments like Paxlovid. Now, University of California San Diego scientists and an international team of [...]
Lower doses of immunotherapy for skin cancer give better results, study suggests
According to a new study, lower doses of approved immunotherapy for malignant melanoma can give better results against tumors, while reducing side effects. This is reported by researchers at Karolinska Institutet in the Journal of the National [...]
Researchers highlight five pathways through which microplastics can harm the brain
Microplastics could be fueling neurodegenerative diseases like Alzheimer's and Parkinson's, with a new study highlighting five ways microplastics can trigger inflammation and damage in the brain. More than 57 million people live with dementia, [...]
Tiny Metal Nanodots Obliterate Cancer Cells While Largely Sparing Healthy Tissue
Scientists have developed tiny metal-oxide particles that push cancer cells past their stress limits while sparing healthy tissue. An international team led by RMIT University has developed tiny particles called nanodots, crafted from a metallic compound, [...]
Gold Nanoclusters Could Supercharge Quantum Computers
Researchers found that gold “super atoms” can behave like the atoms in top-tier quantum systems—only far easier to scale. These tiny clusters can be customized at the molecular level, offering a powerful, tunable foundation [...]
A single shot of HPV vaccine may be enough to fight cervical cancer, study finds
WASHINGTON -- A single HPV vaccination appears just as effective as two doses at preventing the viral infection that causes cervical cancer, researchers reported Wednesday. HPV, or human papillomavirus, is very common and spread [...]
New technique overcomes technological barrier in 3D brain imaging
Scientists at the Swiss Light Source SLS have succeeded in mapping a piece of brain tissue in 3D at unprecedented resolution using X-rays, non-destructively. The breakthrough overcomes a long-standing technological barrier that had limited [...]
Scientists Uncover Hidden Blood Pattern in Long COVID
Researchers found persistent microclot and NET structures in Long COVID blood that may explain long-lasting symptoms. Researchers examining Long COVID have identified a structural connection between circulating microclots and neutrophil extracellular traps (NETs). The [...]
This Cellular Trick Helps Cancer Spread, but Could Also Stop It
Groups of normal cbiells can sense far into their surroundings, helping explain cancer cell migration. Understanding this ability could lead to new ways to limit tumor spread. The tale of the princess and the [...]
New mRNA therapy targets drug-resistant pneumonia
Bacteria that multiply on surfaces are a major headache in health care when they gain a foothold on, for example, implants or in catheters. Researchers at Chalmers University of Technology in Sweden have found [...]
Current Heart Health Guidelines Are Failing To Catch a Deadly Genetic Killer
New research reveals that standard screening misses most people with a common inherited cholesterol disorder. A Mayo Clinic study reports that current genetic screening guidelines overlook most people who have familial hypercholesterolemia, an inherited disorder that [...]
Scientists Identify the Evolutionary “Purpose” of Consciousness
Summary: Researchers at Ruhr University Bochum explore why consciousness evolved and why different species developed it in distinct ways. By comparing humans with birds, they show that complex awareness may arise through different neural architectures yet [...]
Novel mRNA therapy curbs antibiotic-resistant infections in preclinical lung models
Researchers at the Icahn School of Medicine at Mount Sinai and collaborators have reported early success with a novel mRNA-based therapy designed to combat antibiotic-resistant bacteria. The findings, published in Nature Biotechnology, show that in [...]
New skin-permeable polymer delivers insulin without needles
A breakthrough zwitterionic polymer slips through the skin’s toughest barriers, carrying insulin deep into tissue and normalizing blood sugar, offering patients a painless alternative to daily injections. A recent study published in the journal Nature examines [...]
