The development of materials toward ppb-level nitric oxide (NO) sensing at room temperature remains in high demand for the monitoring of respiratory inflammatory diseases. In order to find an iron-containing molecule without steric hindrance to combine with graphene for room temperature NO gas sensing, here a supramolecular assembly of ferrocene (Fc) and reduced graphene oxide (rGO) was designed and prepared for NO sensing. The assembly of Fc/rGO was characterized using FT-IR, TEM, and XPS measurements. The Fc/rGO-based sensors exhibited superior NO sensing properties at room temperature including high response (R_a/R_g = 1.73, 1 ppm), high selectivity against other exhaled gases, reliable repeatability and stability (less than 4 % decrease after 40 days). A practical limit of detection (LOD) of 200 ppb was achieved. The theoretical simulation demonstrates that ferrocene is assembled via π-π interaction with rGO in edge-to-face configuration which provides relatively lower energy than face-to-face configuration does for the whole assembly. It was first verified that the enhanced adsorption capacity and the charge transfer between NO and Fc/rGO would result in improvement of the assembly's sensitivity toward NO after ferrocene was assembled with graphene. This work provides a fresh approach of anchoring iron on graphene for gas sensing via supramolecular methods.

The Electronics Editorial Office retracts the article “Effects of Current Filaments on IGBT Avalanche Robustness: A Simulation Study” [1], cited above. Following publication, the authors contacted the Editorial Office regarding errors identified in the simulation model and analysis presented in the article [1]. Adhering to our standard procedure, an investigation was conducted by the Editorial Board that confirmed that the simulation presented in this paper is incorrect due to the use of incorrect material parameters: Silicon Carbide (SiC) parameters were used, instead of Silicon (Si). Consequently, the conclusions drawn from this simulation are invalid and cannot be relied upon. As a result, the Editorial Office, Editorial Board, and the authors have concluded that this error undermines the validity and accuracy of the findings, and have decided to retract this article [1] as per MDPI’s retraction policy (https://www.mdpi.com/ethics#_bookmark30). This retraction was approved by the Editor-in-Chief of the journal Electronics. The authors agree to this retraction.

Oxygen vacancy concentration in metal oxides is crucial to gas sensing performance. This study introduces a novel strategy of oxygen vacancies modulation on CoFe2O4, by two-step controllable incorporation of TiO2@MXene and carbon. In the first step, MXene simultaneously acts as an incorporation agent and a titanium source to grow TiO2 and regulate the oxygen vacancy concentration in CoFe2O4. The fabricated n-n heterojunctions of TiO2/CoFe2O4 further induced a gradient distribution of oxygen vacancies through energy band bending. And a second step, combining glucose as a carbon source, further increases the oxygen vacancy concentration in CoFe2O4 by chemical reduction during a hydrothermal process, leading to the formation of a CoFe2O4-TiO2@MXene-C nanostructured composite. Through controlling the glucose content, the ratio of Co3+ to Co2+ within the composite can be sequentially adjusted, which allows for the further regulation of oxygen vacancy concentration on the composite surface. The effectiveness of this two-step incorporation is demonstrated through enhanced acetone sensing performance, providing valuable insights into the fabrication of high-performance metal oxide-based gas sensors via controlled oxygen vacancy modulation.

Measuring respiratory rates for different age groups during monitoring and patient treatment at the hospital is extremely important. Monitoring respiratory rate for a long time provides physicians and nurses valuable information about the patient's health condition. Incorrect respiratory rate information of adults or infants can result in incorrect diagnosing and treatment of the patient. The traditional respiratory rate measurement and monitoring is contact based. However, these are quite obtrusive since the patient needs to be connected to the monitoring apparatus with wires. These methods could cause damage to vulnerable skin like preterm infants and create stress or pain. This paper introduces a novel thermographic Bio-Remote sensing approach that enables real-time face detection and respiratory rate measurement of subjects using a single thermal camera system. The algorithm achieves this without requiring nostril location, instead utilising thermal images and minimum temperature profiles for accurate detections and measurement. Furthermore, this paper discusses the significance of combining Deep Learning (DL) with the Thermal Imaging technique to provide a safer, faster, and more practical solution for hospitals by accurately measuring the respiratory rate compared to a monitoring device as the golden standard.

