High-Performance and Flexible Co-Planar Integrated Microsystem of Carbon-Based All-Solid-State Micro-Supercapacitor and Real-Time Temperature Sensor

With the rapid development of flexible and portable microelectronics,the extreme demand for miniaturized,mechanically flexible,and integrated microsystems are strongly stimulated.Here,biomass-derived carbons(BDCs)are prepared by KOH activation using Qamgur precursor,exhibiting three-dimensional(3D)hierarchical porous structure.Benefiting from unobstructed 3D hierarchical porous structure,BDCs provide an excellent specific capacitance of 433 F g^(-1)and prominent cyclability without capacitance degradation after 50000 cycles at 50 A g^(-1).Furthermore,BDC-based planar micro-supercapacitors(MSCs)without metal collector,prepared by mask-assisted coating,exhibit outstanding areal-specific capacitance of 84 mF cm^(-2)and areal energy density of 10.6μWh cm^(-2),exceeding most of the previous carbon-based MSCs.Impressively,the MSCs disclose extraordinary flexibility with capacitance retention of almost 100%under extreme bending state.More importantly,a flexible planar integrated system composed of the MSC and temperature sensor is assembled to efficiently monitor the temperature variation,providing a feasible route for flexible MSC-based functional micro-devices.

Laser‑Induced and MOF‑Derived Metal Oxide/Carbon Composite for Synergistically Improved Ethanol Sensing at Room temperature

Advancements in sensor technology have significantly enhanced atmospheric monitoring.Notably,metal oxide and carbon(MO_(x)/C)hybrids have gained attention for their exceptional sensitivity and room-temperature sensing performance.However,previous methods of synthesizing MO_(x)/C composites suffer from problems,including inhomogeneity,aggregation,and challenges in micropatterning.Herein,we introduce a refined method that employs a metal–organic framework(MOF)as a precursor combined with direct laser writing.The inherent structure of MOFs ensures a uniform distribution of metal ions and organic linkers,yielding homogeneous MO_(x)/C structures.The laser processing facilitates precise micropatterning(<2μm,comparable to typical photolithography)of the MO_(x)/C crystals.The optimized MOF-derived MO_(x)/C sensor rapidly detected ethanol gas even at room temperature(105 and 18 s for response and recovery,respectively),with a broad range of sensing performance from 170 to 3,400 ppm and a high response value of up to 3,500%.Additionally,this sensor exhibited enhanced stability and thermal resilience compared to previous MOF-based counterparts.This research opens up promising avenues for practical applications in MOF-derived sensing devices.

Novel pressure and displacement sensors based on carbon nanotubes

We report newly designed pressure and displacement capacitive sensors based on a flexible paper–CNT structure.The carbon nanotube（CNT） powder was deposited on a thin paper substrate and was pressed at an elevated temperature.The sheet resistance of the paper–CNT films was in the range of 2–4 kΩ/cm^2. The paper–CNT films were used to fabricate pressure and displacement sensors. The sensitivities of the pressure and the displacement sensors were found to be17.3 p F·m^2/k N and 0.93 10-3p F/μm, respectively. The experimental results were compared with the simulated data and they found good agreement with each other.

Carbon nanotube cuprous oxide composite based pressure sensors

In this paper, we present the design, the fabrication, and the experimental results of carbon nanotube （CNT） and Cu20 composite based pressure sensors. The pressed tablets of the CNT Cu20 composite are fabricated at a pressure of 353 MPa. The diameters of the multiwalled nanotubes （MWNTs） are between 10 nm and 30 nm. The sizes of the Cu20 micro particles are in the range of 3-4 μm. The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm, respectively. In order to make low resistance electric contacts, the two sides of the pressed tablet are covered by silver pastes. The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m^2. The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ±2%.

Study on Response Time of SPE Carbon Monoxide Sensor

The influence of structural design and the parameters of the working electrode on the response time of a solid polymer electrolyte (SPE) carbon monoxide sensor has been studied. Results show that the response time is mainly determined by the RC time constant of the catalyst layer and also related with the working electrode potential.

