Electronic Sensors Research Articles

Textronic Capacitive Sensor with an RFID Interface.

This article presents an innovative combination of textile electrical circuits with advanced capabilities of electronic RFID sensors, indicating the revolutionary nature of the development of textronics, which is used in various areas of life, from fashion to medicine. A review of the literature relating to the construction of textronic RFID identifiers and capacitive textronic sensors is performed. Various approaches to measuring capacity using RFID tags are discussed. This article focuses on presenting the concept of a capacitive sensor with an RFID interface, consisting of a microelectronic part and a textile part. The textile part is based on the WL4007 material, where antennas and capacitive sensors are embroidered using SPARKFUN DEV 11791 conductive thread. The antenna is a half-wave dipole designed to operate at a frequency of 860 MHZ. The microelectronic part is sewn to the textile part and consists of a microcontroller, an RFID-integrated circuit and a coupling loop, placed on the PCB. The embroidered antenna is coupled with a loop on the microelectronic module. This article focuses on presenting various designs of textronic electrodes, enabling various types of measurements. Article presents capacitance measurements of individual sensor electrodes, made using a measuring bridge and a built RFID tag. The sensors' capacity measurement results are shown.

Self-Assembly of Molecular Landers Equipped with Functional Moieties on the Surface: A Mini Review.

The bottom-up fabrication of supramolecular and self-assembly on various substrates has become an extremely relevant goal to achieve prospects in the development of nanodevices for electronic circuitry or sensors. One of the branches of this field is the self-assembly of functional molecular components driven through non-covalent interactions on the surfaces, such as van der Waals (vdW) interactions, hydrogen bonding (HB), electrostatic interactions, etc., allowing the controlled design of nanostructures that can satisfy the requirements of nanoengineering concepts. In this context, non-covalent interactions present opportunities that have been previously explored in several molecular systems adsorbed on surfaces, primarily due to their highly directional nature which facilitates the formation of well-ordered structures. Herein, we review a series of research works by combining STM (scanning tunneling microscopy) with theoretical calculations, to reveal the processes used in the area of self-assembly driven by molecule Landers equipped with functional groups on the metallic surfaces. Combining these processes is necessary for researchers to advance the self-assembly of supramolecular architectures driven by multiple non-covalent interactions on solid surfaces.

Methane (CH4) Detection System Using The TGS2611 Sensor and MQ-4 Sensor

Abstract This research focused on cow dung digesters as measurement samples, utilizing the TGS2611 and MQ-4 sensors, both known for their affordability. The objective was to develop a low-cost gas sensor system for monitoring methane gas concentrations through a straightforward web-based data acquisition platform. The DHT11 sensor was employed to measure air temperature and humidity. The electronic sensor circuit in this research utilized a voltage divider circuit. Testing the performance of the low-cost gas sensor involved integrating it with an anaerobic digestion system. For both the TGS2611 and MQ-4 sensors, the graph illustrating the relationship between sensor voltage (volts) and methane gas concentration (ppm) formed a logarithmic or non-linear pattern. The measurement range for the system was around 4700 ppm to 6300 ppm for TGS2611 and 4000 ppm to 5100 ppm for MQ-4. The sensor sensitivity was determined as 0.5433 Volts/ppm for TGS2611 and 0.5639 Volt/ppm for MQ-4. The TGS2611 sensor exhibited a higher response to changes in methane gas concentration, while the MQ-4 sensor successfully detected methane gas within its designated range. Interestingly, the TGS2611 sensor accurately detected methane gas concentrations above its specified range. The gas sampling procedure involved automatic gas sampling in a vacuum chamber for measurement, a strategy potentially enhancing sensor robustness. This research successfully amalgamated sensor advantages, circuit control, and data analysis to realize an economical yet reliable monitoring system.

