Nanoporous Sensor Research Articles

Transparent, Flexible Nanoporous Sensors with Humidity and Pressure Sensing Capabilities for Sports Health Status Monitoring

Transparent, Flexible Nanoporous Sensors with Humidity and Pressure Sensing Capabilities for Sports Health Status Monitoring

Real-time monitoring of daunorubicin pharmacokinetics with nanoporous electrochemical aptamer-based sensors in vivo

The metabolic differences between patients with the anticancer drug daunorubicin (DRN) pose difficulties in providing clinical delivery strategies for different patients. Therefore, it is urgent to develop a pharmacokinetic platform that can real-time monitor drug levels in vivo to achieve precise drug delivery and reduce drug side effects. To this end, an electrochemical aptamer-based (E-AB) sensor was designed to realize real-time and continuous monitoring of DRN levels in vivo and obtain DRN pharmacokinetics of different individuals for the first. Specifically, the binding free energy of the aptamer to the target was calculated by molecular docking simulations. Using nanoporous gold working electrodes with immobilized aptamers as E-AB sensors, which monitored DRN in the blood of different rat models continuously for many hours with nanomolar precision and second resolution, and hundreds of DRN concentration values were obtained, based on which important pharmacokinetic parameters were simulated and computed, including half-life of drug DRN distribution and elimination, and peak concentration in blood. These parameters help to determine the metabolism of drug DRN in different patients and adjust the administered dose in time to achieve precise treatment. Therefore, this E-AB platform may provide a valuable new tool for clinicians to monitor pharmacokinetics in different patients.

Effect of nanoporous membranes thickness in electrochemical biosensing performance: application for the detection of a wound infection biomarker.

Introduction: Nanoporous alumina membranes present a honeycomb-like structure characterized by two main parameters involved in their performance in electrochemical immunosening: pore diameter and pore thickness. Although this first one has been deeply studied, the effect of pore thickness in electrochemical-based nanopore immunosensors has been less taken into consideration. Methods: In this work, the influence of the thickness of nanoporous membranes in the steric blockage is studied for the first time, through the formation of an immunocomplex in their inner walls. Finally, the optimal nanoporous membranes were applied to the detection of catalase, an enzyme related with chronic wound infection and healing. Results: Nanoporous alumina membranes with a fixed pore diameter (60 nm) and variable pore thicknesses (40, 60, 100 μm) have been constructed and evaluated as immunosensing platform for protein detection. Our results show that membranes with a thickness of 40 μm provide a higher sensitivity and lower limit-of-detection (LOD) compared to thicker membranes. This performance is even improved when compared to commercial membranes (with 20 nm pore diameter and 60 μm pore thickness), when applied for human IgG as model analyte. A label-free immunosensor using a monoclonal antibody against anti-catalase was also constructed, allowing the detection of catalase in the range of 50-500 ng/mL and with a LOD of 1.5 ng/mL. The viability of the constructed sensor in real samples was also tested by spiking artificial wound infection solutions, providing recovery values of 110% and 118%. Discussion: The results obtained in this work evidence the key relevance of the nanochannel thickness in the biosensing performance. Such findings will illuminate nanoporous membrane biosensing research, considering thickness as a relevant parameter in electrochemical-based nanoporous membrane sensors.

A nanoporous screen-printed carbon sensor for environmental and clinical monitoring of the antibiotic ciprofloxacin

A very sensitive, fast and simple electrochemical procedure using a nanoporous screen-printed carbon electrode (NPSPCE) was developed for the determination of the fluoroquinolone antibiotic ciprofloxacin (CFX). Changes in the surface morphology and electrochemical properties of the SPCE before and after pre-anodization were examined using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). CV studies also demonstrated unequivocally adsorption controlled and irreversible oxidation of CFX. Using optimized conditions, the developed procedure is characterized by excellent selectivity and high sensitivity, allowing to achieve a very low limit detection (6.3 × 10−11 mol/L). The measurements taken allow us to consider the NPSPCE as a very effective tool for direct determination of CFX in samples with a complex matrix such as sewage and body fluids. The developed environment friendly sensor and procedure meet the requirements of green chemistry (reduction of toxic chemicals/reagents, and generation of minimal waste).