Analytical Solution of Vibration Analysis on Fixed-Free Single-Walled Carbon Nanotube-Based Mass Sensor

Fixed-free single-walled carbon nanotubes (SWCNTs) have attracted a lot of interest in recent years due to their suitability for a wide range of applications, such as field emission and vacuum microelectronic devices, nanosensors, and nanoactuators. Based on a cantilever beam-bending model with a rigid mass at the free end and mode analysis, an analytical solution is developed in the present study to deal with the resonant frequency and mode shapes of a SWCNT- based mass sensor. The resonant frequency shift and mode shape of the fixed-free SWCNTs caused by the addition of a nanoscale particle to the beam tip are examined in order to explore the suitability of SWCNTs as a mass detector device. The simulation results reveal that the volume of the added particle has little effect on the first resonant frequency. In contrast, the second resonant frequency decreases with increasing the volume of the added particle. Furthermore, the resonant frequency shift of the first mode is very obvious for the amount of added mass, and the second resonant frequency decreases rapidly with increasing volume of added particle. Therefore, the first and second resonant frequencies can be used in the measurement of the mass of added particle and its volume, respectively.

Carbon Nanotube Based Chemical Sensors

Carbon nanotubes CNTs)have been receiving enormous attention in the last decade due to their extraordinary mechanical properties and unique elec- tronic properties.This combination has produced an unprecedented range of applications for CNTs:elec- tronic,logic and memory chips,chemical and biosen- sots,composites,lithium batteries,gas storage,filters and membranes,etc.This presentation will focus on carbon nanotube based sensors and discuss fabrication, testing and performance.

An All‑In‑One Multifunctional Touch Sensor with Carbon‑Based Gradient Resistance Elements

Human–machine interactions using deep-learning methods are important in the research of virtual reality,augmented reality,and metaverse.Such research remains challenging as current interactive sensing interfaces for single-point or multipoint touch input are trapped by massive crossover electrodes,signal crosstalk,propagation delay,and demanding configuration requirements.Here,an all-inone multipoint touch sensor(AIOM touch sensor)with only two electrodes is reported.The AIOM touch sensor is efficiently constructed by gradient resistance elements,which can highly adapt to diverse application-dependent configurations.Combined with deep learning method,the AIOM touch sensor can be utilized to recognize,learn,and memorize human–machine interactions.A biometric verification system is built based on the AIOM touch sensor,which achieves a high identification accuracy of over 98%and offers a promising hybrid cyber security against password leaking.Diversiform human–machine interactions,including freely playing piano music and programmatically controlling a drone,demonstrate the high stability,rapid response time,and excellent spatiotemporally dynamic resolution of the AIOM touch sensor,which will promote significant development of interactive sensing interfaces between fingertips and virtual objects.

Improvement in Sensitivity and Recovery of Single-Walled Carbon Nanotube-Based Gas Sensors

In this paper,an improvement in sensitivity and recovery of the single-walled carbon nanotube (SWNT)-based gas sensors was reported.The sensors were fabricated from SWNT powder by a screen-printing method,followed by annealing for 2 h in open-air at various temperatures.The Raman spectra of the SWNT bundles and the response to ammonia (NH_3) exposure of the sensors indicated that the annealing at a relevant temperature improved the sensor sensitivity.The sensor annealed at 200℃exhibited a high sensitivity in NH_3 detection.After 20 min of exposure to NH_3 at room temperature,the resistance of the sensor increased up to 12% in comparison with its initial value.By evacuating combined with maintaining the flux of carrier gas at 300 sccm,the sensor recovery was significantly speeded.The sensor resistance retrieved to its initial value after only 25 min degassing. These results would be considered in the development of the SWNT-based gas sensors.

Single-Walled Carbon Nanotubes for Flexible Electronics and Sensors

This article reviews the use of electronic quality single-walled carbon nanotubes grown via chemical vapor deposition （CVD） approaches at high temperatures as building blocks for fabricating flexible field-effect devices, such as thin-film transistors （TFTs） and chemical sensors. Dry transfer printing technique is developed for forming films of CVD nanotubes on low-temperature plastic substrates. Examples of TFTs with the use of nanotubes and thin dielectrics and hydrogen sensors with the use of nanotubes decorated with palladium nanoparticles are discussed in detail to demonstrate the promising potentiality of single-walled carbon nanotubes for building high performance flexible devices, which can find applications where traditional devices on rigid substrates are not suitable.

