Advanced Sensor Research最新文献

Solid-state nanopore sensors, a type of resistive pulse sensing, achieve optimal signal-to-noise performance with a single nanopore. However, the processes involved in solid-state nanopore fabrication and subsequent measurements frequently lead to the formation of multiple nanopores, posing a challenge for precise detection. To address this issue, here, a novel and expedient technique to verify the presence of a single nanopore on a chip is developed. The methodology includes measuring the nanopore's conductance in solutions of various salt conditions, followed by a comparison of these results against a theoretical conductance model. This comparison is instrumental in distinguishing between single and multiple nanopores. Additionally, the study delves into various factors that influence the conductance curve, such as deviations in pore shape from the standard circle and inconsistencies in pore diameter. This approach significantly enhances the practical application of low-cost nanopore preparation techniques, particularly in scenarios like controlled breakdown nanopore fabrication, where the formation of multiple nanopores is a common concern.

The strongly growing interest in digitalizing society requires simple and reliable strain-sensing concepts. In this work, a highly sensitive stretchable sensor is presented using a straightforward and scalable printing method. The piezoresistive sensor consists of conductive core–shell microspheres embedded in an elastomer. As the elastomer, ethylene vinyl acetate (EVA) is employed as an efficient and cost-effective alternative compared to polydimethylsiloxane (PDMS). EVA allows for a significantly lower percolation threshold and low hysteresis compared with PDMS. Using 35 µm microspheres, a detection limit of 0.01% is achieved. When using 4 µm microspheres, the sensor shows a detection limit of 0.015% and electromechanical robustness against 1000 cycles of 0–1% strain. The stretchable strain sensor is successfully implemented as an impact sensor and a diaphragm expansion monitoring sensor. Fast (20 ms) and high-resolution response as well as mechanical robustness to strain values greater than the linear working range of the sensor are demonstrated. The results of this research indicate the promising potential of employing conductive microspheres embedded in the EVA matrix for fast and precise strain detection applications.

Early intervention in acute myocardial infarction can minimize myocardial damage and improve patient survival. Herein, a low-cost device-free portable immunobiosensing platform for flexible monitoring of immediate myocardial infarction is reported. CuS-Pt nanofragments (CuS-Pt NFs) with high photothermal conversion efficiency (≈26.41%) are synthesized by liquid-phase polarity-mediated synthesis. The CuS NFs are loaded in situ with platinum (Pt) nanoreactors using a solvothermal reduction strategy, which is employed to enhance the efficiency of gas production. The resulting CuS-Pt nanocatalysts are encapsulated within liposomes for signal cascade amplification. Specifically, cardiac troponin I (cTn I), a target biomarker in serum, is captured on pre-modified microtiter plates and formed into a classical sandwich model. The thermo-chemically kinetically enhanced CuS-Pt reactor is released through a one-step chemical treatment and transferred to a closed gas generator. Under the excitation of a near-infrared laser emitter, the internal pressure in the gas generator device increases with time and drives the carbon quantum dot solution in the connected hose. The moving distance shows a correlation with the target concentration. This work provides a new implementation for the development of low-cost, efficient pressure immunosensors without the requirement of a readout device.

Hydraulic fluid power systems are essential for a range of engineering applications such as transportation, heavy industry, and robotics. The scale of the industry is such that hydraulic pumps are estimated to account for 15% of all the energy consumption in the European Union and yet the average efficiency of fluid power systems is only 22%. The digitalization of hydraulic systems offers significant advantages in terms of energy efficiency, performance, reduced maintenance, and automation. However, this requires advances in the integration of smart sensing technologies to provide real-time feedback on the operation and health of hydraulic components. This review details developing trends in hydraulic fluid power research and provides an overview of progress related to the digitalization of these systems and their integration within an Industry 4.0 framework. The fundamentals of relevant sensor technologies and innovative approaches for integrating sensors into hydraulics systems are discussed. Methods to deliver power to the sensors and associated electronics through harvested pressure ripples are also reviewed. An outlook with respect to future directions in this field is given, including an assessment of the potential for exploiting advanced manufacturing technologies, in particular additive manufacturing, to facilitate successful sensor integration into hydraulic fluid power systems.