Application of nanomaterial-modified electrochemical sensors in pesticide residue detection

Nowadays, the frequent application of insecticides leads to pesticide remnants detected in plentiful amounts of many foods, such as fruits and edibles. Even though the remains of the compounds produced by pesticides are tracked, the tremendous toxicity is sufficient to endanger human life and health. Thus, detecting pesticide residue in different vegetable and fruit foods is essential. Determine the number of leftover pesticides in different vegetable and fruit foods to avoid serious illnesses brought about by exposure to pesticides so that people’s physical and mental health and product quality and safety are ensured. Therefore, this article is about nano-porous materials based-electrochemical sensors used to detect pesticide residues in food. This article briefly introduces the mechanism and composition of electrochemical sensors, the classification of electrochemical nanomaterials, and the utilization of nanomaterials in electrochemical sensors. Nano-porous materials have a high specific surface area, adsorption, and catalytic properties to ensure accurate, accurate, and reliable detection. This article discusses metal nanomaterials with variable sizes, shape, surface, and physical and chemical features and their implementation in the detection of electrochemical sensors. It also introduces metal oxide nanomaterials with the characteristics of cheap and easy preparation and the detection range of this material. It also introduces the properties of carbon nanomaterials, carbon nanotubes, graphene, and carbon dots. Subsequently, this article summarizes the progress of nano-porous materials based on electrochemical sensors in pesticide residues. It also introduces the opportunities and challenges that nanomaterial-modified electrochemical sensors will face in pesticide detection and looks forward to reducing the harm of pesticides to the environment and human health in the future.

Nanoporous ZnO structure prepared by HiPIMS sputtering for enhanced ozone gas detection

A high performance ozone gas sensor is fabricated using high power impulse magnetron sputtering (HiPIMS) process with nanoporous ZnO as the sensing material which is deposited on micro electro mechanical systems (MEMS) device. The morphology and nanostructure properties of ZnO were tested with XRD, SEM, TEM, EDS and XPS. As the sensor is tested at different temperatures, the sensor showed high sensing response at 200 °C operating temperature and with 400 °C annealed sample of nanoporous ZnO sensor. Low concentrations of ozone were chosen to obtain best possible sensing response characteristics ranging from 50 ppb to 1000 ppb. At 1000 ppb, sensor recorded a high 638% sensing response at 200 °C optimal temperature. Selectivity test and effects of relative humidity data is presented in the study, where sensor had high selectivity towards O3 gas and the sensing response showed decreasing trend with increase in relative humidity. The reason behind sensing mechanism of the nanoporous ZnO sensor is explained due to the adsorption and desorption phenomenon on the surface of ZnO sensor.

A Wafer‐Scale Nanoporous 2D Active Pixel Image Sensor Matrix with High Uniformity, High Sensitivity, and Rapid Switching (Adv. Mater. 14/2023)

A Wafer‐Scale Nanoporous 2D Active Pixel Image Sensor Matrix with High Uniformity, High Sensitivity, and Rapid Switching (Adv. Mater. 14/2023)

AWafer-Scale Nanoporous 2D Active Pixel Image Sensor Matrix with High Uniformity, High Sensitivity, and Rapid Switching.

2D transition-metal dichalcogenides (TMDs) havebeen successfully developed as novel ubiquitous optoelectronics owing to their excellent electrical and optical characteristics. However, active-matrix image sensors based on TMDs have limitations owing to the difficulty of fabricating large-area integrated circuitry and achieving high optical sensitivity. Herein, a large-area uniform, highly sensitive, and robust image sensor matrix with active pixels consisting of nanoporous molybdenum disulfide (MoS2 ) phototransistors and indium-gallium-zinc oxide (IGZO) switching transistors is reported. Large-area uniform 4-inch wafer-scale bilayer MoS2 films are synthesized by radio-frequency (RF) magnetron sputtering and sulfurization processes and patterned to be a nanoporous structure consisting of an array of periodic nanopores on the MoS2 surface via block copolymer lithography. Edge exposure on the nanoporous bilayer MoS2 induces the formation of subgap states, which promotes a photogating effect to obtain an exceptionally high photoresponsivity of 5.2 × 104 A W-1 . A 4-inch-wafer-scale image mapping is successively achieved using this active-matrix image sensor by controlling the device sensing and switching states. The high-performance active-matrix image sensor is state-of-the-art in 2D material-based integrated circuitry and pixel image sensor applications.

