Advanced Sensor Research最新文献

This study investigates how the emission mechanism (fluorescence, phosphorescence, or thermally activated delayed fluorescence, TADF) of a luminescence-quenching chemical sensor influences the sensitivity of explosives detection. Steady-state and time-resolved photoluminescence measurements were used to evaluate the quenching kinetics of representative emitters in the presence of 2,4-dinitrotoluene (DNT), a model nitroaromatic explosive. Linear Stern-Volmer behavior was observed for the fluorescent and phosphorescent emitters, whereas the TADF compound exhibited a pronounced downward deviation in steady-state measurements, arising from the simultaneous but distinct quenching of singlet and triplet exciton populations. To describe this behavior, we derived a modified Stern–Volmer formalism comprising separate relationships for the prompt and delayed fluorescence. The quenching dynamics of the TADF system were found to be strongly dependent on the intrinsic parameters $$, k_Stot and k_Ttot, with the singlet and triplet populations being quenched with different efficiencies. These insights highlight the potential of TADF luminophores to act as sensitive photoinduced electron transfer-based explosives sensors.

A high-performance capacitive sensor is presented for the determination of hydroquinone (HQ) based on n-type indium phosphide (n-InP) electrodes with an electrochemically deposited polyphosphazene (PPP) coating. The integration of PPP with InP electrodes offers a previously unexplored approach to chemical sensing. The polymer film is deposited evenly and well examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS), which confirms the formation of a chemically stable and passivating interface. Capacitance–voltage (C–V) measurements in phosphate-buffered saline (PBS) reveal a linear detection range of 1–100 µm and a limit of detection (LOD) of 0.73 µm (n = 3), highlighting the sensitivity of the sensor. Selectivity tests indicate minimal interferences from structurally related phenolic substances such as catechol and phenol, corroborating the very high selectivity toward HQ. This capacitive sensing platform offers a promising approach for the rapid, sensitive, and selective detection of these hazardous chemicals, with vast potential for use in environmental monitoring and analytical fields.

Research in the domain of wearable electronics is observing a paradigm shift. Nowadays, most researchers are focusing on developing a unique wearable sensor solution for the early prognosis of several life-threatening diseases. Not only is prognosis important, but gaining a deeper insight into the underlying causality with the aid of sensors is also becoming popular. Among the various diseases, challenges related to respiratory disorders are potentially increasing worldwide. Accordingly, a lot of research is now being conducted to appropriately understand the various facets using such sensors. Therefore, in this review, the potential of polymer nanocomposite-based respiratory sensors has been examined. Representative examples of developing such sensors are discussed. The various mechanistic approaches that control the detection mechanism in such sensors are explored. Further, this review also discusses important factors such as cross-interference of signals and their impact on the final results. The futuristic self-powered respiratory sensors, with emphasis on triboelectric nanogenerators (TENG) and moisture electric generators (MEG), are discussed. All the sections are supported through examples from the literature. As a future outlook, the potential contributions of artificial intelligence (AI) and material improvisation to the growth and development of this field have also been discussed.

Non-Enzymatic Electrochemical Glucose Sensor

In the Research Article (DOI: 10.1002/adsr.202500069), Rahul Panat, Suhas Jejurikar, and co-workers demonstrate effective detection of glucose molecules using a carbon paper electrode modified by a stack of MWCNTs and NiO. Various characterization techniques show that the unique combination of materials in the stack enhances the electrocatalytic activity of the electrode, leading to the observed effects. This approach leads to enhanced non-enzymatic sensors for biomolecule detection.

Achieving and maintaining optimal oral health necessitates a comprehensive understanding of the complex bio-adhesive and metabolic processes occurring within the oral cavity. These processes are significantly influenced by the intricate composition of oral fluids, particularly saliva and its resident microbiome. Currently available methodologies struggle to accurately monitor the dynamic and heterogeneous nature of key oral biomarkers, such as glucose. The development of miniaturized sensors for continuous and quantitative monitoring of clinically relevant salivary parameters represents a significant advancement in diagnostic capabilities. This work introduces an electrochemical sensor array designed for the continuous, quantitative monitoring of the clinically relevant and paradigmatic metabolite glucose. To address the challenges posed by the complex salivary environment, a surface modification strategy is implemented involving hybrid films of Prussian blue with chitosan and glucose oxidase enzyme entrapped within chitosan. The incorporation of chitosan, along with the further integration of zwitterionic polymer based on self-polymerized dopamine (pDA) and 2- Methacryloyloxyethyl Phosphoryl Choline (MPC), facilitates the sensitive, selective, and reliable glucose monitoring in harsh salivary environments. Continuous amperometric glucose monitoring showcases the platform's capability for real-time quantification, as increasing glucose concentrations correspond with elevated current signals. Pilot experiments show the sensors' capacity to precisely quantify salivary glucose levels and ascertain unknown concentrations, validated through the use of commercial glucometers. While the initial focus lies on glucose detection as a proof of concept, the final device integrates multiple electrochemical and potentiometric sensors. This advanced configuration enables the comprehensive quantification of several clinically relevant parameters in saliva. The development of multi-sensor devices for continuous monitoring within the oral cavity holds immense potential: by unlocking deeper insights into the mechanisms driving the onset and progression of oral diseases, it will pave the way for further innovations in preventive dentistry.

