Sensitive Sensor Research Articles

Flexible Vibration Sensors with Omnidirectional Sensing Enabled by Femtosecond Laser-Assisted Fabrication

Vibration sensors are integral to a multitude of engineering applications, yet the development of low-cost, easily assembled devices remains a formidable challenge. This study presents a highly sensitive flexible vibration sensor, based on the piezoresistive effect, tailored for the detection of high-dynamic-range vibrations and accelerations. The sensor’s design incorporates a polylactic acid (PLA) housing with cavities and spherical recesses, a polydimethylsiloxane (PDMS) membrane, and electrodes that are positioned above. Employing femtosecond laser ablation and template transfer techniques, a parallel groove array is created within the flexible polymer sensing layer. This includes conductive pathways, and integrates stainless-steel balls as oscillators to further amplify the sensor’s sensitivity. The sensor’s performance is evaluated over a frequency range of 50 Hz to 400 Hz for vibrations and from 1 g to 5 g for accelerations, exhibiting a linear correlation coefficient of 0.92 between the sensor’s voltage output and acceleration. It demonstrates stable and accurate responses to vibration signals from devices such as drills and mobile phone ringtones, as well as robust responsiveness to omnidirectional and long-distance vibrations. The sensor’s simplicity in microstructure fabrication, ease of assembly, and low cost render it highly promising for applications in engineering machinery with rotating or vibrating components.

Design and Application of Uniaxially Sensitive Stress Sensor

Current stress sensors for microsystems face integration challenges and complex signal decoding. This paper proposes a real-time uniaxially sensitive stress sensor. It is obtained by simple combinations of bar resistors using their sensitivity differences in different axes. With the aid of a Wheatstone bridge, the sensor can measure the uniaxial stress magnitude by simple calibration of the stress against the output voltage and detect the bidirectional stress magnitude and direction in a micro-zone by simple rotation. The theoretical sensitivity obtained from simulation is 0.087 mV/V·MPa when the X-bridge is stressed in the X-direction under 1 V of excitation, and the test sensitivity of the X-bridge prepared in this paper is 0.1 mV/V·MPa. The design is structurally and procedurally simple, exhibits better temperature stability, and reduces interface requirements, making it suitable for the health monitoring of multi-chip microsystem chips.

Wearable Sensors for Plants: Status and Prospects

The increasing demand for smart agriculture has led to the development of agricultural sensor technology. Wearable sensors show great potential for monitoring the physiological and surrounding environmental information for plants due to their high flexibility, biocompatibility, and scalability. However, wearable sensors for plants face several challenges that hinder their large-scale practical application. In this review, we summarize the current research status of wearable plant sensors by analyzing the classification, working principles, sensor materials, and structural design and discussing the multifunctional applications. More importantly, we comment on the challenges the wearable plant sensors face and provide our perspectives on further improving the sensitivity, reliability, and stability of wearable plant sensors for future smart agriculture.

A Highly Sensitive Strain Sensor Based on Hook-Shaped Core Long-Period Fiber Grating

A Highly Sensitive Strain Sensor Based on Hook-Shaped Core Long-Period Fiber Grating

Sensors on Flapping Wings (SOFWs) Using Complementary Metal–Oxide–Semiconductor (CMOS) MEMS Technology

This article presents a framework of using MEMS sensors to investigate unsteady flow speeds of a flapping wing or the new concept of sensors on flapping wings (SOFWs). Based on the implemented self-heating flow sensor using U18 complementary metal–oxide–semiconductor (CMOS) MEMS foundry provided by the Taiwan Semiconductor Research Institute (TSRI), the compact sensing region of the flow sensor was incorporated for in situ diagnostics of biomimetic flapping issues. The sensitivity of the CMOS MEMS flow sensor, packaged with a parylene coating of 10 μm thick to prolong the lifetime, was observed as −3.24 mV/V/(m/s), which was below the flow speed of 6 m/s. A comprehensive investigation was conducted on integrating CMOS MEMS flow sensors on the leading edge of the mean aerodynamic chord (m.a.c.) of the flexible 70-cm-span flapping wings. The interpreted flow speed signals were checked and demonstrated similar behavior with the (net) thrust force exerted on the flapping wing, as measured in the wind tunnel experiments using the force gauge. The experimental results confirm that the in situ measurements using the concept of SOFWs can be useful for measuring the aerodynamic forces of flapping wings effectively, and it can also serve for future potential applications.