Nitric oxide is an endogenous biological signaling molecule, and the corresponding fractional exhaled NO serves as an important indicator in clinical diagnostics and therapeutic applications. However, achieving accurate and rapid monitoring of ppb-level fractional exhaled nitric oxide (FeNO) at room temperature remains a significant challenge. Herein, ultrathin porphyrin metal–organic framework (MOF) sheets are selected to assemble with supramolecularly functionalized graphene sheets through hydrogen bonding and electrostatic interaction with 6 nm thickness. The resulting porphyrin MOF/graphene sheet-on-sheet nanohybrid is designed as a chemiresistive NO sensor which exhibits superior gas sensing performance at room temperature including an ultralow practical limit of detection (Ra/Rg = 1.047, 5 ppb NO), reliable repeatability, excellent selectivity against other exhaled gases, and relative long-term stability. Mechanism study indicates that the prominent NO sensing performance is attributed to the ordered framework of active sites of ferric-pyrrole (Fe─N4) sites and less than 10 nm thick sheet-on-sheet heterojunction structure in the nanohybrid. The potential clinical utility of the obtained sensors is validated by exhalation tests toward exhalation samples from healthy individuals and asthma patients, respectively. This work provides an effective strategy of developing MOF-based room temperature ppb-level chemiresistive NO sensors for practical FeNO monitoring.

Achieving high-performance, low-power gas detection at room temperature is critical to safety and energy efficiency, and the key is to deeply explore the interaction mechanisms between sensitive materials and gases. In this work, a magnetic field-assisted strategy is developed to achieve high-performance, low-power NO₂ sensing with the Fe₃GaTe₂ at room temperature. Fe₃GaTe₂ nanoflakes are obtained from green solvents using ultrasound-assisted liquid phase exfoliation. The experimental results confirming that the Fe₃GaTe₂ nanoflakes sensor demonstrates an excellent response (S = 16 for 10 ppm NO₂, 1.4 times higher than that without magnetic field), a lower actual detection limit (50 ppb) and a low-power consumption (0.25 nW) under 21 mT magnetic field at room temperature. Combining theoretical calculations and quasi in situ XPS, it is indicated that Fe is the main electron donor and serves as the main response site for NO₂. Magnetic field-enhancing effect for gas sensing is revealed via comparing the in situ field-dependent magnetization curves of Fe₃GaTe₂ in air and NO₂. It is found for the first time that the enhancement of gas sensing is mainly attributed to the gas adsorption magnetic variation effect (GAMVE) which generates in NO₂. This study provides a strategy of GAMVE-driven sensing for next-generation gas sensors.

This study introduces a novel strategy for fabricating flexible nitrogen dioxide (NO₂) gas sensors based on Indium Oxide (In₂O₃) nanoparticles (NPs) employing selective reduction laser sintering (SRLS) technology. The SRSL technology utilizes ultraviolet (UV) laser selective reduction sintering to precisely and rapidly create oxygen vacancy (OV) defects in In₂O₃ NPs. These oxygen vacancies (OVs) enhance the active adsorption sites and contribute additional free electrons, significantly improving sensor performance at room temperature. The sensors demonstrate excellent response (S = 460.9 at 10 ppm), rapid response/recovery times (τ_resp/τ_reco = 27/570 s), and superior selectivity (response ratio > 400), in addition to robust resistance to light and humidity (under ppm-level NO₂ gas). The sensors also exhibit a low detection limit (200 ppb), a high signal-to-noise ratio (94.8 dB), and good long-term stability (25 days). Moreover, under photo-assisted conditions, the recovery speed of the sensors is further improved. This technology not only provides an innovative strategy for the development of high-performance flexible NO₂ gas sensors but also broadens the application potential of laser direct writing (LDW) technology in advanced materials and sensor fabrications.

For the practical diagnosis of inflammatory respiratory diseases, achieving sensitive and rapid NO sensing at the parts per billion level, all at room temperature, is of great significance. Herein, we developed a chemiresistor gas sensor with a sheet-on-sheet structure composed of an amorphous Cu-hemin MOF with reduced graphene oxide (rGO) nanosheets. The SEM images show that the Cu-hemin MOF/rGO composite exhibits a two-dimensional sheet-like structure. Due to its nanosized architecture, the Cu-hemin MOF exhibits a significant number of active sites for efficient NO detection. The Cu-hemin MOF/rGO composite material exhibited excellent NO sensing performance, including high sensitivity (Ra/Rg = 1.06, 50 ppb), reliable repeatability, high selectivity, and fast response/recovery (43 s/367 s, 10 ppm). The mechanism study revealed that the formation of the MOF altered the hemin dimer’s structure, resulting in the release of additional Fe(III)–N4 active sites and improved sensitivity. Moreover, the incorporation of rGO significantly boosted the conductivity of Cu-hemin MOFs. Using this two-dimensional sheet-like material, a mask-type sensor was also prepared and verified to be effective as a flexible and wearable sensing device for parts per billion level exhaled NO detection.