Excessive sun exposure is the major environmental risk factor for melanoma and other types of skin cancer. Reducing cumulative exposure to ultraviolet (UV) radiation and avoiding repeated, sporadic episodes of acute photodamage can drastically lower this risk. Photodamage after sun exposure can be assessed by monitoring erythema – skin redness – and increased pigmentation, both key indicators of excessive UV exposure. In this work, a compact optical device designed to monitor changes in pigmentation and erythema through reflectance measurements using four micro-LEDs is presented, emitting at 405, 572, 650, and 700 nm, and a photodiode with extended visible-near infrared sensitivity. Monte Carlo simulations are conducted to optimize the device design by evaluating light penetration into skin tissue as a function of source-to-detector distance to target key chromophores. The device is validated using skin-mimicking tissue phantoms containing coffee, with similar optical properties to melanin, and hemoglobin to simulate changes in pigmentation and erythema, respectively. Using a signal-to-noise ratio threshold of 2, it is able to detect changes in pigmentation as small as 5% across all phototypes and erythema changes in lighter skin tones. This miniaturized device shows potential for personalized skin monitoring in therapeutic, cosmetic, and diagnostic applications.

In this study, a novel 3D-printed glassy carbon gyroid anode is constructed using stereolithography, aiming to improve microbial fuel cell (MFC)-based biosensor performance through a simple method that optimizes both the macroporous structure and hydrophilicity of the anode. Comparative studies are conducted between MFC-based biosensors with traditional carbon felt (CF-MFCs) and those with the 3D-printed resin anode (RE-MFCs). In batch mode, RE-MFCs show a linear dynamic range from 26 to 405 mg L⁻¹, +126% higher than CF-MFCs (26–194 mg L⁻¹). However, a reduction in sensitivity is observed (0.40 ± 0.08 mA m⁻² mg⁻¹ L⁻¹ for RE-MFCs and 1.02 ± 0.08 mA m⁻² mg⁻¹ L⁻¹). In continuous flow mode at a flow rate of 0.1 mL min⁻¹ (HRT = 5 h), the RE-MFCs demonstrated up to 35% higher sensitivity (1.45 mA m⁻² mg⁻¹ L⁻¹) than the CF-MFCs (0.94 mA m⁻² mg⁻¹ L⁻¹) due to increased mass transport and better biofilm activity. Despite using the same inoculum, different microbial electroactive biofilms formed on the CF and RE anodes. Biofilm communities are influenced more by the operation mode than by the anode material choice. This study introduces an innovative anode material that can be tailored to increase dynamic range or sensitivity based on MFC operation mode and calibration strategy.

Biosensing by Particle Motion (BPM) is an affinity-based biosensing technology for the continuous monitoring of concentrations of specific biomolecules. Previous work has shown that BPM sensor signals change over long time spans, caused in part by losses of binder molecules from the particles and the sensing surface. This paper studies whether the aging effects of particles and the sensing surface depend on the applied temperature. Particles and surface were separately aged, and their functionalities were quantified in a glycoalkaloid BPM sensor, with anti-solanidine antibodies on the particles and solanidine-analogue on the sensing surface. The results show that the particles are stable up to 40 °C and lose functionality when exposed to 50 °C and higher. The surface aging experiments show both decreasing and increasing signals with temperature exposures, potentially caused by rearrangements of the low-fouling polymer coating on the sensing surface. The experimental results give pointers on how long-term changes of continuous biosensors can be studied and eventually mitigated.

Lipid droplets (LDs) and the endoplasmic reticulum (ER) are dynamic organelles central to cellular metabolism, signaling, and stress response. Despite their biological relevance and close interplay, tools to selectively track their dynamic behavior remain limited. Here, the design, synthesis, and characterization of a new class of fluorescent probes obtained through green multicomponent synthetic strategies are reported. These previously unexplored fluorophore scaffolds display unexpected and differential subcellular localization, selectively targeting either LDs or the ER with high photostability. Mechanistic studies suggest that such selectivity arises from a synergistic interplay between partition coefficient, conformational geometry, and strategically positioned targeting moieties. These features enable the probes to adapt to distinct microenvironments within cells, supporting real-time visualization of both LD and ER dynamics. These findings provide versatile sensing tools and novel insights into organelle-targeting principles, establishing an eco-conscious route to next-generation fluorescent sensors.