Cu doped ceria nanoparticles-rhodamine B as a novel chemiluminescence system and its application for nitrite detection in water and food samples.

Fe, Ni, and Cu doped ceria nanoparticles (CeNPs) were prepared with a simple and one-pot hydrothermal synthesis method. We investigated the chemiluminescence (CL) interaction between these NPs and rhodamine B (Rh B) and found that the highest CL intensity was related to the Rh B- Cu doped CeNPs. We assigned that to the higher catalytic property of Cu doped NPs compared to the others. Cu doped CeNPs have been applied for the first time as a catalyst in chemiluminescence reactions. Rh B- Cu doped CeNPs reaction was introduced as a novel CL system, and its mechanism was studied. Considering the sensitivity, simplicity, portability, and rapidness of the CL methods, we applied the introduced reaction to the development of a CL sensor for nitrite monitoring. In the presence of nitrite, the CL intensity of the system decreased, and there was a linear relationship between the CL intensity and nitrite concentration in the range 0.5-100 µM. Based on this fact, a sensitive and selective CL sensor with the detection limit of 0.2µM was established for nitrite detection in various food and water samples.

Review—Carbon-Based Multi-Functional E-Inks for Full Printed Tattoo-Like Sensing Systems

Abstract This review explores the advancements in carbon-based multifunctional electronic inks (CMFEIs) for the development of fully printed, tattoo-like sensing systems. CMFEIs, comprising materials such as carbon nanotubes (CNTs), graphene, and carbon black, offer a unique combination of biocompatibility, mechanical flexibility, and electrical conductivity, making them ideal for wearable electronic applications. We highlight the synthesis, properties, and applications of these inks in creating sensors for monitoring physiological parameters, such as heart rate, temperature, and sweat composition. Notably, the work emphasizes the development of scalable, low-cost production methods that enable the mass production of these sensors without compromising performance. Additionally, it introduces novel fabrication techniques, such as inkjet printing and roll-to-roll processing, that enhance the resolution and flexibility of the sensors, ensuring their seamless integration with the skin. This review also addresses the environmental impact of CMFEIs, emphasizing their potential for sustainable healthcare and flexible electronics. The findings reveal CMFEIs potential to revolutionize wearable technologies by enabling the creation of highly sensitive, low-cost, and flexible sensors that could be widely used in biomedical monitoring, environmental sensing, and smart healthcare systems. This work presents a transformative outlook on the future of wearable electronics and the integration of CMFEIs in next-generation sensing technologies.

Multiplexed Bio‐detection on an Interferometric Optical Waveguide Assembly

AbstractMultiplexed remote bio‐detection is demonstrated through an optical waveguide assembly coated with interferometric layers. Image conduits (IC)s, composed of 3012 individual cores, are coated with interferometric layers of tantalum pentoxide (Ta2O5) and silica (SiO2) to transform each core into a sensitive sensor. The spectral response of the IC as a function of refractive index (RI) changes is obtained and compared with the simulated one. The experimental sensitivities and resolutions of individual cores of the waveguide are assessed in remote detection mode by imaging through the optical assembly. For 75% of the cores, a sensitivity better than 510%. RIU−1 (RI Unit) is obtained, corresponding to a resolution better than 7 × 10−4 RIU. Furthermore, the coated face of IC is functionalized with two localized arrays of hundred‐micrometer droplets containing two different oligonucleotide (ODN) probes using a polymeric 3D‐printed microcantilever. Hybridization of complementary ODN strands is detected for one of the probes, the second being a negative control. Interaction kinetics are monitored in functionalized areas by grouping several cores or on individual cores. Thus, multiplexed bio‐detection on the surface of an interferometric waveguide is demonstrated for the first time paving the way for applications in multiplex in situ biosensing, and, ultimately, in vivo endoscopic diagnosis.

