Sensors and Actuators Reports最新文献

Polydimethylsiloxane (PDMS) is widely used as the substrate for wearable sensors and elastomeric actuators because of its good dielectric property, stretchability, thermal/chemical resistance, biocompatibility, and transparency. PDMS-based stretchable sensors and electroactive actuators need a coating of thin compliant electrodes. However, PDMS is hydrophobic with water contact angle above 120°. Such low surface energy of PDMS creates issues for uniform coating of ink-based electrodes and/or their adhesion. Similarly, metal thin-film or nanowire-based materials coated on PDMS easily peels off. Surface treatments like UV/plasma exposure can temporarily increase PDMS's surface energy. However, these surfaces return to its original state within hours leaving behind a brittle surface layer that cracks upon stretching. To address these issues, we formulated a viscous composite ink with PEDOT:PSS and PDMS that can easily be coated on untreated PDMS by blade casting, screen printing, and so on. These coatings are highly transparent, stretchable, electrically conductive and work as compliant electrodes. We fabricated transparent dielectric elastomer actuators by coating PEDOT:PSS/PDMS composite ink on Elastosil (PDMS) substrates. The actuation strain and breakdown-fields were slightly lower compared to DEA with conventional graphite electrodes. However, the additional self-clearing capability of PEDOT:PSS/PDMS electrodes enhanced robustness of the DEA in events of localized dielectric breakdown.

Molecular tethers that mediate the immobilization of receptors to the sensor surface, carry critical ability to influence sensor outcomes by determining how the receptors are presented to the analyte in the biological medium. An aspect that has however been less explored is the role of flexibility of such tethers in enhancing the efficiency of analyte capture by the receptor, by enhancing its ability to “seek” the analytes in solution. In the enclosed study, we show the length and flexibility of PEG tethers to have a strong influence on the binding of gold nanoparticles (AuNP) or neutravidin (NAv) to tethered amine or biotin receptors respectively. The qualitative similarity in the influence of the tethers, despite the largely dissimilar interactions that drive binding of AuNPs and NAv implies a generic influence at play. The impact of tether length or flexibility is decoupled from that of the density and conformation of tethers, using real-time, quantitative measurements performed using quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) sensors. Substituting neutravidin with neutravidin-conjugated gold nanoparticles accentuated the impact of the tether length, providing additional possibilities to harness the benefits of flexible tethers by increasing the analyte valency. The results emphasize the opportunity to enhance sensor performance by factoring in the influence of tether structure into the design of the sensor interface.

To maintain human and environmental health, it is essential to detect toxic gases. Over the years, researchers have often focused on industrial waste gases like CO, NO₂, H₂S, and NH₃. These hazardous gases can be detected by gas sensors.The conducting polymer, which has shown tremendous promise in room-temperature chemical gas detection due to the fact that its electrical conductivity may change when exposed to oxidative or reductive gas molecules, is one promising material for this sensor. Although in some circumstances, the decreased conductivity and significant attraction to volatile organic compounds and water molecules restrict sensitivity, stability, and gas selectivity, making them unsuitable for use as gas sensors. Inorganic sensitive materials provide various advantages in gas sensors, such as high sensitivity, rapid response to low-concentration analytes, a vast surface area, and changeable surface chemistry, which may supplement the sensing capabilities of conducting polymers. Along with their synergistic effects, there is a great deal of interest in combining inorganic sensitive materials with polymers for gas detection. This review focuses on the development of composite conducting polymers as gas-sensing materials. The implications of several factors affecting sensor performance, such as responsiveness, gas concentration, reaction time, and recovery time of conducting polymers, are highlighted. The function of inorganic nanomaterials in enhancing the gas-sensing performance of conducting polymers is discussed, as well as the development of conducting-inorganic composites including metal oxides, metal, and (carbon nanotube, and graphene. A comprehensive outlook on the topic of gas sensors containing conducting polymer-inorganic composites is delivered.

In this work, poly(N,N-diethylacrylamide) (PDEA) hydrogel films were polymerized on glassy carbon (GC) electrode surface, and isoniazid (INH) was chosen as an electroactive pharmaceutical molecule probe, aiming to investigate the switchable electrochemical behaviors of INH. Determining the contents of INH tablets under different external stimuli conditions and constructing its logic gate computing systems. The triple-sensitive electrochemical CV behaviors of INH on this film system toward pH, temperature and salt concentration were observed and explored. Thus, a 3-input/8-output combinational pharmaceutical logic gate network and a 3-to-8 decoder were designed and constructed based on the stimulus-responsive characteristics of the electrochemical response of INH on PDEA hydrogel-modified electrodes. Besides, the relationship between the oxidation peak current (I_pa) and concentration of INH (C_INH) was studied by the differential pulse voltammetry (DPV) method. Apply this film system, and the INH tablets could be switchable detected. The construction of the logic-gate computing system based on isoniazid drug molecule may provide a novel approach and model to design new style drug sensors, which might be applied to intelligent medical diagnostics and drug release.