Capacitive response of nanoporous HMDSO film coated interdigited electrodes towards VOCs molecules

In this paper, nano-porous thin films capacitive-type sensors have been fabricated for the detection of volatile organic compounds (VOCs) using the micro sized interdigitated electrodes (IDEs). The sensitive layers were elaborated from hexamethyldisiloxane (HMDSO) using plasma enhanced chemical vapor deposition (PECVD) technique. The choice of HMDSO polymer as sensitive layer is based on its low dielectric constant compared to analytes ones. The sensing performances of plasma polymers were strongly correlated to their chemical and physical properties, which depend directly on the plasma polymerization conditions including monomer pressure. The sensor sensitivity was at its highest value of 0.32, 0.24 and 0.20 pF/ppm towards methanol, ethanol and acetone, respectively, for the device fabricated with the smallest gap (36 µm) and higher monomer pressure (50 Pa). Chemical and morphological structures of the elaborated thin sensitive layers have been investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) and scanning electron microscope (SEM), respectively.

Wearable Dual-Signal NH3 Sensor with High Sensitivity for Non-invasive Diagnosis of Chronic Kidney Disease.

NH3 gas in human exhaled breath contains abundant physiological information related to human health, especially chronic kidney disease (CKD). Unfortunately, up to now, most wearable NH3 sensors show inevitable defects (low sensitivity, easy to be interfered by the environment, etc.), which may lead to misdiagnosis of CKD. To solve the above dilemma, a nanoporous, heterogeneous, and dual-signal (optical and electrical) wearable NH3 sensor mask is developed successfully. More specifically, a polyacrylonitrile/bromocresol green (PAN/BCG) nanofiber film as a visual NH3 sensor and a polyacrylonitrile/polyaniline/reduced graphene oxide (PAN/PANI/rGO) nanofiber film as a resistive NH3 sensor are constructed. Due to the high specific surface area and abundant NH3 binding sites of these two nanofiber films, they exhibit good NH3 sensing performance. However, although the visual NH3 sensor (PAN/BCG nanofiber film) is simple without the need of any detecting facilities and quite stable when temperature and humidity change, it shows poor sensitivity and resolution. In comparison, the resistive NH3 sensor (PAN/PANI/rGO nanofiber film) is of high sensitivity, fast response, and good resolution, but its electrical signal is easily interfered by the external environment (such as humidity, temperature, etc.). Considering that the sensing principles between a visual NH3 sensor and resistive NH3 sensor are significantly different, a wearable dual-signal NH3 sensor containing both a visual NH3 sensor and resistive NH3 sensor is further explored. Our data prove that the two sensing signals in this dual-signal NH3 sensor mask can not only work well without interference with each other but also complement each other to improve the sensing accuracy, indicating its potential application in non-invasive diagnosis of CKD.

AAO-Assisted Nanoporous Platinum Films for Hydrogen Sensor Application

The effects of the porosity and the thickness on the ability of hydrogen sensing is demonstrated through a comparison of compact and nanoporous platinum film sensors. The synthesis of anodic aluminum oxide (AAO) nanotubes with an average pore diameter of less than 100 nm served as the template for the fabrication of nanoporous Pt films using an anodization method. This was achieved by applying a voltage of 40 V in 0.4 M of a phosphoric acid solution at 20 °C. To compare the film and nanoporous Pt, layers of approximately 3 nm and 20 nm were coated on both glass substrates and AAO templates using a sputtering technique. FESEM images monitored the formation of nanoporosity by observing the Pt layers covering the upper edges of the AAO nanotubes. Despite their low thickness and the poor long-range order, the EDX and XRD measurements confirmed and uncovered the crystalline properties of the Pt films by comparing the bare and the Pt deposited AAO templates. The nanoporous Pt and Pt thin film sensors were tested in the hydrogen concentration range between 10–50,000 ppm H2 at room temperature, 50 °C, 100 °C and 150 °C. The results reveal that nanoporous Pt performed higher sensitivity than the Pt thin film and the surface scattering phenomenon can express the hydrogen sensing mechanism of the Pt sensors.

Long-Term Durability and Cycling of Nanoporous Materials Based Impedance NO2 Sensors

Nanoporous materials, including metal–organic frameworks (MOFs) and inorganic zeolites, are gaining attention as gas sensor materials due to their chemical selectivity and robustness. To advance industrial viability of these materials as sensors, long-term, variable environment testing is needed to evaluate their stability and continued chemical exposure response. Nanoporous materials-based direct electrical readout sensors were evaluated for 3 months under dry or humid conditions at 74 °C. The sensors were comprised of either Ni-MOF-74, Mg-MOF-74, or Ni-SSZ-13 zeolite. Additionally, we describe the development of multichambered sensor testing platforms that allows uninterrupted direct impedance monitoring of each sensor over long test periods. Results indicate relative stability in dry conditions for the sensors over time. In contrast, degradation of the active sensing material is evident in the humid environment. Collectively, these results demonstrate need for long-term testing of emerging nanoporous sensor materials under specific environmental conditions.

