Ultrasensitive Chemiresistive Gas Sensor Can Diagnose Asthma and Monitor Its Severity by Analyzing Its Biomarker H₂S: An Experimental, Clinical, and Theoretical Study

Abstract

Asthma is a chronic disease characterized by recurrent attacks of breathlessness and wheezing, which vary in severity and frequency from person to person. H2S is considered as the biomarker of asthma. Here, an ultrasensitive chemiresistive H2S gas sensor based on a γ-Bi2MoO6–CuO heterostructure with a detection limit of 5 ppb has been fabricated. It can distinguish asthmatic patients from healthy people roughly by analyzing the exhaled breaths of 28 asthmatic patients and 28 healthy people, suggesting that the sensor can be used to assist physicians in the diagnosis of asthma. Pathologically, it is discovered by this sensor that with the relief of asthma, the concentration of H2S in one’s exhaled breath gradually increases. This subtle concentration variation of H2S can be accurately detected, indicating that this sensor can be used in the asthma severity monitoring too. Physical models have been built by first-principles calculation to reveal the causes of the sensor’s ultrasensitivity. The stable adsorption of H2S on the surface of CuO results in massive charge transferring and the appearance of the defect states, which play the major role in the ultrasensitivity of the sensor. Upon integrating this sensor with circuits, the cheap, smart, and portable H2S sensing device can be obtained, which can make asthmatic patients’ access to this device easy and make the severity monitoring of asthma convenient, especially for children and the aged.

Fabrication and Computational Study of a Chemiresistive NO2 Gas Sensor Based on the Carbon Dots-WO3 Heterostructure for Operating below Room Temperature

“…The presence of the CC peak indicates that the Cdots are made of a graphitic structure, whereas the C–O and CO peaks suggest that the Cdots have adsorbed oxygen on the surface. According to analyses shown in 1.0 Section in the Supporting Information, the tungsten element belongs to W 6+ of WO 3 , , and there are lattice oxygen and surface oxygen vacancy defects , on the surface of the sample.…”

Emerging Sensing and In Situ Detection Technologies for the Analysis of Extracellular Vesicle miRNAs

“…EV‐miRNAs are associated with the progression of many cancers, and several emerging assays have been validated in clinical samples, mostly from serum or plasma, but also from urine and some tissue fluids. These assays detect single or multiple miRNAs for the diagnosis of related diseases such as PDAC, [ 98 ] breast cancer, [ 99 ] CRC, [ 100 ] thyroid cancer, [ 101 ] and oral squamous cell carcinoma. [ 102 ] Emerging assays have shown good performance in the detection of EV‐miRNAs due to their high specificity and sensitivity ( Table 2 ).…”

Ultrasensitive Bio-H2S Gas Sensor Based on Cu2O-MWCNT Heterostructures

“…Hydrogen sulfide (H 2 S), a recognized gas biomarker for disease diagnosis, is the third endogenous gas medium discovered after NO and CO and acts as a messenger in many important physiological processes, including vasodilation, blood-pressure regulation, myocardial regulation, and anti-inflammatory processes. − Thus, the correlation between H 2 S abnormal metabolism and pathological changes is self-evident. Some diseases that patients need to struggle with for a long time, such as halitosis, asthma, hypertension, and Alzheimer’s disease, can cause abnormal H 2 S concentrations in exhaled gas. If the development of noninvasive H 2 S sensors that are affordable, simple to operate, and capable of real-time detection obtained a breakthrough, it would greatly reduce the pressure of hospital visits and even improve the control of the disease.…”

“…8−10 Thus, the correlation between H 2 S abnormal metabolism and pathological changes is self-evident. Some diseases that patients need to struggle with for a long time, such as halitosis, 11 asthma, 12 hypertension, 13 and Alzheimer's disease, 14 can cause abnormal H 2 S concentrations in exhaled gas. If the development of noninvasive H 2 S sensors that are affordable, simple to operate, and capable of real-time detection obtained a breakthrough, it would greatly reduce the pressure of hospital visits and even improve the control of the disease.…”