The isoniazid drug adsorption on the boron carbide graphene-like monolayer: insights from simulation in the field of medicine

To determine the electrical sensitivity of BC3 nanosheets to isoniazid (IS), DFT simulations were performed. IS molecules were found to have a clear affinity for pure BC3. The adsorption energy of the most stable structure is approximately −22.12 kcal/mol. Reducing the gap between the HOMO and LUMO levels of BC3 nanosheets significantly (from 1.45 to 0.72 V) enhances IS adsorption and consequently improves the electrical conductivity. This finding positions BC3 as a viable choice for applications like IS detection and electronic sensors. Moreover, the adsorption of IS has altered the work function of BC3, suggesting its potential as a function-based sensor capable of detecting IS through significant shifts in field electron emission current levels. BC3 also offers the advantage of rapid IS desorption, with a recovery time of approximately 6.18 ms.

Cellulose nanocomposite tough hydrogels: synergistic self‐healing, adhesive and strain‐sensitive properties

AbstractRecent advancements are notable in electrically conductive hydrogels emulating human skin functions. However, a significant challenge remains: crafting a single conductive gel that integrates self‐healing, robust mechanical strength, and excellent electrical traits. Our innovation lies in a strong, lightweight, curable gel achieved through multiple coordination bonds between cellulose crystals and acid‐treated multi‐walled carbon nanotubes (MWCNTs) in a polymer network. Embedded MWCNTs act as dynamic bridges within a porous structure, giving exceptional mechanical performance. Reversible coordination interactions confer remarkable recovery and reliable mechanical and electrical self‐healing. Additionally, these ionic gels function as adaptable stress sensors, detecting significant movements like finger and joint motions. This work introduces MWCNT‐incorporated nanomaterials with good stretchability, high ion conductivity, remarkable self‐healing nature, and good stress sensitivity. Such proteins hold promise for electronic sensors, wearable devices, and healthcare monitoring, unveiling a path to diverse applications. Our study addresses challenges and unlocks possibilities for materials that can adapt, withstand, and sense in innovative ways. © 2024 Society of Chemical Industry.

Seamless integration of Internet of Things, miniaturization, and environmental chemical surveillance.

IoT is a game-changer across all fields, including chemistry. Embracing sustainable practices and green chemistry, the miniaturization and automation of systems, and their integration into IoT is key to achieving these principles, as a rising trend with momentum. Particularly, IoT and analytical chemistry are linked in the rapid exchange of analytical data for environmental, industrial, healthcare, and educational applications. Meanwhile, cooperation with other fields of science is evident, and there is a prompt and subjective analysis of information related to analytical systems and methodologies. This paper will review the concepts, requirements, and architecture of IoT and its role in the miniaturization and automation of analytical tools using electronic modules and sensors. The aim is to explore the standards and perspectives of IoT and its interaction with different aspects of analytical chemistry. Additionally, it aimed to explain the basics and applications of IoT for chemists, and its relevance to different subfields of analytical chemistry, particularly in the field of environmental chemical surveillance. The article also covers updating IoT devices and creating DIY-based degradation devices to enhance the educational aspect of chemistry and reduce barriers to lab facilities and equipment. Lastly, it will explore how IoT is really important and how it's going to significantly impact analytical chemistry.

Design and validation of dual-point time-differentiated photoplethysmogram (2PPG) wearable for cuffless blood pressure estimation

Background & objectivesMeasurement of blood pressure (BP) in ambulatory patients is crucial for at high-risk cardiovascular patients. A non-obtrusive, non-occluding device that continuously measures BP via photoplethysmography will enable long-term ambulatory assessment of BP. The aim of this study is to validate the metasense 2PPG cuffless wearable design for continuous BP estimation without ECG. MethodsA customized high-speed electronic optical sensor architecture with laterally spaced reflectance pulse oximetry was designed into a simple unobtrusive low-power wearable in the form of a watch. 78 volunteers with a mean age of 32.72 ± 7.4 years (21 to 64), 51% male, 49% female were recruited with ECG-2PPG signals acquired. The fiducial features of the 2PPG morphologies were then attributed to the estimator. A 9–1 K-fold cross-validation was applied in the ML. ResultsThe correlation for PTT-SBP was 0.971 and for PTT-DBP was 0.954. The mean absolute error was 3.167±1.636 mmHg for SBP and 6.4 ± 3.9 mm Hg for DBP. The ambulatory estimate for SBP and DBP for an individual over 3 days with 8-hour recordings was 0.70–0.81 for SBP and 0.42–0.51 for DBP with a ± 2.65 mmHg for SBP and ±2.02 mmHg for DBP. For SBP, 98% of metasense measurements were within 15 mm Hg and for DBP, 91% of metasense measurements were within 10 mmHg ConclusionsThe metasense device provides continuous, non-invasive BP estimations that are comparable to ambulatory BP meters. The portability and unobtrusiveness of this device, as well as the ability to continuously measure BP could one day enable long-term ambulatory BP measurement for precision cardiovascular therapeutic regimens.