A Study on the Full-Solid-State Electrochemical Systems for Amperometric Carbon Dioxide Gas Sensor Devices

A new type of solid polymer electrolyte based on polyacrylonitrile (PAN )-dimethylsulfoxide (DMSO)-tetrabutylammonium perchlorate (TBAP) system has been prepared. The ionic conductivities of such solid-electrolytes reach values as high as 10-4 S. cm-1 at room temperature. At proper content of each component in the solid-electrolyte the polymeric film has a porous network microstructure of three dimen-sions,and exhibits a good level of mechanical properties and dimensional stability. The full-solid-state elec-trochemical cell contains two coplanar electrodes coated by a thin layer of PAN-DMSO-TBAP solid-elec-trolyte: a Au microdisk as working electrode and a Ag ring counter/reference electrode. This study has shown that the integrated two-electrode assembly can be directly used for the amperometric solid-state car-bon dioxide gas sensor devices,and it shows good response characteristics for direct amperometric determi-nation of the CO2 concentration in the gas phase. Also, such full-solid-state amperometric sensor devices possess their own original advantages.

Sputter Deposited Carbon Material based Fabry-Perot Sensor and Downhole Application

To prevent hydrogen-induced loss and achieve long-term effective parameters monitoring in harsh downhole environment,we proposed a Fabry-Perot sensor with vacuum sputter deposited carbon coating film,in which we employed a deposition technology with a higher particle kinetic energy,closer substrate adhesion,and denser films,to deposit the coating film on the surface of the quartz capillary glass tube to protect the sensor from corrosion.The sensitivity and accuracy of the Fabry-Perot sensor with carbon film deposition can reach 369 nm/MPa and 0.02%FS,respectively.Meanwhile,the sensor has less hysteresis error and good pressure linearity of more than 0.99999 for repeatable pressure measurement.The downhole practice monitoring data indicated that this fiber-optic sensor exhibited excellent performance and the sputter deposited carbon coating can effectively decrease hydrogen loss.

<i>β</i>-cyclodextrin Covalently Functionalized Single-Walled Carbon Nanotubes: Synthesis, Characterization and a Sensitive Biosensor Platform

In this study, we presented the preparation of β-cyclodextrin (β-CD) covalently functionalized single-walled carbon nanotubes (SWCNTs) and its application in modifying the solid glass carbon electrode (GCE). Cyclic voltammetry (CV) method was employed to evaluate the performance of the modified GCE. Solubility experiment indicated the conjugation of SWCNTs and β-CD, SWCNTs-β-CD with 8 wt% β-CD content could be well dispersed in water. High-resolution transmission electron microscopy (HRTEM) demonstrated that the aggregated SWCNTs bundle were effectively exfoliated to small bundle, even individual tube. The β-CD component was grafted on the side walls as well as tips of SWCNTs, and the grafted β-CD component was not uniformly coated on the surface of SWCNTs. The CV measurements indicated the performance of the GCE modified by SWCNTs-β-CD was better than that of the GCE modified by the hybrid of SWCNTs/β-CD, where ascorbic acid (AA) and uric acid (UA) were selected as a prelimiltary substrate to evaluate it. The enhanced performance of the modified GCE should be ascribed to the integration of the excellent electrocatalytic property of SWCNTs with the inclusion ability of β-CD to analyte molecule.

Flexible Strain Sensor Based on 3D Electrospun Carbonized Sponge

Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was studied.Based on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are discussed.After research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is 136.27.In this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real time.Research experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.

Nickel Decorated Single-Wall Carbon Nanotube as CO Sensor

Based on spin-polarized density functional theory (DFT) calculations, the interaction between nickel cluster decorated single-wall carbon nanotube (CNT) and CO molecule has been investigated. DFT calculations are performed with generalized gradient approximation (GGA) using Perdew-Burke-Ernzerhof (PBE) functional. Interaction of CNT and cluster induces spin polarization in the CNT. Nickel decorated CNT has a large magnetic moment of 4.00 μB which decreases to 0.10 μB when CO molecule is absorbed to it. Such a drastic reduction in magnetization may be detected by SQUID magnetometer. Hence by measuring magnetization change, CNT-cluster system may be used as gas detectors. The charge transfer between the systems has been discussed through Mulliken charge analysis for different orientations of the adsorbed CO molecule. We observed that CNT-cluster system acts as electron donor and CO molecule acts as electron acceptor in this study.

Studies on Zeolite Modified Electrode(Ⅰ)─Ascorbic Acid Sensor Based on Carbon Paste Electrode Containing Fe(Ⅲ)Y Zeolite

A new ascorbic acid sensor constituted of carbon paste and Fe(Ⅲ)Y zeolite was studied.The characters of the sensor such as linear range. potential window、apparen Michaelis constant、response time、stability and accuracy wee investigated. The experimental results indicate that the analytical performance of the sensor is satisfactory.

