Advanced Sensor Research最新文献

The excitation of microresonators using focused intensity modulated light, known as photothermal excitation, is gaining significant attention due to its capacity to accurately excite microresonators without distortions, even in liquid environments, which is driving key advancements in atomic force microscopy and related technologies. Despite progress in the development of coatings, the conversion of light into mechanical movement remains largely inefficient, limiting resonator movements to tens of nanometers even when milliwatts of optical power are used. Moreover, how photothermal efficiency depends on the relative position of a microresonator along the propagation axis of the photothermal beam remains poorly studied, hampering the understanding of the conversion of light into mechanical motion. Here, photothermal measurements are performed in air and water using cantilever microresonators and a custom-built picobalance, to determine how photothermal efficiency changes along the propagation beam axis. It is identified that far out-of-band laser emission can lead to visual misidentification of the beam waist, resulting in a drop of photothermal efficiency of up to one order of magnitude. The measurements also unveil that the beam waist is not always the position of highest photothermal efficiency, and can reduce the efficiency up to 20% for silicon cantilevers with trapezoidal cross section.

Hypochlorite (ClO⁻), an essential reactive oxygen species (ROS) in physiological processes, is identified to be closely connected with oxidative stress and related diseases. Meanwhile, ClO⁻ is a commonly-used disinfector for water treatment, and in public places, under acidic conditions, it's easily decomposed into hypertoxic chlorine gas. Since the strong oxidizing property of ClO⁻, many oxidizing agents may disturb the ClO⁻ detection. Specific and accurate detection of ClO⁻ with superior sensitivity is a challenge. In this work, a sensing platform for rapid, sensitive, and specific ClO⁻ detection is constructed using green fluorescent carbon dots (G-CDs), with a linear detection range of 0.5–11 µm and a detection limit of 0.233 µm. Moreover, introducing a red fluorescent tripyridinium ruthenium ([Ru(bpy)₃]²⁺) as a reference, a ratiometric fluorescence nanoprobe G-CDs@[Ru(bpy)₃]²⁺ is prepared and shows favorable intracellular imaging of exogenous and endogenous ClO⁻. With G-CDs@[Ru(bpy)₃]²⁺-based test paper microarrays and a color recognition APP, a smartphone-based sensing system for point-of-care testing of ClO⁻ is also fabricated. In summary, this work proposed a versatile and economical smartphone-based sensing system that featured reliability and simplicity, and suggested its potential applications in environmental water quality monitoring and live cell imaging.

Triboelectric nanogenerators (TENGs) are getting popular as biomechanical energy harvesters to power small electronic devices and as self-powered sensors for pressure, motion, vibration, wind, waves, biomedical information, and chemical substance detections. In this study, the TENG is designed with biocompatible materials, and concentrations of its components have been optimized to generate higher power for application as an energy source and tactile sensor. The process involves using metal-organic frameworks (MOFs), namely MIL-125, with high charge-inducing and charge-trapping capabilities incorporated into the commercial Ecoflex matrix. Electrical characterization demonstrated that the sample with 0.25 wt% MIL-125 (0.25%MOF/Ecoflex) is the optimal concentration in the matrix with an output of up to 305 V and 13 µA, respectively. Moreover, the proposed flexible TENG converts mechanical energy to electrical, with a maximum power density of 150 µW cm⁻² (1.5 W m⁻²), which is more than twice superior to the pristine Ecoflex-based counterparts. The TENG shows robust and stable performance without noticeable degradation during continuous 200,000 cyclic testing. Furthermore, 0.25%MOF/Ecoflex TENG can power small electronic devices such as calculators, humidity sensors, and cardiac pacemakers. A robotic gripper trained via machine learning to identify various objects is also successfully developed with a self-powered 0.25%MOF/Ecoflex TENG sensor.

Cost-effective miniaturized electrodes that maintain a high electroactive surface area (ESA) are needed for the widespread deployment of point-of-care sensors. Cost-effective methods are recently developed to fabricate nanoroughened microstructured gold electrodes (NR-MSEs) with ultrahigh ESA. In this work, the effectiveness of NR-MSEs for bioelectrochemical enzymatic sensors is evaluated. A glucose sensor is constructed by first casting onto NR-MSEs a solution containing reduced graphene oxide decorated with gold nanoparticles, glucose oxidase, and glutaraldehyde, followed by a solution containing ferrocene, and a layer of chitosan to prevent the leakage of sensor components. A urea biosensor is also fabricated using Nafion as a cationic exchanger for the electropolymerization of polyaniline, followed by the deposition of a composite containing urease, bovine serum albumin, and glutaraldehyde. The limit of quantification for both biosensors is below clinically relevant concentrations of the analytes in biofluids, 0.67 mm for glucose and 1.70 mm for urea. The sensors exhibit excellent performance in complex matrixes (human blood serum and wine for glucose and human blood serum and urine for urea), with recovery for spiked analytes in the range of 92–108%. It is anticipated that NR-MSEs will expedite the development of highly sensitive bioelectrochemical sensors for use in resource-limited settings.