A Programmable Ambient Light Sensor with Dark Current Compensation and Wide Dynamic Range.

Ambient light sensors are becoming increasingly popular due to their effectiveness in extending the battery life of portable electronic devices. However, conventional ambient light sensors are large in area and small in dynamic range, and they do not take into account the effects caused due to a dark current. To address the above problems, a programmable ambient light sensor with dark current compensation and a wide dynamic range is proposed in this paper. The proposed ambient light sensor exhibits a low current power consumption of only 7.7 µA in dark environments, and it operates across a wide voltage range (2-5 V) and temperature range (-40-80 °C). It senses ambient light and provides an output current proportional to the ambient light intensity, with built-in dark current compensation to effectively suppress the effects of a dark current. It provides a wide dynamic range over the entire operating temperature range with three selectable output-current gain modes. The proposed ambient light sensor was designed and fabricated using a 0.18 µm standard CMOS process, and the effective area of the chip is 663 µm × 652 µm. The effectiveness of the circuit was verified through testing, making it highly suitable for portable electronic products and fluorescent fiber-optic temperature sensors.

Adsorption, Sensor Properties, AIM Analysis, Docking of an Anticancer Drug Benzamide on Nanocones: SERS, Solvent Effects and DFT Investigation

Using first principles, the electrical response of carbon nanocones (NC) to the drug benzamide (BZE) was investigated using density functional theory (DFT). The adsorption energies of BZE at the nanocone’s bottom (Complex I), side (Complex II), and top (Complex III) are −88.35 kcal/mol, −45.46 kcal/mol and −48.73 kcal/mol. The two other adsorptions, Complexes II and III are physisorption, however, the high value of Eads in the case of Complex I with the drop in bond lengths suggests that Complex I adsorption is chemisorption. The electrical conductivity has risen as a result of the considerable decrease in the nanocone energy gap (from 0.63 eV to 0.61 eV, 0.61 eV and 0.60 eV) caused by the adsorption of BZE. It suggests that the nanocones would be a good fit for the electronic sensors and an appropriate choice for BZE detection. Additionally, the BZE adsorption influences the nanocone’s workfunction, which is reduced by approximately 45.19%, 2.8% and 2.05% for complexes I to III. This suggests that the nanocone could be a workfunction-based sensor for the detection of BZE. The increase in binding affinity in complexes reveals that the nanocones will act as a drug delivery carrier. Theoretically, anticipated Raman spectra of BZE and complexes show SERS activity and inactive normal Raman modes are active in the Raman spectrum of complexes. Compounds II and III exhibit weak noncovalent interactions (NCI) and due to the presence of covalent bonding interaction in compound I, significant changes in other bonding and nonbonding electron densities are observed compared to compounds II and III.

A CMOS-integrated terahertz near-field sensor based on an ultra-strongly coupled meta-atom

Recently, plasmonic-based sensors operating in the terahertz frequency range have emerged as perspective tools for rapid and efficient label-free biosensing applications. In this work, we present a fully electronic approach allowing us to achieve state-of-the-art sensitivity by utilizing a near-field-coupled electronic sensor. We demonstrate that the proposed concept enables the efficient implementation and probing of a so-called ultra-strongly coupled sub-wavelength meta-atom as well as a single resonant circuit, allowing to limit the volume of material under test down to a few picoliter range. The sensor has been monolithically integrated into a cost-efficient silicon-based CMOS technology. Our findings are supported by both numerical and analytical models and validated through experiments. They lay the groundwork for near-future developments, outlining the perspectives for a terahertz microfluidic lab-on-chip dielectric spectroscopy sensor.