A CuO/TiO_(2)Heterojunction Based CO Sensor with High Response and Selectivity

The use of heterojunctions is a promising solution to the problem of cross-sensitivity in gas sensors.In this work,a carbon monoxide sensor based on the CuO/TiO_(2)heterojunction was designed and fabricated.Due to the good adsorption properties of CuO materials to CO,and the heterojunction interface charge transfer,the CuO/TiO_(2)thin film sensor exhibits high sensitivity to CO at room temperature.The response is as high as 10.8–200 ppm CO,about 10 times its response to H_(2).Interference from H_(2)is greatly reduced by optimizing the structure of the CuO/TiO_(2)heterojunction.This reliable detection of carbon monoxide with excellent discrimination against H_(2)is of great significance for the development of CO gas sensors.

Smoldering charcoal detection in forest soil by multiple CO sensors

Cleaning up residual fires is an important part of forest fire management to avoid the loss of forest resources caused by the recurrence of a residual fire.Existing residual fire detection equipment is mainly infrared temperature detection and smoke identification.Due to the isolation of ground,temperature and smoke characteristics of medium and large smoldering charcoal in some forest soils are not obvious,making it difficult to identify by detection equipment.CO gas is an important detection index for indoor smoldering fire detection,and an important identification feature of hidden smoldering ground fires.However,there is no research on locating smoldering fires through CO detection.We studied the diffusion law of CO gas directly above covered smoldering charcoal as a criterion to design a detection device equipped with multiple CO sensors.According to the motion decomposition search algorithm,the detection device realizes the function of automatically searching for smoldering charcoal.Experimental data shows that the average CO concentration over the covered smoldering charcoal decreases exponentially with increasing height.The size of the search step is related to the reliability of the search algorithm.The detection success corresponding to the small step length is high but the search time is lengthy which can lead to search failure.The introduction of step and rotation factors in search algorithm improves the search efficiency.This study reveals that the average ground CO concentration directly above smoldering charcoal in forests changes with height.Based on this law,a CO gas sensor detection device for hidden smoldering fires has been designed,which enriches the technique of residual fire detection.

Piezoresistive behavior of elastomer composites with segregated network of carbon nanostructures and alumina

Electrically conductive elastomer composites(CECs)with segregated networks of conductive nanofillers show high potential in stretchable strain sensors due to balanced mechanical and electrical properties,yet the sensitivity at low strain is generally insufficient for practical application.Herein,we report an easy and effective way to improve the resistive response to low strain for CECs with segregated network structure via adding stiff alumina into carbon nanostructures(CNS).The CEC containing 0.7 wt%CNS and 5 wt%Al_(2)O_(3) almost sustains the same elasticity(elongation at break of~900%)and conductivity(0.8 S/m)as the control,while the piezoresistive sensitivity is significantly improved.Thermoplastic polyurethane(TPU)composites with a segregated network of hybrid nanofillers(CNS and Al_(2)O_(3))show much higher strain sensitivity(Gauge factor,GF-566)at low strain(45%strain)due to a local stress concentration effect,this sensitivity is superior to that of TPU/CNS composites(GF-11).Such a local stress concentration effect depends on alumina content and its distribution at the TPU particle interface.In addition,CECs with hybrid fillers show better reproducibility in cyclic piezoresistive behavior testing than the control.This work offers an easy method for fabricating CECs with a segregated filler network offering stretchable strain sensors with a high strain sensitivity.

Highly Sensitive Electrochemical Detection of Nitrite Based on Cationic Surfactant Modification of Conductive Carbon Black

Nitrite is a commonly used additive in cured foods and its sensitive detection is important to human health.In this work,a simple but sensitive electrochemical sensor for nitrite was developed.Conductive carbon black(VXC-72R)functionalized with a cationic surfactant cetyltrimethylammonium bromide(CTAB)was used as an electrode material,and was coated on a glassy carbon electrode(GCE)to fabricate the electrochemical sensor(CTAB/VXC-72R/GCE)for nitrite.Zeta potential characterization and a series of electrochemical tests were carried out on several materials.It was found that the present sensor showed an enhanced sensitivity towards nitrite detection due to the enhanced surface positive charge revealed by the Zeta potential.Under optimal conditions,the ranges of good linear relationship between the peak current and the nitrite concentration were obtained to be 0.5-5.0μmol/L and 5.0-1087.0μmol/L with a lower detection limit of 0.30μmol/L.It was also successfully used for the determination of nitrite in cured food samples with excellent reproducibility,stability and selectivity.