A nanoporous gold film sensor modified with polypyrrole/CuO nanocomposite for electrochemical determination of piroxicam and tramadole

In this paper, an electrochemical sensor was developed to determine piroxicam (PX) and tramadole (Tr) based on their enhanced electrochemical responses at the surface of the polypyrrole/CuO nanocomposite-modified nanoporous gold film (NPGF) electrode. The experimental results showed that PX provide an oxidation peak at 0.65 V in pH = 8.0. The DPV results were linearly affiliated on PX concentration within the two closed windows (C1PX = 0.05–30.0 μM, correlation coefficient of 0.9905, and C2PX = 50.0–300.0 μM, correlation coefficient of 0.9927). From voltammetric curves, the detection limit (LOD = 3Sb/m) for PX at a surface of PPY-CuO-NPGF electrode was appeared to be 0.01 μM. Furthermore, the ability of PPY-CuO-NPGF electrode for simultaneous measurement of PX and Tr was investigated. The suggested sensor shows a long-time stability, good repeatability, and rapid response in the mixture media of PX and Tr.

Dihydropyrano quinoline derivatives functionalized nanoporous silica as novel fluorescence sensor for Fe3+ in aqueous solutions(aq)

A novel nanoporous silica-based fluorescence sensor with high selectivity and sensitivity was successfully prepared via grafting of 3-isocyanatopropyltriethoxysilane and dihydropyrano [3, 2-c] quinoline derivatives (DPQ) onto the pore walls of mesoporous silica. The attachment of fluorophore groups onto the surface of the SBA-15 was approved via TGA and FT‐IR spectroscopy. TGA analysis indicates a large weight loss about 49%, which is attributed to the binding of a large number of organic groups on the pores surface, which functional groups appeared in the FT-IR spectra. Structural characterization techniques have proved the type IV for N2 adsorption-desorption isotherm, which revealed the preservation of the mesoporous structure. Also, low-angle XRD, FESEM and TEM analyses demonstrate the formation of ordered and well-defined 2D hexagonal mesoporous structure (space group p6mm). Whereas, Fe3+ ions caused discernible fluorescence quenching of the fluorescence sensor, the other cations used did not significantly changed fluorescence emission of SBA-Si-DPQ. The fluorescence quenching of the sensor is attributed to the paramagnetic properties of Fe3+ ions that appear by complex formation between the urea group of the probe and Fe3+ ions. It is noteworthy that, the excitation at 310 nm caused an emission with a maximum at 478 nm wavelength. By the increasing concentration of the analytes, the emission intensity was decreased dramatically and good linearity observed between analytes concentrations and the fluorescence intensity quenching of the sensor. The measured detection limits for Fe3+ ions was 2.0 × 10−6 M.

Microneedle-based nanoporous gold electrochemical sensor for real-time catecholamine detection

Dopamine (DA), epinephrine (EP), and norepinephrine (NEP) are the main catecholamine of clinical interest, as they play crucial roles in the regulation of nervous and cardiovascular systems and are involved in some brain behaviors, such as stress, panic, anxiety, and depression. Therefore, there is an urgent need for a reliable sensing device able to provide their continuous monitoring in a minimally invasive manner. In this work, the first highly nanoporous gold (h-nPG) microneedle-based sensor is presented for continuous monitoring of catecholamine in interstitial fluid (ISF). The h-nPG microneedle-based gold electrode was prepared by a simple electrochemical self-templating method that involves two steps, gold electrodeposition and hydrogen bubbling at the electrode surface, realized by sweeping the potential between + 0.8 V and 0 V vs Ag/AgCl for 25 scans in a 10 mM HAuCl4 solution containing 2.5 M NH4Cl, and successively applying a fixed potential of − 2 V vs Ag/AgCl for 60 s. The resulting microneedle-based h-nPG sensor displays an interference-free total catecholamine detection expressed as NEP concentration, with a very low LOD of 100 nM, excellent sensitivity and stability, and fast response time (< 4 s). The performance of the h-nPG microneedle array sensor was successively assessed in artificial ISF and in a hydrogel skin model at typical physiological concentrations.Graphical abstract

An observational study for detection and quantification of interferon- γ in sweat toward inflammation monitoring