Enhancing the stability and sensitivity of electrochemical biosensors is highly significant for their practical application. Herein, inspired by the formation of mussel foot protein, we proposed a strategy to construct a hemoglobin-based biosensor for hydrogen peroxide detection using a hydrophobic ionic liquid (HIL) coordination assisted microfluidic technology. The active layer HIL@Hb was achieved by mixing BBimPF₆ (HIL) and Hb via a microfluidic channel, in which HIL helps to maintain the conformational dynamic mobility of hemoglobin (Hb), while the coordination process in a microfluidic reactor prevents aggregation of Hb. Further, the electrode surface was modified with ultra-thin MXene-Ti₃C₂ nanosheets to ensure the effective adhesion of active layer and collection of sensing signals, thus improving the sensitivity of the sensor by synergistic catalysis. Experimental results demonstrate that our designed sensor has good repeatability and stability, which can retain 93% of the initial current response after 30 uses and about 90.11% of its primary current response to H₂O₂ after 30 days. And it has a good linear response range of 1.996–27.232 μM, detection limit reaching 1.996 nM (signal-to-noise ratio, S/N = 3), sensitivity of 52.08 μA·μM⁻¹·cm⁻². Overall, this research offers a facile and effective strategy for constructing a stable biosensor to effectively detect hydrogen peroxide.

Here, we demonstrated the application of a closed bipolar electrode to measure the change in open circuit potential (OCP) of Prussian blue/white as a function of [Cl⁻] concentration independently of electrode surface area. In this bipolar scheme, a potentiostat holds a constant voltage across two separate cells linked by a shared electrode that is sensitive to [Cl⁻] on one end and electrodeposited by Prussian blue on the other. As [Cl⁻] is added to the sample compartment, the ion associates with Ag⁺ to produce Ag/AgCl, altering the junction potential. This change is balanced electrochemically by a shift in the ratio of Prussian blue/Prussian white. A second potentiostat is used to monitor these changes over the Prussian blue electrode, yielding a for the quantification of chloride. We measured a range of 1.0 mM – 55 mM [Cl⁻] over various electrode surface areas, demonstrating that the signal response is independent of electrode area. Additionally, the system had the capability to translate signal across a single bipolar electrode while using differently sized electrodes in each compartment, a property that could be beneficial for microarrays or signal amplification.

Aflatoxins (AF) are fungal toxins which not only contaminate food, but also adversely impact human health if consumed and serve as biomarkers for deadly diseases like liver cancer. Therefore, there is a strong need to develop ultra-sensitive AF detection method in physiological environments. In the present study, ternary transition metal sulfides single crystals (Mn_0.02Ta₃S₆ and Fe₀.₆₅Ta₃S₆) were grown, exfoliated to thin layered nanosheets (NSs) followed by polyethylene-glycol modification (PEG@NSs). High fluorescence quenching abilities towards the aptamers for AF biosensing were demonstrated using PEGylated NSs. It has been observed that PEGylated NSs improves the detection sensitivity ∼ 248 times better than non-PEGylated NSs. Subsequently, multiplexed detections of aflatoxin B1 (AFB1) and M1 (AFM1) in diverse mediums including PBS buffer (1 ×), milk and human serum were performed by employing PEG@Mn₀.₀₂Ta₃S₆ NSs with TAMRA dye-labelled AFB1 aptamer and FAM dye-labelled AFM1 aptamer, respectively. The fluorescence intensity of designed sensor exhibited ultrasensitive detections (∼ pM) and a wide linear range (≥ 5 orders). Hence, the present study can serve as a unique platform for facile, ultra-sensitive, selective, cost-effective and quick multiplexed detection of food toxins and disease biomarkers in complex-matrix.

At present, traditional magnetic field sensors have shortcomings such as large size, complex structure, poor anti-interference ability, and low sensitivity, which are limited in large-scale applications. The magneto-optical sensor has the characteristics of small size, high-integration, stable and reliable in extreme working environment and high sensitivity, which can effectively overcome the above defects and easier to convert it into application products. In this paper, we summarize the magneto-optical sensor based on different used materials, include magnetostrictive materials and magneto-optical materials. We analyzed the sensing mechanisms of these two magneto-optical sensors in detail. The characteristics, structure and performance of magneto-optical sensors are analyzed, the current research progress is summarized, the future development direction of magneto-optical sensors is proposed, and the challenges and development prospects of magneto-optical sensors are analyzed.

Herein, nitrogen-doped CDs (NCDs) were synthesized in a hydrothermal microwave-assisted pyrolysis using citric acid and urea. Differing carbon-to-urea molar ratios were used and the pH-dependent fluorescence and quantum yield (QY) at various pHs were measured. All NCDs demonstrated pH-dependent fluorescence with increased fluorescence from pH 1-13. Overall, the NCDs with a carbon-to-dopant molar ratio of 1:6 demonstrated the highest QY of 19% in pH 11. Additionally, high quantum yields were observed between pH 7-11. Therefore, NCDs, as prepared, may serve as cost-effective fluorescent pH sensors or in bioimaging applications.

Skin grafting is one of the most frequently performed surgical procedures in dermatology. Nevertheless, the failure rate is still quite high, which can cause a huge burden for patients and the health care system. Early interventions, like salvage surgery, can rescue the grafts that are going to fail. Therefore, real-time and objective monitoring of skin grafts and flaps is crucial to guide clinicians for an evidence-based treatment. This can be achieved by modern sensor applications using advanced techniques in nanotechnology and material science. This review provides an overview on current challenges for the further development of (bio-)sensors for monitoring the uptake of implanted skin grafts and skin flaps. Special interest has been given to invasive/non-invasive as well as wearable/implantable applications. In addition, the adaptation of recent developments in alternative sensing systems with physical, optical and electrochemical transducers for the continuous monitoring (intra- and post-operative) of skin transplants has been discussed.