The significant in situ multicolored patterning without changing printing tools nor substrate media still remains challenging, especially toward practical applications for anti-counterfeiting. This research invented a unique universal approach for the laser-induced in situ synthesis of colorful fluorescent patterns (from blue: CIE 0.15, 0.18 to red orange: CIE 0.36, 0.39) through the controlled formation of N, S doped carbon dots (CDs) in solid composite polymer films or hydrogel with a hierarchical and physically unclonable microsurface architecture for anti-counterfeiting. The in situ patterning approach, coupled with multi-layer technique, yielding designable blue, yellow, orange, and red orange color under 365 nm in the same pattern. A 5 cm² colorful pattern can be efficiently finished within 5 min without changing the substrate and the line width accuracy can be up to 300 μm. The absolute quantum efficiency of the blue pattern reached as high as 23%. The fluorescent patterns can be survived at indoor for 24 months. The hydrogen bonding interactions between the CDs precursor and polymer facilitated the generation, uniform dispersion and stabilization of CDs during the laser irradiation. The hypothesis that laser irradiation induced photochemical reactions of CD precursors within a polymer matrix was supported by thermodynamic assessments. The universality of in situ fluorescent patterning strategy was demonstrated by developing fluorescent patterns on both solid polymer films, hydrogel, pharmaceutical packaging and textile.

Real-time pH and oxygen concentration sensing is critical for monitoring tissue damage and organ health; however, there is no report to date in such context of a single device that can simultaneously detect both pH and oxygen changes. This paper presents the development of a single optical sensor device that can simultaneously and reversibly respond to changes in both pH and oxygen concentration. The proposed optical sensor integrates both pH- and oxygen-sensitive probes, and is optimized to achieve minimal cross-sensitivity during simultaneous measurements. This approach enables high accuracy in early detection of chemical correlates of tissue or organ damage, improving screening and efficacy in organ transplants.

Purpose (stating the main purposes and research question): Anthropogenic resource use contributes to pollution, violent conflict over scarce resources, loss of biodiversity, and diminished quality of life for humans. Moreover, the “safe” amount of carbon dioxide—350 parts per million—has been exceeded. The health care industry is responsible for 4–5% of total world emissions,[i] which is similar to the global food sector.[ii] Health care carbon emissions come from health care infrastructures, supply chains and health care delivery. Increasingly, health care delivery is reliant on technologies which require the use of artificial intelligence to provide supportive care, such as triage algorithms, electronic patient records, and robotics.[iii] While these technological innovations have advanced health care significantly, they also contribute to the negative effects on the environment, among others, through carbon emissions. The environmental impacts of artificial intelligence (AI) in health care—in particular—are understudied. This research seeks to fill this gap. Methods: Our team ran an exploratory search in Scopus and PubMed to identify studies that integrate environmental sustainability, artificial intelligence, and health. Results: Our research initially yielded 735 studies. 77 of these studies focused on an environmental concern of a health technology or AI-application in a health care setting, but most of the articles in this subset addressed lowering energy consumption of a specific technology, such as a sensor or monitoring technology. Conclusions: While there have been studies looking at AI in health care; sustainability in AI; and sustainability in health care, little attention has been paid to the interface between all three. [i] Karliner, J., Slotterback, S., Boyd, R., Ashby, B., & Steele, K. 2019. Health Care’s Climate Footprint: How the Health Sector Contributes to the Global Climate Crisis and Opportunities for Action Healthcare Without HarmARUP; September. [ii] Pichler, P. P., Jaccard, I. S., Weisz, U., & Weisz, H. 2019 International Comparison of Health Care Carbon Footprints, Environmental Research Letters 14, no. 6: 064004. [iii] Khaliq, Abdul, Ali Waqas, Qasim Ali Nisar, Shahbaz Haider, and Zunaina Asghar. 2022. Application of AI and robotics in hospitality sector: A resource gain and resource loss perspective. Technology in Society 68: 101807.

