Advanced Sensor Research最新文献

Rapid and accurate detection of fentanyl in unknown products and aqueous samples can find the unexpected existence of the toxic chemical and assist law enforcement. In this paper, novel colorimetric biosensors for fentanyl and one of its metabolites, norfentanyl, are designed and fabricated by incorporating an enzyme-linked immunosorbent assay (ELISA) onto three dimensionally macroporous framework melamine foam (MF). The MF-based ELISA sensors (f-ELISA) have performance features of ultrahigh sensitivity, selectivity, and on-site detection without using any laboratory instruments. The lowest visually distinguishable concentration of fentanyl in wastewater is 0.005 mg L⁻¹ by naked eye and can be further improved to 0.001 mg L⁻¹ with the aid of a smartphone. Furthermore, by increasing sample volume, the sensitivity of the f-ELISA sensor can reach naked-eye detection of fentanyl at concentrations as low as 0.0005 mg L⁻¹, a volume-responsive signal enhancement, and a special structural advantage provided by the macroporous structure of the foam. The norfentanyl f-ELISA sensor can reveal a lowest visually distinguishable concentration of 0.001 mg L⁻¹ in PBS buffer for both naked-eye and smartphone analysis. The new biosensors can overcome limitations of current techniques in detecting fentanyl and its derivatives in fluids and are suitable for on-site use.

Microelectromechanical system (MEMS) sensors based on piezoresistive elements are widely used in various applications due to their high sensitivity and compact size. Traditionally, silicon-based MEMS devices have been fabricated using lithography-based processes, with piezoresistive layers formed through thermal diffusion or ion implantation. However, these processes involve complex fabrication workflows. In response, laser fabrication techniques, such as laser micromachining and laser annealing-based impurity diffusion, have attracted attention. In this study, a laser-based approach for fabricating a silicon piezoresistive cantilever using nanosecond-pulse laser annealing is proposed. The proposed process integrates two steps: localized laser annealing for impurity doping and the formation of a partially 3D cantilever structure through laser cutting and etching. All the fabrication steps are performed using a single-laser processing system, enabling direct-write patterning and automatic alignment of the piezoresistive layer with the sensor structure without lithography. In this paper, the effectiveness of the proposed method is evaluated through electrical and mechanical characterizations of the fabricated sensor. The fabricated piezoresistive layer exhibits a gauge factor exceeding 15, indicating that the sensor is sufficiently effective for practical use.

Molecularly imprinted polymers (MIPs) are synthetic alternatives to biological recognition elements like antibodies and are commonly used in developing electrochemical biosensors. However, comprehensive mechanistic studies of electrochemical detection methods on identical platforms remain scarce. This study fills this gap by creating an electropolymerized MIP (e-MIP) on a single electrode (e-MIP/SE) and systematically comparing differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) for protein sensing. Cystatin-C (Cys-C) is used as a model protein for both molecular imprinting and sensing. Polybithiophene-based recognition layers are directly formed on gold electrodes using a carboxylic acid-derivatized bithiophene crosslinker and a bithiophene monomer under potentiostatic conditions. Morphological and spectroscopic analyses confirm the uniformity of the functional cavity-enriched e-MIP films, which are ≈2.5 µm thick. The electrochemical comparison shows that DPV outperforms EIS, with detection and quantification limits of 0.19 µg mL⁻¹ (≈15 nM) and 0.64 µg mL⁻¹ (≈49 nM), respectively, and excellent linearity (R² = 0.99). The superior performance of DPV results from an enhanced signal-to-noise ratio due to suppression of capacitive current. Overall, this work provides a mechanistic understanding of electrochemical protein detection strategies using e-MIP/SEs, employing a methodology adaptable for detecting various protein targets.

A novel inorganic–organic nanocomposite material composed of multi-walled carbon nanotubes (MWCNTs), polyoxometalates (POMs), and aptamers is presented for the electrochemical detection of target molecules in aqueous environments. The responsive POM–aptamer units are synthesized via a strain-promoted azide–alkyne cycloaddition (SPAAC) reaction, covalently linking a single-stranded DNA (ssDNA) aptamer to the Lindqvist-type hexavanadate [V₆O₁₃((OCH₂)₃CCH₂N₃)₂]²⁻ (V₆-N₃) through a triazole bridge. These conjugates are immobilized onto amine-functionalized MWCNTs and drop-casted onto a platinum microelectrode surface to form a “Pt//MWCNT/POM–aptamer” heterostructure. The sensor is evaluated using diclofenac, a pharmaceutical pollutant, as a model analyte. By combining the molecular recognition capabilities of aptamers with the redox properties of POMs and the excellent electrical conductivity of MWCNTs, the hybrid sensor demonstrates significantly enhanced electrochemical sensitivity. This sensing platform shows great potential for application in decentralized medical devices for rapid ex-vivo diagnostics of complex biological matrices such as blood.