FAULT-TOLERANT CONTROL ALGORITHM FOR AUTOMOTIVE ELECTRONIC MECHANICAL BRAKING RAMP ASSIST

The electronic mechanical braking system directly affects the driving safety of automobiles, but there are auxiliary control methods. Therefore, a fault-tolerant control algorithm for automotive electronic mechanical braking ramp assistance is proposed. The faults of the electronic mechanical braking ramp assistance system and select sensor faults are analyzed as the main research object. By introducing a BP neural network, the longitudinal speed of the vehicle, the wheel speed, the difference between the target slip rate and the current slip rate, and the rate of change of the difference are taken as the network input. Online learning is used to adjust and update the weight coefficients of each layer of the network, output fault diagnosis results and optimized PI controller parameters, and achieve fault-tolerant control. Three different types of sensor fault signals were artificially added in the experimental testing. After the proposed fault-tolerant control method, the controlled signals were used to replace the fault signals, ensuring the normal driving of the car.

Boosting the triboelectric performances of biowaste chitosan keratin triboelectric nanogenerator using carbon composite film as charge storage and charge recombination blocking intermediate layer

Environmental conservation efforts are promoting energy-generation technologies that avoid the use of highly polluting fuels and promote the reuse of waste materials. Advances in triboelectric nanogenerators (TENGs) have led to the progress in harvesting energy from ambient mechanical sources and powering small devices and sensors while being compact, flexible, biocompatible, and eco-friendly. Nevertheless, the practical applications of TENG have limitations. Therefore, the development of TENG with excellent triboelectric performance, eco-friendliness, and low cost is crucial. Consequently, an environmentally friendly, inexpensive TENG device with outstanding triboelectric performance was designed using keratin-enhanced chitosan as a tribo-positive material, a carbon film as an intermediate layer, and polytetrafluoroethylene as a triboelectric negative material. The device was purposely designed to simultaneously play a role in waste treatment and efficient green energy harvesting. Therefore, keratin was extracted from recycled fur, and a carbon film was selected to enhance the triboelectric performance because of its excellent electrical conductivity and dielectric constant. The triboelectric properties of a chitosan keratin intermediate layer (CKI)-TENG were systematically investigated. Practical applications of the CKI-TENG in charging electronic devices and waste-noise harvesting were also studied. The developed CKI TENG exhibited outstanding triboelectric performance compared to a TENG device without an intermediate layer. Particularly, the charge transfer, output voltage, and power density was improved by 19%, 46%, and 60%, respectively, compared to the output of the chitosan-keratin (CK) TENG device. It also exhibited outstanding cyclic and charging-discharging stabilities. In addition, the power density of the developed CKI TENG was higher than that of previously reported TENG devices. Thus, it can play a significant role in green and clean energy generation and the utilization of the harvested energy in practical applications, such as biomedical sensors, charging electronic devices, smart textiles, and sensors.

Multifunctional electronic skins for ultra-sensitive strain, temperature, humidity sensing, and energy harvesting

Though gaining increasing attention in various portable and wireless electronic devices and sensors, flexible gels used in strain sensors and triboelectric nanogenerators (TENGs) still suffer from inferior mechanical properties and lack long-term stability. Herein, multifunctional electronic skins (e-skin) from oriented 2D nanosheets enhanced eutectogel were facilely fabricated via a one-step curing strategy with excellent transparency (96%), superb elasticity (1613%), toughness (17.22 MPa). Moreover, the multifunctional e-skin also exhibits temperature and humidity sensibility. Notably, the as-assembled TENG e-skin exhibits high and stable electrical output performances, including an open-circuit voltage of 224 V, short-circuit current of 7.1 μA, and short-circuit charge of 640 nC. Meanwhile, the TENG can easily light up 130 LEDs, charge capacitors to drive a calculator, and sustain a long service life (120 days). Furthermore, it can serve as a self-powered biomechanical sensor to realize the real-time monitoring of various human motions, showing application potentials in wearable electronics, human health management, and energy harvesting systems.

