Enhancing the evanescent field in TiO2/Au hybrid thin films creates a highly sensitive room-temperature formaldehyde gas biosensor

Recent advances in biosensors detecting biomarkers from exhaled breath and saliva for respiratory disease diagnosis

The global demand for rapid and non-invasive diagnostic methods for respiratory diseases has significantly intensified due to the wide spread of respiratory infectious diseases. Recent advancements in respiratory disease diagnosis through the analysis of exhaled breath and saliva has attracted great attention all over the world. Among various analytical methods, biosensors can offer non-invasive, efficient, and cost-effective diagnostic capabilities, emerging as promising tools in this area. This review intends to provide a comprehensive overview of various biosensors for the detection of respiratory disease related biomarkers in exhaled breath and saliva. Firstly, the characteristics of exhaled breath and saliva, including their generation, composition, and relevant biomarkers are introduced. Subsequently, the design and application of various biosensors for detecting these biomarkers are presented, along with the innovative materials employed as sensitive components. Different types of biosensors are reviewed, including electrochemical, optical, piezoelectric, semiconductor, and other novel biosensors. At last, the challenges, limitations, and future trends of these biosensors are discussed. It is anticipated that biosensors will play a significant role in respiratory disease diagnosis in the future.

The Biomedical Applications of Biomolecule Integrated Biosensors for Cell Monitoring

Cell monitoring is essential for understanding the physiological conditions and cell abnormalities induced by various stimuli, such as stress factors, microbial invasion, and diseases. Currently, various techniques for detecting cell abnormalities and metabolites originating from specific cells are employed to obtain information on cells in terms of human health. Although the states of cells have traditionally been accessed using instrument-based analysis, this has been replaced by various sensor systems equipped with new materials and technologies. Various sensor systems have been developed for monitoring cells by recognizing biological markers such as proteins on cell surfaces, components on plasma membranes, secreted metabolites, and DNA sequences. Sensor systems are classified into subclasses, such as chemical sensors and biosensors, based on the components used to recognize the targets. In this review, we aim to outline the fundamental principles of sensor systems used for monitoring cells, encompassing both biosensors and chemical sensors. Specifically, we focus on biosensing systems in terms of the types of sensing and signal-transducing elements and introduce recent advancements and applications of biosensors. Finally, we address the present challenges in biosensor systems and the prospects that should be considered to enhance biosensor performance. Although this review covers the application of biosensors for monitoring cells, we believe that it can provide valuable insights for researchers and general readers interested in the advancements of biosensing and its further applications in biomedical fields.

Temperature Sensor Based on Surface Plasmon Resonance with TiO2-Au-TiO2 Triple Structure

Temperature sensors have been widely applied in daily life and production, but little attention has been paid to the research on temperature sensors based on surface plasmon resonance (SPR) sensors. Therefore, an SPR temperature sensor with a triple structure of titanium dioxide (TiO2) film, gold (Au) film, and TiO2 nanorods is proposed in this article. By optimizing the thickness and structure of TiO2 film and nanorods and Au film, it is found that the sensitivity of the SPR temperature sensor can achieve 6038.53 nm/RIU and the detection temperature sensitivity is -2.40 nm/°C. According to the results, the sensitivity of the optimized sensor is 77.81% higher than that of the sensor with pure Au film, which is attributed to the TiO2(film)-Au-TiO2(nanorods) structure. Moreover, there is a good linear correlation (greater than 0.99) between temperature and resonance wavelength in the range from 0 °C to 60 °C, which can ensure the detection resolution. The high sensitivity, FOM, and detection resolution indicate that the proposed SPR sensor has a promising application in temperature monitoring.

Highly Selective Gas Sensor Based on Hydrophobic Silica Decorated with Trimethoxyoctadecylsilane

Trimethoxyoctadecylsilane (OTMS) was successfully used to decorate mesoporous silica with a self-assembly method to enhance the relative gas selectivity. A quartz crystal microbalance was employed to measure the gas-sensing properties. The content of OTMS was the crucial factor that greatly affected the adsorption capacity (q) of silica, which could be converted to relative selectivity (S) to study the sensing mechanism. With increasing OTMS content, q was far higher for small-molecule gases compared to volatile organic compounds (VOCs), which could be explained by the polarity of the bonding objects, and S reached a maximum value of 45.71%. When exposed to VOCs, S was always greater than 0 among the three alcohols. The sensing mechanisms of undecorated silica and OTMS-decorated silica were quite different; the three-state mechanism was proposed to explain the sensing mechanism of OTMS-decorated silica. When exposed to small-molecule gases, the atoms that bonded with carbon atoms on OTMS greatly influenced q. With increasing OTMS content, the bonding energy of OTMS with CO₂ was far less than that with other molecules, resulting in a relative selectivity as high as 38.69%. Furthermore, macroperformance and microproperties were combined in three-dimensional coordinates, which could be applied to predict the sensing performance of silica.

High-Tech and Nature-Made Nanocomposites and Their Applications in the Field of Sensors and Biosensors for Gas Detection

Gas sensors have been object of increasing attention by the scientific community in recent years. For the development of the sensing element, two major trends seem to have appeared. On one hand, the possibility of creating complex structures at the nanoscale level has given rise to ever more sensitive sensors based on metal oxides and metal-polymer combinations. On the other hand, gas biosensors have started to be developed, thanks to their intrinsic ability to be selective for the target analyte. In this review, we analyze the recent progress in both areas and underline their strength, current problems, and future perspectives.