Advanced Sensor Research最新文献

Palladium nanoparticle (Pd NP)-based resistive-type hydrogen (H₂) sensors are susceptible to interference from oxygen when detecting H₂. In contrast, capacitive-type sensors emerge as promising candidates for addressing this issue, owing to their unique operating principle. Herein, a capacitive-type H₂ sensor is developed to verify the conception, using Pd NPs as the sensing material and integrating them into a novel 3D interdigital electrode (IDE) structure fabricated on a silicon wafer via microelectromechanical systems (MEMS) technology. Comprehensive characterization of the Pd NPs within the 3D IDEs reveals a strong correlation between sensitivity and Pd NP content, with peak sensitivity (61.94) attained at 20 000 ppm H₂ for ≈0.7 mg of Pd NPs. The sensor demonstrated negligible interference from CH₄, CO₂, and CO, underscoring its exceptional selectivity for H₂. Particularly, variation of oxygen concentration in the background gas shows a minor impact on the sensing performance of the developed capacitive H₂ sensor. Additionally, density functional theory (DFT) calculations provide insight into the volumetric expansion of Pd at different H/Pd ratios, showing a maximum expansion of 13.7% at an H/Pd ratio of 1. This work highlights the potential of capacitive-type sensors for high-performance tracking H₂, paving the way for advanced applications in H₂ monitoring.

Analysing the exhaled breath and its condensate (EBC) can offer a simple, non-invasive way to track physiological states through volatile and non-volatile biomarkers detection. Biosensors, leveraging biological recognition elements, as enzymes, promise selective recognition of these analytes and can overcome the limitations of traditional gas sensors. However, transitioning from liquid to gas-phase sensing presents significant challenges, including enzyme instability, weak signals, and lack of sampling standardization. On the other hand, EBC biosensors, while more compatible with biological elements, face limitations due to the low analyte concentrations and variable sample quality. This perspective looks at the current progress in gas-phase and EBC-based biosensors, highlighting the most promising emerging technologies and key limitations. With the right advances, these tools can facilitate the implementation of fast and non-invasive testing in routine healthcare.

Various animals in nature, particularly insects, are equipped with sensory hair capable of detecting minute fluid forces. Inspired by these biological structures, numerous airflow sensors have been developed using Si-based microelectromechanical systems. However, the complexity of the fabrication process and difficulty in integrating shape-controlled sensing elements remain significant challenges. Laser-induced graphene (LIG) has attracted increasing attention as a promising material for various physical sensors, owing to its high piezoresistive sensitivity and simple fabrication process. Polyimide (PI), which is widely used as a substrate for LIG formation, exhibits thermoplastic properties that enable the straightforward creation of 3D structures. This study proposes a single-axis airflow sensor featuring a vertically standing LIG cantilever. The fabrication process involved only a fiber laser for cutting the PI film, forming the LIG-sensing elements, and folding the cantilever structure. The fabricated sensor measured 25 mm × 25 mm at the base and 10.5 mm high. The fabricated sensor integrated surface-mounted circuits within its base. Wind tunnel experiments demonstrate that the sensor exhibits a quadratic response to wind speeds between −10 and 10 m s⁻¹. This approach offers promising prospects for the development of 3D LIG sensing elements for airflow sensors.

Non-enzymatic high-performance glucose sensors are important due to their stability and low cost. Nickel oxide and its composites with various materials such as multi-walled carbon nanotubes (MWCNTs) have emerged as a platform for non-enzymatic glucose detection at micromolar concentrations. In this article, the reaction mechanism within a MWCNTs/NiO/MWCNTs stacked electrode system used for glucose detection is explored and elucidated. Micro-Raman and -Xray Photoelectron Spectroscopy are used to track the changes associated with the chemical state of the MWCNTs in the composite electrode during the oxidation of glucose molecules. The results show that the presence of MWCNTs provides abundant active sites for the electrochemical reaction. The enhanced electron transfer improves sensor sensitivity as evidenced by distinct redox peaks in the cyclic voltammograms. We conclude that the MWCNTs used herewith provide an ultrahigh surface-area-to-volume ratio for the adsorption of OH⁻ ions from the alkaline medium, which, in turn, facilitates the formation of NiOOH from NiO. The NiOOH formed further acts as an oxidizing agent for glucose molecules, altering them to gluconolactone via a chemical reaction that produces hydrogen peroxide while regenerating NiO. The detailed understanding of the reaction mechanism underscores the significant role of MWCNTs in enhancing the efficiency and sensitivity of non-enzymatic glucose sensors.

Recyclable Printed Thermocouples

In article 2400182, Rui Xu, Denys Makarov, and co-workers develop recyclable printed thermocouples featuring eco-friendly design as well as low cost and scalable processing. Magnetic flakes and re-dissolvable polymers enable seamless and efficient magnet-assisted recycling, preserving performance for sustainable large-scale manufacturing.