Research on the Application of Flexible Pressure Sensors in Wearable Devices

The potential applications of transparent, adaptable electronic devices in the human body are driving up demand for them. For flexible and wearable electronics, such as medical surveillance devices and artificial skin, pressure sensing is mandatory. The flexibility and sensitivity of pressure sensors have advanced recently owing to developments in material and device structure. Moreover, their low manufacturing costs enable widespread implementation, leading to promising application prospects. The sensors utilize different materials and structures, including capacitive pressure sensors with ionically charged CFMs, magnetic particle-infused carbon sponges, CNT-PDMS composites, and MoSe2/MWNT combinations. These sensors offer advantages such as high sensitivity, wide pressure-detecting ranges, optical transparency, and energy efficiency. They can detect both large and subtle human movements, from walking and finger bending to breathing and eye blinking. The fabrication methods range from simple and cost-effective processes to more complex techniques like photolithography. Many of the sensors incorporate carbon nanotubes (CNTs) in various forms, exploiting their excellent electrical properties. The review highlights the potential of these sensors for healthcare monitoring, clinical diagnosis, and integration into wearable electronics, emphasizing their flexibility, biocompatibility, and ability to provide real-time, non-invasive measurements of physiological signals. Moreover, their low manufacturing costs enable widespread implementation, leading to promising application prospects.

Study of Bionic Tactile Sensors in Flexible Robots

This research investigates the advancement and implementation of bio-inspired tactile and mechanosensory systems, drawing inspiration from sophisticated biological mechanisms found in nature, particularly human sensory networks and the Venus flytrap's rapid response system. The study demonstrates significant progress in developing highly sensitive and precise sensor technologies that effectively mimic natural sensing capabilities. Through innovative material combinations and structural designs, including hybrid graphene-based platforms and advanced piezoelectric tactile arrays, these sensing systems achieve enhanced detection of mechanical forces, subtle vibrations, and environmental fluctuations. The research findings indicate substantial improvements in sensor performance metrics, including response time, sensitivity threshold, and signal-to-noise ratio. Current challenges in manufacturing scalability and cost-effectiveness are addressed, with proposed solutions for large-scale production and seamless system integration. The study outlines promising applications across multiple fields, from advanced prosthetic limbs with enhanced tactile feedback to sophisticated robotic systems capable of precise environmental interaction. Future research directions emphasize the development of more robust and adaptable sensing platforms, focusing on improved durability, reduced power consumption, and enhanced integration capabilities for next-generation biosensing applications.

Organic Photo‐Responsive Piezoelectric Materials Based on Pyrene Molecules for Flexible Sensors

AbstractDue to the advantages of multiplicity, functionality, and flexibility of organic building blocks, organic piezoelectric materials are regarded as next‐generation materials for potential applications in flexible sensors and energy harvesting devices. Here, a new pure organic pyrene‐based molecule, PyPT is presented, which crystallizes in a non‐centrosymmetric structure. PyPT is synthesized and demonstrated to be suitable for developing flexible sensors due to its remarkable piezoelectric properties. The pyrene‐based piezoelectric molecule exhibits excitation wavelength‐dependent emission behavior and aggregation‐caused quenching properties and demonstrated a piezoelectric coefficient (d33) of 8.02 ± 0.26 pm V−1. The output electronic signal of a PyPT‐based flexible sensor shows a significant increase from 30 to 721 pA as the strain increases from 0.12% to 0.59% with a low Young's modulus of 1.63 Gpa. This high‐performance piezoelectric sensor can serve as a sensitive sound sensor for sound detection and recognition based on the basic characteristics of sound, such as amplitude, frequencies, and timbres. This research offers new insights into advancing pure organic luminescent materials with piezoelectric properties, paving the way for applications in flexible electronics for wearables, human–machine interfaces, and the Internet of Things.