The detection and quantification of protein biomarkers in bodily fluids is important for many clinical applications, including disease diagnosis and health monitoring. Current techniques for ultrasensitive protein detection, such as enzyme-linked immunosorbent assay (ELISA) and electrochemical sensing, involve long incubation times (1.5–3 h) and rely on single-use sensing electrodes which can be costly and generate excessive waste. This work demonstrates a reusable electrochemical immunosensor employing magnetic nanoparticles (MNPs) and dually labeled gold nanoparticles (AuNPs) for ultrasensitive measurements of protein biomarkers. As proof of concept, this platform is used to detect C-X-C motif chemokine ligand 9 (CXCL9), a biomarker associated with kidney transplant rejection, immune nephritis from checkpoint inhibitor therapy, and drug-associated acute interstitial nephritis, in human urine. The sensor successfully detects CXCL9 at concentrations as low as 27 pg mL⁻¹ within ≈1 h. This immunosensor was also adapted onto a handheld smartphone-based diagnostic device and used for measurements of CXCL9, which exhibited a lower limit of detection of 65 pg mL⁻¹. Lastly, this work demonstrates that the sensing electrodes can be reused for at least 100 measurements with a negligible loss in analytical performance, reducing the costs and waste associated with electrochemical sensing.

Ultrasound (US), as a non-invasive mechanical wave, has served as a visual tool for medical diagnosis and therapy for echolocation effect, cavitation effect, thermal effect, and generation of reactive oxygen species (ROS) with the aid of sonosensitizers. This review summarizes the history, effects, and biomedical applications of US, and US-assisted cancer therapy is highlighted. The rational combination of US with near-infrared afterglow nanoparticles, anti-tumor prodrugs, and stimuli-responsive nanocarriers, demonstrates the great promise for bioimaging, cancer therapy, and drug delivery, promoting US-related technology in biomedical diagnosis and therapeutics.

Human tactile perception involves the activation of mechanoreceptors located within the skin in response to external stimuli, along with the organization and processing within the brain. However, human sensations may be subject to the issues related to some physiological factors (such as skin injury or neurasthenia), resulting in inability to quantify tactile information. To address this challenge, a novel bio-inspired artificial tactile (BAT) sensing system enabled by the integration of optical microfiber (OM) with full-connected neural network (FCNN) in this paper is demonstrated, inspired by human physiological characteristics and tactile mechanisms. In this system, the BAT sensor mimics human skin, where the OM serves as the mechanoreceptor for sensing tactile stimuli, while the FCNN functions as a simulated human brain to train and extract the signal characteristics for intelligent object recognition. The experimental results indicate that the proposed BAT sensor can sensitively respond to both the contact force (static tactile stimuli), as well as the vibrotactile events (dynamic tactile stimuli) for the recognition of regular textures. Furthermore, by integrating the trained FCNN, the BAT sensing system accurately identifies various intricate surface textures with an exceptional accuracy of 95.7%, highlighting its potential in next-generation human-machine interaction and advanced robotics.

Sensors stand as pivotal cornerstones of technology, driving progress across a spectrum of industries through their ability to precisely capture and interpret an extensive array of physical phenomena. Among these advancements, microwave photonic (MWP) sensing has emerged as a new sensing technique, elevating sensing speed and resolution for practical applications. Integrated MWP sensors exhibit unparalleled capabilities in ultra-sensitive, label-free nanoscale detection, offering the potential to synergize with advanced integration techniques for a compact footprint and versatile designs. This paper reviews and summarizes the development and recent advances in integrated MWP sensing, focusing on the schemes based on microresonators. The diverse array of existing schemes is systematically categorized, elucidating their operational principles and performance demonstration. Furthermore, the assistance of machine learning and deep learning in integrated MWP sensors is explored, highlighting the potential of intelligent sensing paradigms. Finally, current challenges and opportunities aimed at further advancing MWP sensors are discussed.

SARS-CoV-2 Sensing and Detection

In article 2300135, Youssef Tawk and co-workers introduce an advanced portable device that leverages electromagnetic waves and data analytics to instantaneously detect and differentiate between the SARS-CoV-2 virus and different respiratory viruses. It employs a radio frequency (RF) circuit to electromagnetically identify virus signatures in diluted nasopharyngeal swabs with a detection accuracy of 94%, a sensitivity of 95%, and a specificity of 97.5%.