This work demonstrates the quantification and detection of interferon- γ (IFN-γ), a key inflammatory biomarker in sweat using a flexible, nanoporous sweat sensor. IFN-γ is a pro-inflammatory cytokine released during the innate and adaptive response to enable antibacterial/antiviral immunity to an infection. Further, IFN-γ is critical marker to combat cancer through anti-tumor and pro-apoptotic mechanism. Therefore, real-time, continuous monitoring of pro-inflammatory cytokines can aid clinicians in active feedback on the administered therapeutic regimen. However, conventional blood-based laboratory methods are not feasible for continuous monitoring while sweat-based monitoring allows to continuously track the biomarker level in a point-of-need setting. This work demonstrates a sweat sensor device for rapid and accurate detection of IFN-γ in human sweat with less than 10% of variation. Highly sensitive and selective detection of IFN-γ with a limit of detection of 1 pg/mL and dynamic range of 1–512 pg/mL using impedance spectroscopy. The sensor demonstrated minimal to no signal response to non-specific cytokines. The performance of sweat sensor was further validated by comparing to state-of-art reference method and a Pearson's correlation of r > 0.95 was achieved in an observational study comprising of human subject samples confirming the reliability of the sweat sensor to report sweat IFN-γ levels. The promising findings from this work demonstrate the viability of utilizing the detection of IFN-γ in sweat for several inflammatory diseases such as cancer. Detection of IFN-γ in sweat will be pivotal in monitoring and aiding physicians in administering precision treatment strategies for patients diagnosed with cancer through continuous monitoring of immune status.

Low-cost high- performance NO2 sensor based on nanoporous indium tin oxide (ITO) film

The electrochemical corrosion of commercial indium tin oxide (ITO) glasses enabled the preparation of a low-cost nanoporous ITO film-based sensor exhibiting a high NO2 response. The NO2 sensing characteristics of the nanoporous ITO films were studied at different processing voltages and test temperatures. Under the optimal test condition (10 V, 100 °C), the response of the sensor was 3.1 to 0.1 ppm NO2 and 180–500 ppm NO2. Compared with previous literature, the as-obtained sensor has a low working temperature (100 °C), wide detection range (0.1–500 ppm NO2), and high response (12.34 1 ppm NO2). Moreover, the sensor exhibited excellent repeatability and a high selectivity toward NO2. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller was employed to study the structural changes of the ITO film due to electrochemical corrosion and revealed a nanoporous structure with abundant surface hydroxyl groups. The influences of the nanoporous structure and surface hydroxyl groups on the response are discussed in detail. Finally, it was found that the Langmuir model provided a good fit to the working curve of the sensor, and thus explains the mechanism of the enhanced response based on the nanoporous structure. Overall, this study demonstrates that an electrochemically corroded ITO film is suitable for detecting NO2.

A novel and ultrasensitive NH2-MIL-125/silicon nanoporous pillar array-based capacitive humidity sensor

A novel and ultrasensitive NH2-MIL-125/silicon nanoporous pillar array-based capacitive humidity sensor

Highly efficient detection of Tricaine methanesulfonate based on the nanoporous gold electrochemical sensor

Tricaine (MS222) is a widely-used compound in fish anesthesia in aquaculture, transportation, and research laboratories, but its use has certain safety risks due to the lack of relevant laws and regulations. Herein, a simple and efficient one-step corrosion method was used to prepare a nanoporous gold (NPG) electrochemical sensor for detecting MS222. Under 0.1 M H2SO4 buffer solution, NPG showed a strong electrocatalytic redox effect on MS222, a wide linear range of 5 μg·mL−1 ~ 100 μg·mL−1, a low detection limit of as low as 0.29 μg·mL−1, and good applicability in actual sample of the recovery rate as 94.89%~107.93%. Thus, this work demonstrates the basic advantages of NPG and provides good application potential for the rapid detection of fishery anesthetic MS222.

Nanoporous Carbon Aerogels for Laser-Printed Wearable Sensors

Laser-induced porous carbon materials have received growing attention as electrodes in micro-supercapacitors, electronics, and biosensors. Herein, resorcinol-formaldehyde (RF) aerogel is used for laser carbonization and activation to produce a nanoporous black conductive surface with high porosity and a specific surface area of 703 m2·g–1 as well as high absorbance to infrared light (∼98%). Furthermore, inspired by the photoreception behavior of octopus arms, a “thunder motif” nanoporous carbon aerogel-based resistance-type sensor is able to be laser-printed on paper-reinforced RF aerogel, which shows high integration of temperature (0.19%·°C–1), strain (gauge factor 16.7), humidity, and especially infrared light (0.12%·mW–1, which is not common for a normal on-skin sensor) sensing in one device and better performance than a serpentine layout sensor. With its good flexibility and biodegradability, this multifunctional sensor can serve as an on-skin wearable sensor that can sense gesture changes and breathing.