Highly sensitive and selective carbon dots sensor for hydrogen sulfide based on dual quenching effect

Highly sensitive and selective carbon dots sensor for hydrogen sulfide based on dual quenching effect

Shape‐Reconfigurable Crack‐Based Strain Sensor with Ultrahigh and Tunable Sensitivity

AbstractIn the field of wearable electronics and human–machine interfaces, there is a growing need for highly sensitive and adaptable sensors capable of detecting a wide range of stimuli with high precision. Traditional sensors often lack the versatility to adjust their sensitivity for different applications. Inspired by the mechanosensory system of spiders, a shape‐reconfigurable crack‐based sensor with ultrahigh and tunable strain sensitivity based on the precise control of nanocrack formation on a shape memory polymer substrate is demonstrated. This design incorporates a line‐patterned substrate composed of a thermoplastic polyurethane (TPU) matrix and thermo‐responsive shape memory polymer, poly(lactic acid) (PLA), to form parallel nanocracks in a thin platinum film. This design achieves an ultrahigh gauge factor of 2.7 × 109 at 2% strain, significantly surpassing conventional sensors. The shape memory property of the TPU/PLA substrate enables tunable strain sensitivity according to the desired strain range, eliminating the need for multiple sensors. The sensor demonstrates exceptional capabilities in detecting subtle strains (as low as 0.025%), monitoring biological signals, and sensing acoustic waves (100–20 000 Hz) with a response time of 0.025 ms. This work represents a significant advancement toward strain sensors with both ultrahigh and tunable sensitivity.

Anti-Tissue-Transglutaminase IgA Antibodies Presence Determination Using Electrochemical Square Wave Voltammetry and Modified Electrodes Based on Polypyrrole and Quantum Dots

A novel electrochemical detection method utilizing a cost-effective hybrid-modified electrode has been established. A glassy carbon (GC) modified electrode was tested for its ability to measure electrochemical tTG antibody levels, which are essential for diagnosing and monitoring Celiac disease (CD). Tissue transglutaminase protein biomolecules are immobilized on a quantum dots-polypyrrole nanocomposite in the improved electrode. Initial, quantum dots (QDs) were obtained from Bombyx mori silk fibroin and embedded in polypyrrole film. Using carbodiimide coupling, a polyamidoamine (PAMAM) dendrimer was linked with GQDs-polypyrrole film to improve sensor sensitivity. The tissue transglutaminase (tTG) antigen was cross-linked onto PAMAM using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC)-N-hydroxy succinimide (NHS) chemistry to develop a nanoprobe that can detect human serum anti-tTG antibodies. The physicochemical characteristics of the synthesized nanocomposite were examined by FTIR, UV-visible, FE-SEM, EDX, and electrochemical studies. The novel electrode measures anti-tissue antibody levels in real time using human blood serum samples. The modified electrode has great repeatability and an 8.7 U/mL detection limit. Serum samples from healthy people and CD patients were compared to standard ELISA kit assays. SPSS and Excel were used for statistical analysis. The improved electrode and detection system can identify anti-tissue antibodies up to 80 U/mL.

Application and Prospects of Nanomaterials in Medical and Environmental Sensing

Driven by the increasing demand for sensing technologies in the field of healthcare and environmental protection, nanomaterials have emerged as critical materials for advancing sensor performance, largely due to their unique physical, chemical, and biological properties that enhance various sensing techniques. This paper examines the application of nanomaterials in medical and environmental sensing, and explores both carbon-based (e.g., graphene, carbon nanotubes) and metal-based nanomaterials, focusing on their contributions to sensor sensitivity, specificity, as well as real-time monitoring. Key applications include early disease detection, blood glucose monitoring, and pollutant detection, particularly for carbon dioxide and nitrates. In addition, the bottom-up and top-down synthesis methods of nanomaterials are compared, highlighting their versatility across various sensing scenarios. Nevertheless, despite the broad application potential of nanomaterials in sensing technology, high production costs, insufficient stability, and processing challenges remain key obstacles. Future research should focus on reducing production costs, enhancing material stability, and minimizing environmental impact to facilitate the practical application of nanomaterials in sensor technology.