Lipid droplets (LDs) are dynamic cellular organelles that play an essential role in lipid metabolism and storage. LD dysregulation has been implicated in various diseases. However, investigations into the cellular LD dynamics under disease conditions have been rarely reported, possibly due to the absence of high performing LD imaging agents. Here a novel fluorogenic probe, AM-QTPA, is reported for specific LD imaging. AM-QTPA demonstrates viscosity sensitivity and aggregation-induced emission enhancement characteristics. It is live cell permeable and can specifically light up LDs in cells, with low background noise and superior signals that can be quantified. After validation in cell model with LD accumulation induced by oleic acid treatment, AM-QTPA is applied in a small proof-of-concept number of human fibroblast samples derived from people diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), a complex and debilitating disease with unknown cause. The results indicate the presence of larger but fewer LDs in ME/CFS fibroblasts compared to the healthy counterparts, accompanying with frequent LD-mitochondria contacts, suggesting potential upregulation of lipolysis in ME/CFS connective tissue like fibroblasts. Overall, AM-QTPA provides new understanding of the anomalous LD dynamics in disease status, which, potentially, will facilitate in-depth investigation of the pathogenesis of ME/CFS.

Designing advanced soft robots with soft sensing capabilities for real-world applications remains challenging due to the intricate integration of actuation and sensor capabilities, which require diverse materials and complex procedures. This paper introduces a fabric-based robotic technology featuring an “all textile-based self-sensing pneumatic actuator” and a low-cost resistive strain sensor created through simple sewing techniques. The novel approach eliminates the need for additional strain-limiting woven fabric, simplifying the manufacturing process. It also enables the development of bioinspired motions such as bending, twisting, and snake-like movements. The electromechanical behaviors of the sensor and bending actuator are tested for their performance under positive air pressure. Through mathematical modeling, the actuator's sensing capacity is estimated accurately, providing precise feedback for pressure and position control. Different closed-loop controller types, including On–Off and Proportional Integral Derivative (PID) control, are evaluated for their effectiveness. Furthermore, the practical application of the sensing actuator is demonstrated by integrating it into a wearable glove, showcasing its enhanced sensing capabilities for finger-like soft wearable robotic applications. This research tackles the challenges associated with designing advanced soft robots with integrated sensing capabilities, offering a promising fabric-based solution that can drive significant advancements in real-world applications.

3D-Printed Wearable Sensors

In article 2300137, Tyler R. Ray and co-workers review the latest advancements in the additive manufacture of wearable devices for physiological health monitoring to highlight the transformative potential of 3D printing to address some of the persistent disparities in healthcare that disproportionately affect underserved and vulnerable populations by expanding access to state-of-the-art sensing technology.

This study investigates the development of thermoplastic polyurethane (TPU) filaments incorporating multi-walled carbon nanotubes (MWCNT) to enhance strain-sensing capabilities. Various MWCNT reinforcement ratios are used to produce customized feedstock for fused filament fabrication (FFF) 3D printing. Mechanical properties and the piezoresistive response of samples printed with these multifunctional filaments are concurrently evaluated. Surface morphology and microstructural observations reveal that higher MWCNT weight percentages increase filament surface roughness and rigidity. The microstructural modifications directly influence the tensile strength and strain energy of the printed samples. The study identifies an apparent percolation threshold within the 10–12 wt.% MWCNT range, indicating the formation of a conductive network. At this threshold, higher gauge factors are achieved at lower strains. A newly introduced Electro-Mechanical Sensitivity Ratio (ESR) parameter enables the classification of composite behaviors into two distinct zones, offering the ability to tailor self-sensing structures with on-demand properties. Finally, flexible structures with proven application in soft robotics and shape morphing are fabricated and tested at different loading conditions to demonstrate the potential applicability of the custom filaments produced. The results highlight a pronounced piezoresistive response and superior load-bearing performance in the examined structures.

Organic electrochemical transistors (OECTs) excel at biosensing due to their high amplification factor, which allows for detecting low analyte concentrations and picking up weak physiological signals. One prominent use of OECT is in enzymatic metabolite sensing, with the OECT claimed to have a superior low limit of detection and enhanced sensitivity compared to conventional two or three electrode-based setups. However, there has yet to be a direct comparative study on the performance metrics of these sensor configurations under unified conditions. Here, the glucose sensing performance of an enzyme-immobilized electrode is systematically examined in two types of devices that have the same geometrical relations: the first one is a traditional 2- or 3-electrode configuration where the sensing electrode is the working electrode, and in the second one, the enzymatic electrode serves as the gate electrode of an OECT. While benchmarking the performance of OECT technology for enzyme-based metabolite sensing, this study provides insights into the operation mechanism of OECT-based enzymatic sensors. These results can help to design more efficient OECT-based circuits to transduce biological events that involve redox reactions.