This research introduces a novel and convenient technology, chitosan oligosaccharide laser lithography (COSLL), enabling the creation of flexible laser-induced graphene (LIG) on-chip microsupercapacitors (MSCs) using environmentally friendly chitosan-class polymers for the first time. MSCs prepared through COSLL exhibit a significant areal capacitance exceeding 4 mF cm^-2, comparable to that of the polyimide-LIG-based counterparts. COSLL seamlessly integrates with the micro-nano thin-film process, allowing the capacitance of resulting LIG/Au MSCs to be further increased to about 8 mF cm^-2. Leveraging an eco-friendly biomass carbon source and featuring a convenient process flowchart, COSLL emerges as an appealing method for fabricating flexible LIG on-chip MSCs.

A new type of carbonized polymer dot was prepared by the one-step hydrothermal method of triethoxylsilane (TEOS) and citric acid (CA). The sensor made from carbonized polymer dots (CPDs) showed superior gas sensing performance toward ammonia at room temperature. The Si, O-codoped CPDs exhibited superior ammonia sensing performance at room temperature, including a low practical limit of detection (pLOD) of 1 ppm (Ra/Rg: 1.10, 1 ppm), short response/recovery time (30/36 s, 1 ppm), high humidity resistance (less than 5% undulation when changing relative humidity to 80 from 30%), high stability (less than 5% initial response undulation after 120 days), reliable repeatability, and high selectivity against other interferential gases. The gas sensing mechanism was investigated through control experiments and in situ FTIR, indicating that Si, O-codoping essentially improves the electron transfer capability of CPDs and synergistically dominates the superior ammonia sensing properties of the CPDs. This work presents a facile strategy for constructing novel high-performance, single-component carbonized polymer dots for gas sensing.

Fractional exhaled nitric oxide (FeNO) can be used to describe inflammatory processes in the respiratory tract. Directly detecting ppb-level nitric oxide (NO) with chemiresistive sensors at room temperature faces the challenges of simultaneously obtaining high sensitivity and high stability for sensors. We aimed to improve the stability and sensitivity of NO sensors. We assembled sheet-like porphyrin-based MOF DLS-2D-Co-TCPP(Fe) with 5-aminonaphthalene-1-sulfonic acid-rGO (ANS-rGO) nanosheets through coordination interactions. In this way, we offered a room-temperature NO-sensing hybrid, DLS-2D-Co-TCPP(Fe)/ANS-rGO, with a sheet-on-sheet (SOS) architectural heterojunction. The DLS-2D-Co-TCPP(Fe)/ANS-rGO-based sensor demonstrated superior NO-sensing performance, including high sensitivity (R_a/R_g = 1.33, 250 ppb), reliable repeatability, high selectivity, and fast response/recovery (150 s/185 s, 1 ppm) at a sensing concentration from 100 ppb to 10 ppm at room temperature. The obtained sensor showed high stability, retaining >85% of its initial response after 60 days. Designing NO-responsive Fe-N₄ active units containing MOF nanosheets, along with constructing a heterojunction with an SOS architecture to facilitate carrier migration, collaboratively dominated the superior performance of synthesized NO sensors. This work provides a strategy for designing SOS architectural heterojunctions to obtain high-performance MOF-based gas-sensing materials.

This study introduces an innovative approach for fabricating flexible nitrogen dioxide (NO₂) gas sensors based on In2O3 nanoparticles (NPs) using selective reduction laser sintering (SRLS) technology. The SRLS technology enables specific chemical reduction reactions during the sintering process, achieving fabrication and control of oxygen vacancy defects and the porous structure in the In₂O₃ sintering region. The sensor exhibits exceptionally high sensitivity, fast response/recovery times, and superior selectivity for NO₂ gas detection, particularly at room temperature. Compared with traditional NO₂ gas sensor fabrication methods, this technology not only provides a potential way to fabricate highperformance NO₂ gas sensors but also further expands the application potential of laser direct writing (LDW) technology in the fields of advanced materials and sensor fabrication.

This study introduces a high-performance flexible temperature sensor prepared using laser-induced graphene (LIG) doped with nickel oxide (NiO) nanoparticles (NPs). Unlike conventional LIG surface doping methods, we developed a nickel oxide-doped LIG flexible temperature sensor by introducing NiO NPs into a polyimide (PI) precursor solution cured into a film followed by ultraviolet (UV) laser treatment. This approach achieves a more stable and uniform doping process while further improving the sensing performance of LIG-based temperature sensors. Over a prospective temperature detection range (30-100 °C), the sensitivity of the NiO-doped LIG temperature sensor is significantly improved from -0.064% °C-¹ to -0.079% °C-¹, an improvement of 19.3%, compared to that of the intrinsic LIG temperature sensor, while maintaining high linearity (R2 = 0.999) as well as excellent temperature stability and reliability. This research not only enhances the performance of flexible temperature sensors based on LIG but also paves new pathways for its industrial production in various application fields.