Advanced Triboelectric Nanogenerator Sensing Technologies for High‐Efficiency Cardiovascular Monitoring

Triboelectric nanogenerators (TENGs) have emerged as transformative technologies in biosensing, offering unprecedented energy efficiency and precision in monitoring vital physiological signals. This review delves into the cutting‐edge advancements in TENG sensors, highlighting their exceptional potential in bioengineering applications. Key operating mechanisms and advanced materials are explored, with a focus on their impact on sensor sensitivity, durability, and biocompatibility. Cardiovascular monitoring is presented as a pivotal application, where TENG sensors demonstrate exceptional capability in detecting subtle mechanical signals such as pulse waves and heartbeats in real time. Their self‐powered nature eliminates the need for external energy sources, and their inherent scalability and adaptability make them ideal for integration into wearable or implantable devices. Benefits such as miniaturization, energy efficiency, and biocompatibility are discussed, alongside challenges like material fatigue and long‐term stability in biomedical environments. Future directions include optimizing TENG materials for enhanced mechanical robustness and expanding their integration into advanced medical diagnostics. This review provides a comprehensive roadmap for leveraging TENG technologies to revolutionize continuous cardiovascular monitoring and broader medical applications.

Early diagnosis of lung cancer using a sensor gas analysis complex: case report

Background. Currently, low-dose computed tomography (LDCT) is the only screening test that reduces the risk of death from lung cancer. However, there are a number of disadvantages, such as lack of widespread use, high cost, high false-positive rate and the need to conduct studies only in high-risk groups, which significantly limit mass screening. exhaled breath analysis, which uses sensitive breath sensors, is a promising method to improve early diagnosis of lung cancer. Cancer Research Institute of Tomsk National Research Medical Center together with Tomsk State University and Tomsk Polytechnic Research Institute has developed a gas analysis complex capable of analyzing the gas composition of exhaled air with remote sampling from bags. during the study, data obtained by digitizing signals from gas analysis system sensors and patient metadata are recorded in a database for subsequent automated processing and analysis using a neural network. Case description. A 48-year-old female patient with a long history of smoking came to the clinic of the Cancer Research Institute for consultation with suspected pathological infiltration around the celiac trunk detected by abdominal CT. As a clinical trial of the developed gas analytical complex for cancer detection, a sample of exhaled air was taken, and the comparison of the composition of volatile organic compounds (VOCs) with that in the control group (healthy individuals) revealed abnormalities characteristic of lung cancer. the patient underwent a chest CT scan, which revealed stage IIB peripheral cancer of the lower lobe of the left lung. the original sensor gas analysis complex, which has no analogues in Russia, was used for the first time in the detection of lung cancer. the data obtained allowed us to suspect the presence of lung tumor in the patient and perform radical surgical treatment. the composition of VOCs in exhaled air was assessed on day 10 after surgery, and no significant changes in the composition of exhaled air were observed. Conclusion. Machine learning algorithms are actively used to diagnose socially significant diseases. the platforms being developed based on arrays of chemical sensors with data analysis using a neural network are promising candidates for implementation in screening activities.

Fabrication and simulation of silicon nanogaps pH sensor as preliminary study for Retinol Binding Protein 4 (RBP4) detection