Muscle-inspired MXene-based conductive hydrogel by magnetic induced for flexible multifunctional sensors

In recent years, conductive hydrogel-based flexible electronic sensor devices have gained widespread attention in the fields of flexible wearable devices, human-machine interaction interfaces, medical monitoring, etc. However, conventional conductive hydrogels struggle to concurrently achieve exceptional mechanical properties and high conductivity, often exhibiting isotropic mechanical performance and sensing characteristics. In contrast, biological tissues typically demonstrate anisotropic mechanical properties and sensing capabilities due to their ordered microstructure. Drawing inspiration from the ordered structures of biological tissues, this study proposed a simple strategy to fabricate high-strength anisotropic MXene-based conductive hydrogels. Initially, a magnetic and conductive two-dimensional nanohybrid material (PDA-Fe3O4-MXene) was synthesized via acid etching and PDA-mediated co-precipitation methods. Secondly, a magnetic field-induced orientation strategy was employed to induce the oriented arrangement of PDA-Fe3O4-MXene within a dual-network polyvinyl alcohol/polyacrylamide (PAAm/PVA) hydrogel. Subsequently, the oriented PDA-Fe3O4-MXene structure was fixed in the dual-network hydrogel by the photopolymerization and freezing-thawing methods. The anisotropic conductive hydrogel exhibited a highly oriented structure, conferring its anisotropic mechanical properties and conductivity. Its mechanical and conductive performances were enhanced in an anisotropic manner, demonstrating outstanding tensile strength (156 KPa) and good conductivity (1.10 mS/cm). Moreover, the conductive hydrogel-based sensors showcased a broad working range (3 %–300 %), rapid response time (290 ms), high sensitivity, and exceptional stability. This work presents a novel approach for constructing flexible electronic devices based on anisotropic hydrogels, offering promising prospects for various applications.

Polyurethane-Encapsulated Biomass Films Based on MXene@Loofah Sponge for Piezoresistive Pressure Sensor Applications.

Multifunctional wearable electronic sensors exhibit significant potential for applications in health management, motion tracking, intelligent healthcare, etc. In this study, we developed a novel assembly method for a polymeric silver nanowire (Ag NW)/transition metal carbide/nitride (MXene) @Loofah device using a facile solution dip-coating technique. During the pretreatment phase, the loofah was conditioned with polydiallyldimethylammonium chloride (PDAC), promoting the self-assembly of MXene layers and bolstering device stability. Then, the Ag NWs/MXene@Loofah was packaged with polyurethane to form a piezoresistive pressure sensor, which demonstrated superior pressure-sensing capabilities and was adept at registering movements of human joints and even subtle pulses. The design strategy presents a novel and rational approach to developing efficient pressure sensors.

Nano-carbon/PIL modified cellulose wearable sensors by computer aided patterning

The conductive modification of cellulose substrates can be achieved through the attachment of nanocarbons (NCs), enabling the production of a wide range of wearable eco-friendly sensors. However, the economical fabrication of durable wearable devices on cellulose, without disrupting the conjugated structure of NCs, poses an enduring challenge. In this work, we report a stable dispersion system of NCs by using an imidazole type poly (ionic liquid) (PIL-Cl). Various kinds of cellulose substrates only require simple immersion in the dispersion liquid to attain conductivity. The paper and cotton fabric conductors fabricated in this manner exhibited exceptional flexibility, bendability, and electrical stability. We designed joint motion detectors with a large strain range (GF = 1.3) by origami, in which the electrical performance remained stable after undergoing 5000 cycles of maximum deformation (−50 %–150 %). Additionally, by utilizing computer aided technology, NCs-(PIL-Cl) system can create conductive patterns in any form. Based on this, we have manufactured a range of wearable electronic sensors, including masks for monitoring respiration, touch-sensitive circuits and information transmission devices on cotton clothing. This system provides a low-cost option for the fabrication of cellulose wearable sensors, suitable for large-scale production and applications.