Human-Machine Interface

In article 2500012, Gursel Alici, and co-workers introduce a textile-based micro-structured pressure sensor with excellent sensitivity, resolution, linearity, and accuracy. Integrated into a 4-channel capacitive-based force myography (cFMG) armband, this wearable system enables accurate muscle activity monitoring and hand gesture recognition for advanced assistive devices and interactive human-machine interface (HMI) applications.

The global health landscape is continually challenged by infectious diseases that can swiftly escalate into pandemics, underscoring the need for rapid, accurate, and cost-effective diagnostic technologies. CRISPR-based diagnostics (CRISPR-Dx) has emerged as a promising solution, offering high sensitivity, specificity, and adaptability for pathogen detection. Recent advances leverage paper-based devices to integrate sample preparation, amplification, and CRISPR-mediated detection into compact, user-friendly formats. These systems exploit paper's inherent advantages—low cost, ease of fabrication, and minimal fluid-handling requirements—to support molecular assays that generate clear visual readouts. Notable developments span from simple dipstick tests to fully integrated point-of-care (POC) platforms, each designed to address real-world constraints such as limited resources and minimal operator training. While significant strides have been made in reagent stabilization, automation, and preamplification-free protocols, several challenges remain. Ensuring robust performance in complex samples, reducing contamination risks, and achieving true POC readiness without specialized equipment are key hurdles. As CRISPR-based paper diagnostics continue to mature, ongoing innovations in device engineering, reagent stabilization, and multiplexing will be essential for commercialization and broader clinical impact. This review discusses the current state of CRISPR-based paper assays, highlights major technical breakthroughs, and explores strategies for realizing their full potential as commercially accessible POC diagnostics worldwide.

Liquid gate-all-around (LGAA) field-effect transistor (FET) biosensors represent advanced material device structures responding electrically to surface potential change and allowing ultra-high sensitivity to biochemical liquids and human bodily fluids. However, the origin and physical working mechanisms for such a type of signals in different complex biochemical solutions remain still many opened questions. Here, noise spectroscopy and impedance methods are applied to study liquid–solid interface properties in LGAA FETs working in adjusted physiological solutions of different pH values. High-quality liquid LGAA Si nanowire (NW) FET biosensors demonstrate the high electronic performance of I–V characteristics in good agreement with modeling data. Impedance spectroscopy measurements allow for analyzing the double-layer capacitances and ion behavior under different pH conditions. Moreover, the noise spectra of the current fluctuations in the biosensors for several solutions are analyzed at different applied liquid-gate and drain-source voltages. The results demonstrate accurate detection of the dynamic ion processes on the nanowire surface. Charge inversion effect is revealed in single-valent ion solutions. Tiny signal characterization results obtained using the LGAA NW FET biosensors provide broader insights into the optimization of sensor parameters for biomedical molecular detection.

Chromogenic and fluorogenic substrates are important for the detection of enzymatic activity. Conjugates of 4-nitrophenol are among the earliest investigated classes of molecules and have been used in diagnostic applications, including those for type-2 diabetes. The detection of 4-nitrophenol under physiological conditions enables real-time monitoring of glucosidase activity. This becomes possible when the resonance structure of 4-nitrophenol is altered, making it distinguishable from its precursor chromogenic substrate. One of the surface-modified silica materials, comprising an acetyl-protected mannoside along with precipitated byproducts such as acyl-urea and urea formed during carbodiimide coupling, induces a unique resonance shift in 4-nitrophenol upon interaction. Raman microscopic analysis can distinguish the phenol-type band at 1330 cm⁻¹ and the quinone-type band at 860 cm⁻¹, thereby enabling monitoring of the α-glucosidase reaction.

Metal halide perovskites (MHPs) are emerging as promising candidates for gas sensing due to their tunable optoelectronic properties, room temperature operation, and scalable fabrication. In this work, hydrogen (H₂) sensing capabilities of methylammonium lead iodide (MAPI) thin films via photoluminescence (PL) spectroscopy is investigated. MAPI films demonstrate a consistent and rapid PL intensity response in a matter of seconds upon exposure to H₂, characterized by an initial increase followed by a decay below baseline, which recovers in ambient air. This reversible behavior is preserved over multiple cycles over an hour, indicating reusability. The magnitude and duration of the PL response vary with H₂ concentration, demonstrating the sensor's ability to detect not only presence but also quantity of gas. Control experiments using encapsulated films confirm specificity to H₂, and X-ray Diffraction (XRD) analysis confirm the interaction does not cause any significant crystallographic changes. Further analysis with thinner films and mixed-halide compositions suggests that both surface and bulk interactions, as well as defect-mediated processes, contribute to sensing. This study establishes MAPI as a viable optical sensor for H₂ gas with fast response, sensitivity to concentration, and potential for low-cost implementation.