FKBP12, a peptidyl-prolyl isomerase implicated in cancer, neurodegenerative diseases, and post-transplant anti-rejection mechanisms, represents a critical biomarker for early diagnosis and monitoring. Here, a novel diagnostic nanoplatform is presented for the detection of FKBP12 at nanomolar to picomolar concentrations in biological fluids. The platform integrates a gold-coated Quartz Crystal Microbalance (QCM) functionalized with a synthetic receptor (GPS-SH1) and spacers within a Self-Assembled Monolayer (SAM), enabling direct and label-free detection of FKBP12 in complex biological samples. A careful strategy for the in-silico design and custom synthesis of the receptor is adopted, ensuring optimal binding affinity and additional chemical functionalities for surface chemisorption. The designed nano-architecture demonstrates exceptional sensitivity, with a detection limit in the picomolar range, and high selectivity, as confirmed by minimal interference from abundant serum proteins such as Serum Albumin and Immune Gamma Globulin. Furthermore, the SAM-functionalized sensors exhibit remarkable stability, retaining functionality for up to six months under storage conditions. This work not only advances the field of nanoscale biosensing but also provides a robust, reusable tool for FKBP12 detection, with potential applications in point-of-care diagnostics and personalized medicine. The platform's ability to operate in biologically relevant environments underscores its promise for real-world healthcare applications, including early disease diagnostics.

From 2020 to 2023, the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global health crisis, as millions of people worldwide contracted the coronavirus disease of 2019 (COVID-19). Conventional diagnostic techniques, such as reverse transcription-quantitative polymerase chain reaction (RT-PCR), struggled to meet increasing testing needs required for a pandemic owing to significant downsides hindering their large-scale use. In efforts to curb the effects of the pandemic and to meet the increasing demand for fast and accurate point-of-care (POC) testing, scientists and industries alike raced to engineer new diagnosis methods and adapt previously developed ones. Now that the COVID-19 pandemic has passed, the present review aims to provide the reader with an overview of recent advances in biosensing resulting from these efforts and to offer insight for future pandemics. This review focuses on nanomaterial-based optical biosensors, which are central to multiple emerging diagnostic tools. It covers techniques such as lateral flow immunoassays (LFIA), plasmonic biosensors based on surface plasmon resonance (SPR) and localized SPR (LSPR), surface-enhanced Raman spectroscopy (SERS), and surface-enhanced fluorescence (SEF). LFIAs played an important role in the COVID-19 pandemic and will continue to shape biosensing in future pandemics, while other techniques are yet to reach commercialization despite recent strides.

Implantable and resorbable electronic devices show excellent potential for short-term medical monitoring, especially in the context of post-surgical care. Bioresorbable sensors are of special interest, as they eliminate the need for surgical retrieval, thereby reducing patient risk and clinical burden. In this work, Polydioxanone (PDO) is explored, a medically licensed, flexible, resorbable material, as a promising substrate for the integration of bioresorbable electronic components. Using a targeted, bottom-up approach, the feasibility of integrating basic electronic elements and sensors is demonstrated directly on PDO, including resistive temperature sensors, conductivity sensors for electrolytic environments, organic electrochemical transistors, and passive antennas for potential wireless communication. This work highlights the potential of PDO as a platform material for future fully resorbable medical devices and contributes to the growing toolkit for fully resorbable sensor technologies.

Film-based fluorescence sensors are attractive for illicit drugs detection due to their potential for rapid response, low limits of detection, and portability. However, it is still a significant challenge to achieve real-time identification of suspected illicit drugs using fluorescence detection. Herein, four novel 1,8-naphthalimide (NI) derivatives with different substituents at the 4-position, namely NI-1 [phenyl], NI-2 [4-({2-ethylhexyl}oxy)phenyl], NI-3 [4,4''-bis({2-ethylhexyl}oxy)-(1,1':3',1''-terphenyl)-5'-yl] and NI-4 [4-(dimesitylboraneyl)phenyl] are reported. The four NI derivatives had different thin film optoelectronic properties and mass densities, and showed distinct fluorescence responses to methamphetamine hydrochloride, 3,4-methylenedioxyamphetamine hydrochloride, cocaine hydrochloride, fentanyl hydrochloride, and tetrahydrocannabinol. The contrasting fluorescence responses of NI-1, NI-2, NI-3 and NI-4 were utilized as the basis for a constructed sensor array, which can distinguish between five drugs, three compounds commonly found around the home (paracetamol, aspirin and caffeine) and a null class (a blank swab) in 18 s with a mean classification accuracy of 81%. By grouping analyte predictions into binary “drug” and “other” categories, a 94% mean classification accuracy is achieved. This highlights the potential for thin film fluorescent NI derivatives to be used for rapid on-site drug screening.