This study presents an AlN based Lamb wave (A0 mode) liquid sensing device that can be used for biomedical applications. The Lamb wave device features a 1.5 μm composite membrane consisting of a 500 nm LPCVD SiN and a 1 μm of a c-axis oriented AlN film. A 45° rotated design was also considered for this project to reduce the reflections from the edges towards the output IDT. A liquid testing experiment involving IPA, DI water, and D-PBS was performed to see if the devices were able to differentiate between these liquids. The results showed that the fabricated Lamb wave devices exhibited sensitivity to mass loading and were able to distinguish between the liquids based on their phase, frequency, and gain characteristics. Notably, devices with the rotated design have shown a substantial increase in resonance by 15 dB, as well as enhanced sensitivity, when compared to the devices with the normal design. Furthermore, the devices featuring the normal design had a Q factor of 450, whereas devices with the rotated design exhibited a Q factor of 680, indicating superior performance of the latter. These findings suggest that a Lamb wave device with the 45° rotated IDT design holds considerable potential for liquid sensing, particularly in biomedical applications.

In recent years, flexible strain sensors based on metal cracks have garnered significant interest for their exceptional sensitivity. However, striking a balance between sensitivity and detection range remains a significant challenge, which often limits its wider application. Herein, we introduce an innovative laser transmission pyrolysis technology to fabricate high-performance flexible strain sensors based on (Au) metal cracks with a microchannel array on the PDMS surface. The fabricated flexible strain sensors exhibit high sensitivity, wide detection range, precise strain resolution, fast response and recovery times, and robust durability. Furthermore, this technology has potential applications in microfluidics, microelectromechanical systems, and optical sensing.

In this study, a convenient chitosan oligosaccharide laser lithograph (COSLL) technology was developed to fabricate laser-induced graphene (LIG) electrodes and flexible on-chip microsupercapacitors (MSCs). With a simple one-step CO₂ laser, the pyrolysis of a chitosan oligosaccharide (COS) and in situ welding of the generated LIGs to engineering plastic substrates are achieved simultaneously. The resulting LIG products display a hierarchical porous architecture, excellent electrical conductivity (6.3 Ω sq^-1), and superhydrophilic properties, making them ideal electrode materials for MSCs. The pyrolysis-welding coupled mechanism is deeply discussed through cross-sectional analyses and finite element simulations. The MSCs prepared by COSLL exhibit considerable areal capacitance of over 4 mF cm^-2, which is comparable to that of the polyimide-LIG-based counterpart. COSLL is also compatible with complementary metal-oxide-semiconductor (CMOS) and micro-electro-mechanical system (MEMS) processes, enabling the fabrication of LIG/Au MSCs with comparable areal capacitance and lower internal resistance. Furthermore, the as-prepared MSCs demonstrate excellent mechanical robustness, long-cycle capability, and ease of series-parallel integration, benefiting their practical application in various scenarios. With the use of eco-friendly biomass carbon source and convenient process flowchart, the COSLL emerges as an attractive method for the fabrication of flexible LIG on-chip MSCs and various other advanced LIG devices.

Inspired by the activation mechanism of slow anion channels 1 (SLAC1) in plants that proton pump reversibly induces plant stomata open for CO2 adsorption, a CO2-switching H+ conduction/HCO3− diffusion dual ion channel (CO2-switching-DIC) was constructed by assembling γ-cyclodextrin-MOF (γ-CD-MOF) and 3,4,9,10-perylenetetracarboxylic acid (PTCA) for CO2 chemiresistive sensing. The obtained CO2 sensor exhibited high response (Rg/R0 = 1.33, 50 ppm) and selectivity, low practical limit of detection (1 ppm) and excellent consistency (94.5%) with a commercial infrared CO2 meter at room temperature. It is indicated that hydrogen bond networks in CO2-switching-DIC will be enlarged with the increasing of carboxylic group’s content on perylene skeleton, thereby modulating proton conductivity at molecular level and furthermore CO2 sensing performance of the composite. The CO2-switching-DIC-based sensor has been utilized to distinguish the exhaled CO2 concentration between lung cancer patients and healthy individuals, illustrating its promising application prospect in non-invasive diagnose.