In this research, a silicon nanogap biosensor has the potential to play a significant role in the field of biosensors for detecting Retinol Binding Protein 4 (RBP4) molecules due to its unique nanostructure morphology, biocompatibility features, and electrical capabilities. Additionally, as preliminary research for RBP4, a silicon nanogap biosensor with unique molecular gate control for pH measurement was developed. Firstly, using conventional lithography followed by the Reactive-ion etching (RIE) technique, a nanofabrication approach was utilized to produce silicon nanogaps from silicon-on-insulator (SOI) wafers. The critical aspects contributing to the process and size reduction procedures were highlighted to achieve nanometer-scale size. The resulting silicon nanogaps, ranging from 100 nm to 200 nm, were fabricated precisely on the device. Secondly, pH level detection was performed using several types of standard aqueous pH buffer solutions (pH 6, pH 7, pH 12) to test the electrical response of the device. The sensitivity of the silicon nanogap pH sensor was 7.66 pS/pH (R² = 0.97), indicating that the device has a wide range of pH detecting capacity. This also includes the silicon nanogap biosensor validated by simulation, with the sensitivity obtained being 3.24 μA/e.cm² (R² = 0.98). The simulation of the sensitivity is based on the interface charge (Qf) that represents the concentration of RBP4. The results reveal that the silicon nanogap biosensor has excellent characteristics for detecting pH levels and RBP4 with outstanding sensitivity performance. In conclusion, this silicon nanogap biosensor can be used as a new electrical RBP4 biosensor for biomedical diagnostic applications in the future.

Smartphone-assisted hydrogel sensing platform based on double emission carbon dots for portable on-site tetracycline detection.

Innovative double-emission carbon dots (DE-CDs) were synthesized via a one-step hydrothermal method using fennel and m-phenylenediamine (m-PD) as precursors. These DE-CDs exhibited dual emission wavelengths at 432 and 515nm under different excitations, making them highly versatile for fluorescence-based applications. The fluorescence of the DE-CDs was efficiently quenched by tetracycline (TC) through the inner filter effect (IFE), allowing for the construction of a sensitive dual-response fluorescent sensor. This sensor demonstrated a strong exponential correlation with TC concentrations in the range 0.99-118μM, achieving a low detection limit of 53.4nM, which is appropriate for environmental monitoring. To further enhance its practicality, a smartphone-integrated fluorescent hydrogel film sensing platform was developed. This portable and user-friendly system enabled rapid, on-site TC detection in water samples, combining high sensitivity with convenience for real-world applications. The integration of the DE-CD-based sensor into a hydrogel platform addressed the challenge of translating laboratory precision into field-ready tools. This study revealed the potential of DE-CDs as a robust and efficient solution for bridging the gap between laboratory-based analysis and portable, on-site environmental monitoring.

Ultrasensitive Quantification of Neonicotinoid Thiamethoxam in Environment using MOF-derived CuCo2O4/3D rGO Based Electrochemical Sensor Integrated with Optimized Neural Network.

Accurate quantification of neonicotinoid insecticides is pivotal to ensure environmental safety by examining and mitigating their potential harmful effects on pollinators and aquatic ecosystems. In this scenario, detection of neonicotinoid insecticide, thiamethoxam (TMX), is significant for safeguarding ecological balance and human health. Hence, we developed a highly sensitive electrochemical sensor for detection of TMX in environmental samples, utilizing a novel nanocomposite with superior electrocatalytic properties and integrating an optimized neural network for accurate data analysis. The nanocomposite was synthesized via sonochemical approach, combining metal-organic framework (MOF)-derived spinel copper cobaltite (M-CuCo₂O₄) with three-dimensional reduced graphene oxide (3DrGO). Important characterizations were performed on prepared M-CuCo₂O₄/3DrGO composite and was immobilized on a screen-printed carbon electrode (SPCE) for electrochemical investigations. The synergistic effects of M-CuCo₂O₄ and 3DrGO enabled M-CuCo₂O₄/3DrGO/SPCE to achieve exceptional performance towards TMX detection. The sensor exhibited low limit of detection (LOD) of 0.6 nM and wide linear range of 0.15 to 174.52 μM. Furthermore, neural network model demonstrated excellent accuracy in estimating TMX concentrations, achieving a root mean square error (RMSE) of 2.01 and mean absolute error (MAE) of 1.33. The sensor showed remarkable stability and reliability in real samples including agricultural wastewater, red soil, and brown rice, highlighting its practical applicability for TMX monitoring in environmental and agricultural contexts.