Intrinsically stretchable phototransistors with polymer-QD-polymer multi-layered hybrid films for visible-NIR perspective electronic skin sensors

Stretchable phototransistors represent a crucial component in the development of skin-inspired optoelectronics. Although there have been significant advancements in the development of skin-like photosensitive semiconductors, technology for stretchable phototransistors that can detect a broad spectrum of wavelengths from near-infrared (NIR) to visible light is still in its early stages. This study introduces an intrinsically stretchable phototransistor employing hybrid semiconductor films consisting of polymer semiconductors (PSC) and quantum dots (QDs). The hybrid multi-layered semiconductor film (PSC/QDs/PSC) possesses wide-ranging color sensitivity from NIR to visible light, along with high photosensitivity and photoresponsivity. Furthermore, our phototransistor exhibits remarkable strain-insensitive, photo-response characteristics, maintaining performance even under 50% strain and enduring 10,000 strain cycles. Notably, the phototransistor array, featuring a distinctive dodecagon shape of source/drain electrodes, effectively responds to NIR and visible light stimuli, even when subjected to substantial areal strains of up to 38%.

A super-hydrophilic graphite directly from lignin enabled by a room-temperature cascade catalytic carbonization

A cost-effective, and low-energy room-temperature cascade catalytic carbonization strategy is demonstrated for converting lignin into graphite with a high yield of 87 %, a high surface potential of −37 eV and super-hydrophilicity. This super-hydrophilic feature endows the lignin-derived graphite to be dispersed in a variety of polar solvents, which is important for its future applications. Encapsulating of liquid metals with the graphite for electrical circuit patterning on flexible substrates is also advocated. These written patterns show superb conductivity of 4.9 × 106 S/m, offering good performance stability and reliability while being repeatedly stretched, folded, twisted, and bent. This will offer new designs for flexible electronic devices, sensors, and biomedical devices.

High temperature co-polyester thermoplastic elastomer nanocomposites for flexible self-regulating heating devices

Pyroresistive polymer composites are smart materials with great promise in numerous fields of electronic devices, including temperature and strain sensors, self-regulating heating, and over-current/over-temperature protective devices. However, the operational window of these materials is limited by the phase transition temperatures of the polymer matrix and the brittleness of the composites. Herein, a conductive polymer composite based on a co-polyester thermoplastic elastomer reinforced with graphene nanoplatelets (GNPs) was developed, which exhibits a positive temperature coefficient (PTC) switching temperature of 200 °C. This system shows a more gradual increase in resistivity with temperature and a less pronounced drop in resistivity past the critical transition temperature than other PTC composites. Moreover, Joule heating experiments revealed the ability to regulate at a predefined maximum temperature (within 150 – 200 °C), tuneable through parameters such as filler concentration, applied voltage and thermal boundary conditions, as also demonstrated by multiphysics simulations. Due to the more gradual PTC curve, this composite can produce steady state heating far below the PTC peak, unlike almost all other PTC materials: a unique advantage for self-regulating heating devices as the polymer is not in a melt state, reducing polymer degradation, filler mobility and increasing safety margin before onset of NTC behaviour.

Exfoliation of Graphite into Graphene Oxide and Reduction by Plant Extract to Synthesize Graphene

Graphene oxide (GO) is a demand material in industrial field for many applications such as electronic devices, capacitor and sensor. This is due to its unique structures and excellent properties. The GO sheets were exfoliated from graphite rod in electrochemical exfoliation. To reduce GO, an electrochemical reduction of GO using green tea was carried out in this research. The conventional chemical reduction method consumed highly toxic and strongly hazardous chemicals such as hydrazine to reduce GO to reduced GO (RGO). Therefore, a green synthesis method was proposed by using green tea leaves extract as the reducing agent to synthesize RGO. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) results show that low amount of oxygen-containing functional groups was remained after green tea reduction due to weak reduction capability by green tea. In addition, EDX indicates that oxygen content of GO was decreased from 23.23 to 16.89 Mass% after green tea reduction.